diff --git a/applications/solvers/basic/potentialFoam/createFields.H b/applications/solvers/basic/potentialFoam/createFields.H
index 89460e2037..352458d00c 100644
--- a/applications/solvers/basic/potentialFoam/createFields.H
+++ b/applications/solvers/basic/potentialFoam/createFields.H
@@ -40,7 +40,7 @@ if (args.found("initialiseUBCs"))
 // converting fixed-value BCs to zero-gradient and vice versa.
 
 // Allow override from command-line -pName option
-const word pName = args.get<word>("pName", "p");
+const word pName = args.getOrDefault<word>("pName", "p");
 
 // Infer the pressure BCs from the velocity
 wordList pBCTypes
diff --git a/applications/solvers/basic/potentialFoam/overPotentialFoam/createFields.H b/applications/solvers/basic/potentialFoam/overPotentialFoam/createFields.H
index 1f4f06550c..c793af226d 100644
--- a/applications/solvers/basic/potentialFoam/overPotentialFoam/createFields.H
+++ b/applications/solvers/basic/potentialFoam/overPotentialFoam/createFields.H
@@ -40,7 +40,7 @@ if (args.found("initialiseUBCs"))
 // converting fixed-value BCs to zero-gradient and vice versa.
 
 // Allow override from command-line -pName option
-const word pName = args.get<word>("pName", "p");
+const word pName = args.getOrDefault<word>("pName", "p");
 
 // Infer the pressure BCs from the velocity
 wordList pBCTypes
diff --git a/applications/solvers/lagrangian/DPMFoam/createFields.H b/applications/solvers/lagrangian/DPMFoam/createFields.H
index aa78161d58..97e8e21b41 100644
--- a/applications/solvers/lagrangian/DPMFoam/createFields.H
+++ b/applications/solvers/lagrangian/DPMFoam/createFields.H
@@ -121,7 +121,7 @@ volScalarField alphac
 
 const word kinematicCloudName
 (
-    args.get<word>("cloud", "kinematicCloud")
+    args.getOrDefault<word>("cloud", "kinematicCloud")
 );
 
 Info<< "Constructing kinematicCloud " << kinematicCloudName << endl;
diff --git a/applications/solvers/lagrangian/icoUncoupledKinematicParcelFoam/createFields.H b/applications/solvers/lagrangian/icoUncoupledKinematicParcelFoam/createFields.H
index 3191bbf7a7..b39ce87325 100644
--- a/applications/solvers/lagrangian/icoUncoupledKinematicParcelFoam/createFields.H
+++ b/applications/solvers/lagrangian/icoUncoupledKinematicParcelFoam/createFields.H
@@ -59,7 +59,7 @@ volScalarField mu
 
 const word kinematicCloudName
 (
-    args.get<word>("cloud", "kinematicCloud")
+    args.getOrDefault<word>("cloud", "kinematicCloud")
 );
 
 Info<< "Constructing kinematicCloud " << kinematicCloudName << endl;
diff --git a/applications/solvers/lagrangian/uncoupledKinematicParcelFoam/createFields.H b/applications/solvers/lagrangian/uncoupledKinematicParcelFoam/createFields.H
index bf12d76bd8..33921cc6ce 100644
--- a/applications/solvers/lagrangian/uncoupledKinematicParcelFoam/createFields.H
+++ b/applications/solvers/lagrangian/uncoupledKinematicParcelFoam/createFields.H
@@ -51,7 +51,7 @@ autoPtr<compressible::turbulenceModel> turbulence
 
 const word kinematicCloudName
 (
-    args.get<word>("cloud", "kinematicCloud")
+    args.getOrDefault<word>("cloud", "kinematicCloud")
 );
 
 Info<< "Constructing kinematicCloud " << kinematicCloudName << endl;
diff --git a/applications/test/argList/Test-argList.C b/applications/test/argList/Test-argList.C
index 2ec91ec05c..4ecc8859f5 100644
--- a/applications/test/argList/Test-argList.C
+++ b/applications/test/argList/Test-argList.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2017-2019 OpenCFD Ltd.
+    Copyright (C) 2017-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -29,11 +29,53 @@ Description
 
 #include "argList.H"
 #include "IOstreams.H"
+#include "MinMax.H"
 #include "Switch.H"
 #include "StringStream.H"
 
 using namespace Foam;
 
+
+void predicateTests_label(const word& optName, const argList& args)
+{
+    Info<< "predicate tests for " << optName << nl;
+
+    const bool throwingError = FatalError.throwExceptions();
+    try
+    {
+        label val;
+        val = args.getCheck<label>(optName, labelMinMax::ge(0));
+    }
+    catch (const Foam::error& err)
+    {
+        Info<< "Caught FatalError "
+            << err << nl << endl;
+    }
+
+    FatalError.throwExceptions(throwingError);
+}
+
+
+void predicateTests_scalar(const word& optName, const argList& args)
+{
+    Info<< "predicate tests for " << optName << nl;
+
+    const bool throwingError = FatalError.throwExceptions();
+    try
+    {
+        scalar val;
+        val = args.getCheck<scalar>(optName, scalarMinMax::ge(0));
+    }
+    catch (const Foam::error& err)
+    {
+        Info<< "Caught FatalError "
+            << err << nl << endl;
+    }
+
+    FatalError.throwExceptions(throwingError);
+}
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 // Main program:
 
@@ -47,6 +89,11 @@ int main(int argc, char *argv[])
     argList::addOption("scalar", "value", "Test parsing of scalar");
     argList::addOption("string", "value", "Test string lookup");
     argList::addOption("relative", "PATH", "Test relativePath");
+    argList::addBoolOption
+    (
+        "predicates",
+        "Apply some predicate tests (for label and scalar)"
+    );
 
     // These are actually lies (never had -parseLabel, -parseScalar etc),
     // but good for testing...
@@ -105,6 +152,11 @@ int main(int argc, char *argv[])
     if (args.readIfPresent("label", ival))
     {
         Info<< ival << nl;
+
+        if (args.found("predicates"))
+        {
+            predicateTests_label("label", args);
+        }
     }
     else
     {
@@ -115,6 +167,11 @@ int main(int argc, char *argv[])
     if (args.readIfPresent("scalar", sval))
     {
         Info<< sval << nl;
+
+        if (args.found("predicates"))
+        {
+            predicateTests_scalar("scalar", args);
+        }
     }
     else
     {
diff --git a/applications/test/checkDecomposePar/Test-checkDecomposePar.C b/applications/test/checkDecomposePar/Test-checkDecomposePar.C
index 99ea6a2435..d664615503 100644
--- a/applications/test/checkDecomposePar/Test-checkDecomposePar.C
+++ b/applications/test/checkDecomposePar/Test-checkDecomposePar.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2017 OpenCFD Ltd.
+    Copyright (C) 2017-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -86,7 +86,8 @@ int main(int argc, char *argv[])
     instantList times = timeSelector::selectIfPresent(runTime, args);
 
     // Allow override of decomposeParDict location
-    const fileName decompDictFile = args.get<fileName>("decomposeParDict", "");
+    const fileName decompDictFile =
+        args.getOrDefault<fileName>("decomposeParDict", "");
 
     wordList regionNames;
     wordList regionDirs;
diff --git a/applications/test/decomposePar/Test-decomposePar.C b/applications/test/decomposePar/Test-decomposePar.C
index 3a719f375a..e21dec2807 100644
--- a/applications/test/decomposePar/Test-decomposePar.C
+++ b/applications/test/decomposePar/Test-decomposePar.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2017-2018 OpenCFD Ltd.
+    Copyright (C) 2017-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -100,8 +100,8 @@ int main(int argc, char *argv[])
     const bool allRegions = args.found("allRegions");
     const bool verbose    = args.found("verbose");
 
-    const label numSubdomains = args.get<label>("domains", 0);
-    const word methodName = args.get<word>("method", word::null);
+    const label numSubdomains = args.getOrDefault<label>("domains", 0);
+    const word methodName = args.getOrDefault<word>("method", word::null);
 
     // Set time from database
     #include "createTime.H"
@@ -109,7 +109,8 @@ int main(int argc, char *argv[])
     instantList times = timeSelector::selectIfPresent(runTime, args);
 
     // Allow override of decomposeParDict location
-    const fileName decompDictFile = args.get<fileName>("decomposeParDict", "");
+    const fileName decompDictFile =
+        args.getOrDefault<fileName>("decomposeParDict", "");
 
     // Get all region names
     wordList regionNames;
@@ -123,7 +124,8 @@ int main(int argc, char *argv[])
     else
     {
         regionNames.resize(1);
-        regionNames.first() = args.get<word>("region", fvMesh::defaultRegion);
+        regionNames.first() =
+            args.getOrDefault<word>("region", fvMesh::defaultRegion);
     }
 
     forAll(regionNames, regioni)
diff --git a/applications/test/externalFileCoupler/Test-externalFileCoupler.C b/applications/test/externalFileCoupler/Test-externalFileCoupler.C
index 7a7b8007c2..c90e766aac 100644
--- a/applications/test/externalFileCoupler/Test-externalFileCoupler.C
+++ b/applications/test/externalFileCoupler/Test-externalFileCoupler.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2017 OpenCFD Ltd.
+    Copyright (C) 2017-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -47,7 +47,7 @@ int main(int argc, char *argv[])
 
     #include "setRootCase.H"
 
-    const label maxCount = args.get<label>("max", 1000);
+    const label maxCount = args.getOrDefault<label>("max", 1000);
 
     externalFileCoupler coupler;
 
diff --git a/applications/test/momentOfInertia/Test-momentOfInertia.C b/applications/test/momentOfInertia/Test-momentOfInertia.C
index 87111b3541..6af16dbec9 100644
--- a/applications/test/momentOfInertia/Test-momentOfInertia.C
+++ b/applications/test/momentOfInertia/Test-momentOfInertia.C
@@ -6,6 +6,7 @@
     \\/      M anipulation   |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -198,7 +199,7 @@ int main(int argc, char *argv[])
     }
 
     {
-        const label celli = args.get<label>("cell", 0);
+        const label celli = args.getOrDefault<label>("cell", 0);
 
         tensorField mI(momentOfInertia::meshInertia(mesh));
 
diff --git a/applications/test/spline/Test-spline.C b/applications/test/spline/Test-spline.C
index 869eb844b7..4d9af262dc 100644
--- a/applications/test/spline/Test-spline.C
+++ b/applications/test/spline/Test-spline.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2013 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -67,7 +68,7 @@ int main(int argc, char *argv[])
 
     bool useBSpline = args.found("B");
     bool useCatmullRom = args.found("CMR");
-    const label nSeg = args.get<label>("n", 20);
+    const label nSeg = args.getOrDefault<label>("n", 20);
 
     if (!useCatmullRom && !useBSpline)
     {
diff --git a/applications/test/surfaceIntersection/Test-surfaceIntersection.C b/applications/test/surfaceIntersection/Test-surfaceIntersection.C
index bd3ba4487a..e2749e08a9 100644
--- a/applications/test/surfaceIntersection/Test-surfaceIntersection.C
+++ b/applications/test/surfaceIntersection/Test-surfaceIntersection.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2017 OpenCFD Ltd.
+    Copyright (C) 2017-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -130,7 +130,7 @@ int main(int argc, char *argv[])
     #include "setRootCase.H"
     #include "createTime.H"
 
-    const scalar scaleFactor = args.get<scalar>("scale", -1);
+    const scalar scaleFactor = args.getOrDefault<scalar>("scale", -1);
 
     const word outputFile(args.executable() + ".obj");
 
diff --git a/applications/test/surfaceMeshConvert/Test-surfaceMeshConvert.C b/applications/test/surfaceMeshConvert/Test-surfaceMeshConvert.C
index 4f2b14b7db..dd02351710 100644
--- a/applications/test/surfaceMeshConvert/Test-surfaceMeshConvert.C
+++ b/applications/test/surfaceMeshConvert/Test-surfaceMeshConvert.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2016 OpenCFD Ltd.
+    Copyright (C) 2016-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -141,7 +141,7 @@ int main(int argc, char *argv[])
     #include "setRootCase.H"
 
     const bool     optStdout = args.found("stdout");
-    const scalar scaleFactor = args.get<scalar>("scale", 0);
+    const scalar scaleFactor = args.getOrDefault<scalar>("scale", 0);
 
     const fileName importName = args[1];
     const fileName exportName = optStdout ? "-stdout" : args[2];
diff --git a/applications/test/surfaceWriter/Test-surfaceWriter.C b/applications/test/surfaceWriter/Test-surfaceWriter.C
index 4b2384c31f..c1826f2fe1 100644
--- a/applications/test/surfaceWriter/Test-surfaceWriter.C
+++ b/applications/test/surfaceWriter/Test-surfaceWriter.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019 OpenCFD Ltd.
+    Copyright (C) 2019-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -84,8 +84,7 @@ int main(int argc, char *argv[])
         return 1;
     }
 
-    const word writerType =
-        args.lookupOrDefault<word>("type", exportName.ext());
+    const word writerType = args.getOrDefault<word>("type", exportName.ext());
 
     auto surfWriter = surfaceWriter::New(writerType);
 
diff --git a/applications/test/tokenize/Test-tokenize.C b/applications/test/tokenize/Test-tokenize.C
index b62adf796e..d3c6eb1637 100644
--- a/applications/test/tokenize/Test-tokenize.C
+++ b/applications/test/tokenize/Test-tokenize.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -53,7 +54,7 @@ int main(int argc, char *argv[])
 
     argList args(argc, argv, false, true);
 
-    const label repeat = args.get<label>("repeat", 1);
+    const label repeat = args.getOrDefault<label>("repeat", 1);
 
     const bool optVerbose = args.found("verbose");
 
diff --git a/applications/test/vtkSeriesWriter/Test-vtkSeriesWriter.C b/applications/test/vtkSeriesWriter/Test-vtkSeriesWriter.C
index 7724cebea0..1cc4ad3026 100644
--- a/applications/test/vtkSeriesWriter/Test-vtkSeriesWriter.C
+++ b/applications/test/vtkSeriesWriter/Test-vtkSeriesWriter.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2018 OpenCFD Ltd.
+    Copyright (C) 2018-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -47,7 +47,7 @@ int main(int argc, char *argv[])
 
     argList args(argc, argv, false, true);
 
-    const scalar currTime = args.get<scalar>("time", GREAT);
+    const scalar currTime = args.getOrDefault<scalar>("time", GREAT);
 
     Info<< "Using currTime = " << currTime << nl
         << "when loading " << (args.size()-1) << " files" << nl << nl;
diff --git a/applications/tools/foamCalc/foamCalc.C b/applications/tools/foamCalc/foamCalc.C
index f16886188f..d96df259de 100644
--- a/applications/tools/foamCalc/foamCalc.C
+++ b/applications/tools/foamCalc/foamCalc.C
@@ -125,7 +125,7 @@ int main(int argc, char *argv[])
     }
 
     {
-        const int prec = args.lookupOrDefault<int>("precision", 0u);
+        const int prec = args.getOrDefault<int>("precision", 0u);
         if (prec > 0)
         {
             IOstream::defaultPrecision(prec);
diff --git a/applications/utilities/mesh/advanced/combinePatchFaces/combinePatchFaces.C b/applications/utilities/mesh/advanced/combinePatchFaces/combinePatchFaces.C
index e54c3325c9..a37ac14a39 100644
--- a/applications/utilities/mesh/advanced/combinePatchFaces/combinePatchFaces.C
+++ b/applications/utilities/mesh/advanced/combinePatchFaces/combinePatchFaces.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2015 OpenFOAM Foundation
-    Copyright (C) 2016-2018 OpenCFD Ltd.
+    Copyright (C) 2016-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -383,7 +383,7 @@ int main(int argc, char *argv[])
 
     // Sin of angle between two consecutive edges on a face.
     // If sin(angle) larger than this the face will be considered concave.
-    const scalar concaveAngle = args.get<scalar>("concaveAngle", 30);
+    const scalar concaveAngle = args.getOrDefault<scalar>("concaveAngle", 30);
 
     const scalar concaveSin = Foam::sin(degToRad(concaveAngle));
 
diff --git a/applications/utilities/mesh/advanced/splitCells/splitCells.C b/applications/utilities/mesh/advanced/splitCells/splitCells.C
index 417819c142..916f744d21 100644
--- a/applications/utilities/mesh/advanced/splitCells/splitCells.C
+++ b/applications/utilities/mesh/advanced/splitCells/splitCells.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -561,7 +562,7 @@ int main(int argc, char *argv[])
     const bool geometry  = args.found("geometry");
     const bool overwrite = args.found("overwrite");
 
-    const scalar edgeTol = args.get<scalar>("tol", 0.2);
+    const scalar edgeTol = args.getOrDefault<scalar>("tol", 0.2);
 
     Info<< "Trying to split cells with internal angles > feature angle\n" << nl
         << "featureAngle      : " << featureAngle << nl
diff --git a/applications/utilities/mesh/conversion/ansysToFoam/ansysToFoam.L b/applications/utilities/mesh/conversion/ansysToFoam/ansysToFoam.L
index 33e06e70a8..cafcdf67ad 100644
--- a/applications/utilities/mesh/conversion/ansysToFoam/ansysToFoam.L
+++ b/applications/utilities/mesh/conversion/ansysToFoam/ansysToFoam.L
@@ -323,7 +323,7 @@ int main(int argc, char *argv[])
         FatalError.exit();
     }
 
-    const scalar scaleFactor = args.get<scalar>("scale", 1);
+    const scalar scaleFactor = args.getOrDefault<scalar>("scale", 1);
 
     #include "createTime.H"
 
diff --git a/applications/utilities/mesh/conversion/ccm/ccmToFoam/ccmToFoam.C b/applications/utilities/mesh/conversion/ccm/ccmToFoam/ccmToFoam.C
index 6fda2d0150..14855f0931 100644
--- a/applications/utilities/mesh/conversion/ccm/ccmToFoam/ccmToFoam.C
+++ b/applications/utilities/mesh/conversion/ccm/ccmToFoam/ccmToFoam.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016 OpenCFD Ltd.
+    Copyright (C) 2016-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -188,7 +188,7 @@ int main(int argc, char *argv[])
     }
 
     // By default, no scaling
-    const scalar scaleFactor = args.get<scalar>("scale", 1);
+    const scalar scaleFactor = args.getOrDefault<scalar>("scale", 1);
 
     // Default to binary output, unless otherwise specified
     const IOstream::streamFormat format =
diff --git a/applications/utilities/mesh/conversion/cfx4ToFoam/cfx4ToFoam.C b/applications/utilities/mesh/conversion/cfx4ToFoam/cfx4ToFoam.C
index ea89273200..903767ab43 100644
--- a/applications/utilities/mesh/conversion/cfx4ToFoam/cfx4ToFoam.C
+++ b/applications/utilities/mesh/conversion/cfx4ToFoam/cfx4ToFoam.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -71,7 +72,7 @@ int main(int argc, char *argv[])
          FatalError.exit();
     }
 
-    const scalar scaleFactor = args.get<scalar>("scale", 1);
+    const scalar scaleFactor = args.getOrDefault<scalar>("scale", 1);
 
     #include "createTime.H"
 
diff --git a/applications/utilities/mesh/conversion/fireToFoam/fireToFoam.C b/applications/utilities/mesh/conversion/fireToFoam/fireToFoam.C
index 952141faab..021907f096 100644
--- a/applications/utilities/mesh/conversion/fireToFoam/fireToFoam.C
+++ b/applications/utilities/mesh/conversion/fireToFoam/fireToFoam.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016 OpenCFD Ltd.
+    Copyright (C) 2016-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -105,7 +105,7 @@ int main(int argc, char *argv[])
     (
         args[1],
         // Default no scaling
-        args.get<scalar>("scale", 1)
+        args.getOrDefault<scalar>("scale", 1)
     );
 
 
diff --git a/applications/utilities/mesh/conversion/fluentMeshToFoam/fluentMeshToFoam.L b/applications/utilities/mesh/conversion/fluentMeshToFoam/fluentMeshToFoam.L
index 877b844c66..8623da54ec 100644
--- a/applications/utilities/mesh/conversion/fluentMeshToFoam/fluentMeshToFoam.L
+++ b/applications/utilities/mesh/conversion/fluentMeshToFoam/fluentMeshToFoam.L
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -904,7 +905,7 @@ int main(int argc, char *argv[])
         FatalError.exit();
     }
 
-    const scalar scaleFactor = args.get<scalar>("scale", 1);
+    const scalar scaleFactor = args.getOrDefault<scalar>("scale", 1);
 
     const bool writeSets  = args.found("writeSets");
     const bool writeZones = args.found("writeZones");
diff --git a/applications/utilities/mesh/conversion/foamToStarMesh/foamToStarMesh.C b/applications/utilities/mesh/conversion/foamToStarMesh/foamToStarMesh.C
index c37c7dcf8c..e34ddaa85d 100644
--- a/applications/utilities/mesh/conversion/foamToStarMesh/foamToStarMesh.C
+++ b/applications/utilities/mesh/conversion/foamToStarMesh/foamToStarMesh.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2016 OpenCFD Ltd.
+    Copyright (C) 2016-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -99,7 +99,7 @@ int main(int argc, char *argv[])
     }
 
     // Default rescale from [m] to [mm]
-    const scalar scaleFactor = args.get<scalar>("scale", 1000);
+    const scalar scaleFactor = args.getOrDefault<scalar>("scale", 1000);
     const bool  writeBndFile = !args.found("noBnd");
 
     #include "createPolyMesh.H"
diff --git a/applications/utilities/mesh/conversion/foamToSurface/foamToSurface.C b/applications/utilities/mesh/conversion/foamToSurface/foamToSurface.C
index 4d684cdb74..17703601d8 100644
--- a/applications/utilities/mesh/conversion/foamToSurface/foamToSurface.C
+++ b/applications/utilities/mesh/conversion/foamToSurface/foamToSurface.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -83,7 +84,7 @@ int main(int argc, char *argv[])
 
     fileName exportName = args[1];
 
-    const scalar scaleFactor = args.get<scalar>("scale", 0);
+    const scalar scaleFactor = args.getOrDefault<scalar>("scale", 0);
     const bool doTriangulate = args.found("tri");
 
     fileName exportBase = exportName.lessExt();
diff --git a/applications/utilities/mesh/conversion/gambitToFoam/gambitToFoam.L b/applications/utilities/mesh/conversion/gambitToFoam/gambitToFoam.L
index bb213665cf..cbd4172c75 100644
--- a/applications/utilities/mesh/conversion/gambitToFoam/gambitToFoam.L
+++ b/applications/utilities/mesh/conversion/gambitToFoam/gambitToFoam.L
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -648,7 +649,7 @@ int main(int argc, char *argv[])
          FatalError.exit();
     }
 
-    const scalar scaleFactor = args.get<scalar>("scale", 1);
+    const scalar scaleFactor = args.getOrDefault<scalar>("scale", 1);
 
     #include "createTime.H"
 
diff --git a/applications/utilities/mesh/conversion/kivaToFoam/kivaToFoam.C b/applications/utilities/mesh/conversion/kivaToFoam/kivaToFoam.C
index 464029faee..e9dd7b91fd 100644
--- a/applications/utilities/mesh/conversion/kivaToFoam/kivaToFoam.C
+++ b/applications/utilities/mesh/conversion/kivaToFoam/kivaToFoam.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2015 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -87,7 +88,8 @@ int main(int argc, char *argv[])
     #include "setRootCase.H"
     #include "createTime.H"
 
-    const fileName kivaFileName = args.get<fileName>("file", "otape17");
+    const fileName kivaFileName =
+        args.getOrDefault<fileName>("file", "otape17");
 
     kivaVersions kivaVersion = kiva3v;
     if (args.found("version"))
@@ -113,7 +115,7 @@ int main(int argc, char *argv[])
         }
     }
 
-    const scalar zHeadMin = args.get<scalar>("zHeadMin", -GREAT);
+    const scalar zHeadMin = args.getOrDefault<scalar>("zHeadMin", -GREAT);
 
     #include "readKivaGrid.H"
 
diff --git a/applications/utilities/mesh/conversion/plot3dToFoam/plot3dToFoam.C b/applications/utilities/mesh/conversion/plot3dToFoam/plot3dToFoam.C
index c657922211..78e8381bb6 100644
--- a/applications/utilities/mesh/conversion/plot3dToFoam/plot3dToFoam.C
+++ b/applications/utilities/mesh/conversion/plot3dToFoam/plot3dToFoam.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -96,7 +97,7 @@ int main(int argc, char *argv[])
          FatalError.exit();
     }
 
-    const scalar scaleFactor = args.get<scalar>("scale", 1);
+    const scalar scaleFactor = args.getOrDefault<scalar>("scale", 1);
 
     const bool readBlank = !args.found("noBlank");
     const bool singleBlock = args.found("singleBlock");
diff --git a/applications/utilities/mesh/conversion/star4ToFoam/star4ToFoam.C b/applications/utilities/mesh/conversion/star4ToFoam/star4ToFoam.C
index f334f67063..24a6c28f70 100644
--- a/applications/utilities/mesh/conversion/star4ToFoam/star4ToFoam.C
+++ b/applications/utilities/mesh/conversion/star4ToFoam/star4ToFoam.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2016 OpenCFD Ltd.
+    Copyright (C) 2016-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -116,7 +116,7 @@ int main(int argc, char *argv[])
         prefix,
         runTime,
         // Default rescale from [mm] to [m]
-        args.get<scalar>("scale", 0.001),
+        args.getOrDefault<scalar>("scale", 0.001),
         args.found("solids")
     );
 
diff --git a/applications/utilities/mesh/generation/extrude/extrudeMesh/extrudeMesh.C b/applications/utilities/mesh/generation/extrude/extrudeMesh/extrudeMesh.C
index 2082ef5b50..26ad044ab6 100644
--- a/applications/utilities/mesh/generation/extrude/extrudeMesh/extrudeMesh.C
+++ b/applications/utilities/mesh/generation/extrude/extrudeMesh/extrudeMesh.C
@@ -250,7 +250,7 @@ int main(int argc, char *argv[])
                 IOobject::MUST_READ_IF_MODIFIED,
                 IOobject::NO_WRITE
             ),
-            args.get<fileName>("dict", "")
+            args.getOrDefault<fileName>("dict", "")
         )
     );
 
diff --git a/applications/utilities/mesh/generation/foamyMesh/foamyHexMesh/foamyHexMesh.C b/applications/utilities/mesh/generation/foamyMesh/foamyHexMesh/foamyHexMesh.C
index 94e9db0457..f9ce137867 100644
--- a/applications/utilities/mesh/generation/foamyMesh/foamyHexMesh/foamyHexMesh.C
+++ b/applications/utilities/mesh/generation/foamyMesh/foamyHexMesh/foamyHexMesh.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2016 OpenCFD Ltd.
+    Copyright (C) 2016-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -74,7 +74,7 @@ int main(int argc, char *argv[])
 
     // Allow override of decomposeParDict location
     const fileName decompDictFile =
-        args.get<fileName>("decomposeParDict", "");
+        args.getOrDefault<fileName>("decomposeParDict", "");
 
     IOdictionary foamyHexMeshDict
     (
diff --git a/applications/utilities/mesh/generation/foamyMesh/foamyHexMeshBackgroundMesh/foamyHexMeshBackgroundMesh.C b/applications/utilities/mesh/generation/foamyMesh/foamyHexMeshBackgroundMesh/foamyHexMeshBackgroundMesh.C
index d9122e9faa..19a0c25ad8 100644
--- a/applications/utilities/mesh/generation/foamyMesh/foamyHexMeshBackgroundMesh/foamyHexMeshBackgroundMesh.C
+++ b/applications/utilities/mesh/generation/foamyMesh/foamyHexMeshBackgroundMesh/foamyHexMeshBackgroundMesh.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2012-2016 OpenFOAM Foundation
-    Copyright (C) 2016 OpenCFD Ltd.
+    Copyright (C) 2016-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -64,7 +64,8 @@ scalar getMergeDistance
     const boundBox& bb
 )
 {
-    const scalar mergeTol = args.get<scalar>("mergeTol", defaultMergeTol);
+    const scalar mergeTol =
+        args.getOrDefault<scalar>("mergeTol", defaultMergeTol);
 
     scalar writeTol =
         Foam::pow(scalar(10), -scalar(IOstream::defaultPrecision()));
@@ -522,7 +523,7 @@ int main(int argc, char *argv[])
 
         // Allow override of decomposeParDict location
         const fileName decompDictFile =
-            args.get<fileName>("decomposeParDict", "");
+            args.getOrDefault<fileName>("decomposeParDict", "");
 
         labelList decomp = decompositionModel::New
         (
diff --git a/applications/utilities/mesh/generation/snappyHexMesh/snappyHexMesh.C b/applications/utilities/mesh/generation/snappyHexMesh/snappyHexMesh.C
index 7714baec17..c342fe88bd 100644
--- a/applications/utilities/mesh/generation/snappyHexMesh/snappyHexMesh.C
+++ b/applications/utilities/mesh/generation/snappyHexMesh/snappyHexMesh.C
@@ -894,7 +894,7 @@ int main(int argc, char *argv[])
                     IOobject::MUST_READ,
                     IOobject::NO_WRITE
                 ),
-                args.get<fileName>("decomposeParDict", "")
+                args.getOrDefault<fileName>("decomposeParDict", "")
             )
         );
 
@@ -1979,7 +1979,7 @@ int main(int argc, char *argv[])
 
         fileName outFileName
         (
-            args.get<fileName>
+            args.getOrDefault<fileName>
             (
                 "outFile",
                 "constant/triSurface/simplifiedSurface.stl"
diff --git a/applications/utilities/mesh/manipulation/checkMesh/checkMesh.C b/applications/utilities/mesh/manipulation/checkMesh/checkMesh.C
index 46869bd38b..8c6a557060 100644
--- a/applications/utilities/mesh/manipulation/checkMesh/checkMesh.C
+++ b/applications/utilities/mesh/manipulation/checkMesh/checkMesh.C
@@ -139,7 +139,7 @@ int main(int argc, char *argv[])
     const bool allTopology = args.found("allTopology");
     const bool meshQuality = args.found("meshQuality");
 
-    const word surfaceFormat = args.get<word>("writeSets", "");
+    const word surfaceFormat = args.getOrDefault<word>("writeSets", "");
     const bool writeSets = surfaceFormat.size();
 
     wordHashSet selectedFields;
diff --git a/applications/utilities/mesh/manipulation/createPatch/createPatch.C b/applications/utilities/mesh/manipulation/createPatch/createPatch.C
index ef476976b6..7e495c25f6 100644
--- a/applications/utilities/mesh/manipulation/createPatch/createPatch.C
+++ b/applications/utilities/mesh/manipulation/createPatch/createPatch.C
@@ -534,7 +534,7 @@ int main(int argc, char *argv[])
     #include "createTime.H"
 
     const word meshRegionName =
-        args.get<word>("region", polyMesh::defaultRegion);
+        args.getOrDefault<word>("region", polyMesh::defaultRegion);
 
     const bool overwrite = args.found("overwrite");
 
diff --git a/applications/utilities/mesh/manipulation/mergeMeshes/mergeMeshes.C b/applications/utilities/mesh/manipulation/mergeMeshes/mergeMeshes.C
index 936aae9ac9..92b38c546b 100644
--- a/applications/utilities/mesh/manipulation/mergeMeshes/mergeMeshes.C
+++ b/applications/utilities/mesh/manipulation/mergeMeshes/mergeMeshes.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2016-2017 OpenCFD Ltd.
+    Copyright (C) 2016-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -106,10 +106,10 @@ int main(int argc, char *argv[])
     fileName addCase = args[2];
 
     const word masterRegion =
-        args.get<word>("masterRegion", polyMesh::defaultRegion);
+        args.getOrDefault<word>("masterRegion", polyMesh::defaultRegion);
 
     const word addRegion =
-        args.get<word>("addRegion", polyMesh::defaultRegion);
+        args.getOrDefault<word>("addRegion", polyMesh::defaultRegion);
 
     // Since we don't use argList processor directory detection, add it to
     // the casename ourselves so it triggers the logic inside TimePath.
diff --git a/applications/utilities/mesh/manipulation/refineMesh/refineMesh.C b/applications/utilities/mesh/manipulation/refineMesh/refineMesh.C
index c5a1d9713e..83d789e884 100644
--- a/applications/utilities/mesh/manipulation/refineMesh/refineMesh.C
+++ b/applications/utilities/mesh/manipulation/refineMesh/refineMesh.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2018 OpenCFD Ltd.
+    Copyright (C) 2018-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -203,7 +203,7 @@ int main(int argc, char *argv[])
         const word dictName("refineMeshDict");
 
         // Obtain dictPath here for messages
-        fileName dictPath = args.get<fileName>("dict", "");
+        fileName dictPath = args.getOrDefault<fileName>("dict", "");
 
         IOobject dictIO = IOobject::selectIO
         (
diff --git a/applications/utilities/mesh/manipulation/transformPoints/transformPoints.C b/applications/utilities/mesh/manipulation/transformPoints/transformPoints.C
index 389024a517..7f695abffb 100644
--- a/applications/utilities/mesh/manipulation/transformPoints/transformPoints.C
+++ b/applications/utilities/mesh/manipulation/transformPoints/transformPoints.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2017-2019 OpenCFD Ltd.
+    Copyright (C) 2017-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -261,13 +261,13 @@ int main(int argc, char *argv[])
 
     if (args.found("time"))
     {
-        if (args.opt("time") == "constant")
+        if (args["time"] == "constant")
         {
             runTime.setTime(instant(0, "constant"), 0);
         }
         else
         {
-            scalar timeValue = args.get<scalar>("time");
+            const scalar timeValue = args.get<scalar>("time");
             runTime.setTime(instant(timeValue), 0);
         }
     }
diff --git a/applications/utilities/miscellaneous/foamDictionary/foamDictionary.C b/applications/utilities/miscellaneous/foamDictionary/foamDictionary.C
index 261665a7d6..97eeb2ccba 100644
--- a/applications/utilities/miscellaneous/foamDictionary/foamDictionary.C
+++ b/applications/utilities/miscellaneous/foamDictionary/foamDictionary.C
@@ -360,7 +360,7 @@ int main(int argc, char *argv[])
 
     // Set the default output precision
     {
-        const unsigned prec = args.lookupOrDefault<unsigned>("precision", 0u);
+        const unsigned prec = args.getOrDefault<unsigned>("precision", 0u);
         if (prec)
         {
             // if (Pstream::master())
diff --git a/applications/utilities/parallelProcessing/decomposePar/decomposePar.C b/applications/utilities/parallelProcessing/decomposePar/decomposePar.C
index e77ea9307e..4c94937c20 100644
--- a/applications/utilities/parallelProcessing/decomposePar/decomposePar.C
+++ b/applications/utilities/parallelProcessing/decomposePar/decomposePar.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2016-2018 OpenCFD Ltd.
+    Copyright (C) 2016-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -330,7 +330,8 @@ int main(int argc, char *argv[])
 
 
     // Allow override of decomposeParDict location
-    const fileName decompDictFile = args.get<fileName>("decomposeParDict", "");
+    const fileName decompDictFile =
+        args.getOrDefault<fileName>("decomposeParDict", "");
 
     // Get all region names
     wordList regionNames;
@@ -344,7 +345,8 @@ int main(int argc, char *argv[])
     else
     {
         regionNames.resize(1);
-        regionNames.first() = args.get<word>("region", fvMesh::defaultRegion);
+        regionNames.first() =
+            args.getOrDefault<word>("region", fvMesh::defaultRegion);
     }
 
     forAll(regionNames, regioni)
diff --git a/applications/utilities/parallelProcessing/reconstructParMesh/reconstructParMesh.C b/applications/utilities/parallelProcessing/reconstructParMesh/reconstructParMesh.C
index e3f8eae58b..e4f717f682 100644
--- a/applications/utilities/parallelProcessing/reconstructParMesh/reconstructParMesh.C
+++ b/applications/utilities/parallelProcessing/reconstructParMesh/reconstructParMesh.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2016-2017 OpenCFD Ltd.
+    Copyright (C) 2016-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -509,7 +509,8 @@ int main(int argc, char *argv[])
         Info<< "Operating on region " << regionName << nl << endl;
     }
 
-    const scalar mergeTol = args.get<scalar>("mergeTol", defaultMergeTol);
+    const scalar mergeTol =
+        args.getOrDefault<scalar>("mergeTol", defaultMergeTol);
 
     scalar writeTol = Foam::pow(10.0, -scalar(IOstream::defaultPrecision()));
 
diff --git a/applications/utilities/parallelProcessing/redistributePar/redistributePar.C b/applications/utilities/parallelProcessing/redistributePar/redistributePar.C
index de0fdd7fad..a7facbdf04 100644
--- a/applications/utilities/parallelProcessing/redistributePar/redistributePar.C
+++ b/applications/utilities/parallelProcessing/redistributePar/redistributePar.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2015-2018 OpenCFD Ltd.
+    Copyright (C) 2015-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -119,7 +119,8 @@ scalar getMergeDistance
     const boundBox& bb
 )
 {
-    const scalar mergeTol = args.get<scalar>("mergeTol", defaultMergeTol);
+    const scalar mergeTol =
+        args.getOrDefault<scalar>("mergeTol", defaultMergeTol);
 
     const scalar writeTol =
         Foam::pow(scalar(10), -scalar(IOstream::defaultPrecision()));
@@ -2500,7 +2501,8 @@ int main(int argc, char *argv[])
 
 
     // Allow override of decomposeParDict location
-    const fileName decompDictFile = args.get<fileName>("decomposeParDict", "");
+    const fileName decompDictFile =
+        args.getOrDefault<fileName>("decomposeParDict", "");
 
     // Get all region names
     wordList regionNames;
@@ -2514,7 +2516,8 @@ int main(int argc, char *argv[])
     else
     {
         regionNames.resize(1);
-        regionNames.first() = args.get<word>("region", fvMesh::defaultRegion);
+        regionNames.first() =
+            args.getOrDefault<word>("region", fvMesh::defaultRegion);
     }
 
 
diff --git a/applications/utilities/postProcessing/dataConversion/foamToEnsight/foamToEnsight.C b/applications/utilities/postProcessing/dataConversion/foamToEnsight/foamToEnsight.C
index dd5d4dbf8f..1eb31e4130 100644
--- a/applications/utilities/postProcessing/dataConversion/foamToEnsight/foamToEnsight.C
+++ b/applications/utilities/postProcessing/dataConversion/foamToEnsight/foamToEnsight.C
@@ -357,7 +357,7 @@ int main(int argc, char *argv[])
 
     // Forced point interpolation?
     caseOpts.nodeValues(doPointValues && args.found("nodeValues"));
-    caseOpts.width(args.get<label>("width", 8));
+    caseOpts.width(args.getOrDefault<label>("width", 8));
     caseOpts.overwrite(!args.found("no-overwrite")); // Remove existing?
 
     // Can also have separate directory for lagrangian
@@ -366,7 +366,7 @@ int main(int argc, char *argv[])
     // Define sub-directory name to use for EnSight data.
     // The path to the ensight directory is at case level only
     // - For parallel cases, data only written from master
-    fileName outputDir = args.get<word>("name", "EnSight");
+    fileName outputDir = args.getOrDefault<word>("name", "EnSight");
     if (!outputDir.isAbsolute())
     {
         outputDir = args.globalPath()/outputDir;
diff --git a/applications/utilities/postProcessing/dataConversion/foamToVTK/foamToVTK.C b/applications/utilities/postProcessing/dataConversion/foamToVTK/foamToVTK.C
index eb2514f37b..1a5da07739 100644
--- a/applications/utilities/postProcessing/dataConversion/foamToVTK/foamToVTK.C
+++ b/applications/utilities/postProcessing/dataConversion/foamToVTK/foamToVTK.C
@@ -633,7 +633,8 @@ int main(int argc, char *argv[])
     else
     {
         regionNames.resize(1);
-        regionNames.first() = args.get<word>("region", fvMesh::defaultRegion);
+        regionNames.first() =
+            args.getOrDefault<word>("region", fvMesh::defaultRegion);
     }
 
 
@@ -695,7 +696,7 @@ int main(int argc, char *argv[])
     // Directory management
 
     // Sub-directory for output
-    const word vtkDirName = args.get<word>("name", "VTK");
+    const word vtkDirName = args.getOrDefault<word>("name", "VTK");
 
     const fileName outputDir(args.globalPath()/vtkDirName);
 
diff --git a/applications/utilities/postProcessing/lumped/lumpedPointMovement/lumpedPointMovement.C b/applications/utilities/postProcessing/lumped/lumpedPointMovement/lumpedPointMovement.C
index 04618b0edf..a6ca67f851 100644
--- a/applications/utilities/postProcessing/lumped/lumpedPointMovement/lumpedPointMovement.C
+++ b/applications/utilities/postProcessing/lumped/lumpedPointMovement/lumpedPointMovement.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016-2017 OpenCFD Ltd.
+    Copyright (C) 2016-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -93,10 +93,10 @@ int main(int argc, char *argv[])
 
     #include "setRootCase.H"
 
-    const label maxOut = Foam::max(0, args.get<label>("max", 0));
-    const label span   = Foam::max(1, args.get<label>("span", 1));
+    const label maxOut = Foam::max(0, args.getOrDefault<label>("max", 0));
+    const label span   = Foam::max(1, args.getOrDefault<label>("span", 1));
 
-    const scalar relax = args.get<scalar>("scale", 1);
+    const scalar relax = args.getOrDefault<scalar>("scale", 1);
 
     const bool slave = args.found("slave");
     const bool removeLock = args.found("removeLock");
diff --git a/applications/utilities/postProcessing/miscellaneous/temporalInterpolate/temporalInterpolate.C b/applications/utilities/postProcessing/miscellaneous/temporalInterpolate/temporalInterpolate.C
index 185b153232..be8f32bced 100644
--- a/applications/utilities/postProcessing/miscellaneous/temporalInterpolate/temporalInterpolate.C
+++ b/applications/utilities/postProcessing/miscellaneous/temporalInterpolate/temporalInterpolate.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2015 OpenFOAM Foundation
-    Copyright (C) 2018 OpenCFD Ltd.
+    Copyright (C) 2018-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -237,12 +237,12 @@ int main(int argc, char *argv[])
     }
 
 
-    const int divisions = args.get<int>("divisions", 1);
+    const int divisions = args.getOrDefault<int>("divisions", 1);
     Info<< "Using " << divisions << " per time interval" << nl << endl;
 
 
     const word interpolationType =
-        args.get<word>("interpolationType", "linear");
+        args.getOrDefault<word>("interpolationType", "linear");
 
     Info<< "Using interpolation " << interpolationType << nl << endl;
 
diff --git a/applications/utilities/preProcessing/createZeroDirectory/createZeroDirectory.C b/applications/utilities/preProcessing/createZeroDirectory/createZeroDirectory.C
index fc70e5ccdb..5c09e1bbd6 100644
--- a/applications/utilities/preProcessing/createZeroDirectory/createZeroDirectory.C
+++ b/applications/utilities/preProcessing/createZeroDirectory/createZeroDirectory.C
@@ -250,7 +250,7 @@ int main(int argc, char *argv[])
 
     fileName baseDir
     (
-        args.get<fileName>
+        args.getOrDefault<fileName>
         (
             "templateDir",
             "${WM_PROJECT_DIR}/etc/caseDicts/createZeroDirectoryTemplates"
diff --git a/applications/utilities/preProcessing/foamUpgradeCyclics/foamUpgradeCyclics.C b/applications/utilities/preProcessing/foamUpgradeCyclics/foamUpgradeCyclics.C
index 1ffe28cae3..5b508cc37b 100644
--- a/applications/utilities/preProcessing/foamUpgradeCyclics/foamUpgradeCyclics.C
+++ b/applications/utilities/preProcessing/foamUpgradeCyclics/foamUpgradeCyclics.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2019 OpenCFD Ltd.
+    Copyright (C) 2019-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -434,7 +434,8 @@ int main(int argc, char *argv[])
     }
     const bool enableEntries = args.found("enableFunctionEntries");
 
-    const word regionName = args.get<word>("region", polyMesh::defaultRegion);
+    const word regionName =
+        args.getOrDefault<word>("region", polyMesh::defaultRegion);
 
     fileName regionPrefix;
     if (regionName != polyMesh::defaultRegion)
diff --git a/applications/utilities/preProcessing/mapFields/mapFields.C b/applications/utilities/preProcessing/mapFields/mapFields.C
index 1216b0fbaa..9e7b984745 100644
--- a/applications/utilities/preProcessing/mapFields/mapFields.C
+++ b/applications/utilities/preProcessing/mapFields/mapFields.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2018 OpenCFD Ltd.
+    Copyright (C) 2018-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -69,7 +69,7 @@ int readNumProcs
                     IOobject::NO_WRITE,
                     false // do not register
                 ),
-                args.get<fileName>(optionName, "")
+                args.getOrDefault<fileName>(optionName, "")
             )
         )
     );
diff --git a/applications/utilities/preProcessing/setExprFields/setExprFields.C b/applications/utilities/preProcessing/setExprFields/setExprFields.C
index 21a609124c..2b995e0c31 100644
--- a/applications/utilities/preProcessing/setExprFields/setExprFields.C
+++ b/applications/utilities/preProcessing/setExprFields/setExprFields.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019 OpenCFD Ltd.
+    Copyright (C) 2019-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -771,7 +771,7 @@ int main(int argc, char *argv[])
             expressions::exprString
                 expression
                 (
-                    args.opt("expression"),
+                    args[expression],
                     dictionary::null
                 );
 
diff --git a/applications/utilities/surface/surfaceAdd/surfaceAdd.C b/applications/utilities/surface/surfaceAdd/surfaceAdd.C
index 993d84d49c..6195dd3c68 100644
--- a/applications/utilities/surface/surfaceAdd/surfaceAdd.C
+++ b/applications/utilities/surface/surfaceAdd/surfaceAdd.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2016 OpenCFD Ltd.
+    Copyright (C) 2016-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -90,7 +90,7 @@ int main(int argc, char *argv[])
     const bool addPoint     = args.found("points");
     const bool mergeRegions = args.found("mergeRegions");
 
-    const scalar scaleFactor = args.get<scalar>("scale", -1);
+    const scalar scaleFactor = args.getOrDefault<scalar>("scale", -1);
 
     if (addPoint)
     {
diff --git a/applications/utilities/surface/surfaceBooleanFeatures/surfaceBooleanFeatures.C b/applications/utilities/surface/surfaceBooleanFeatures/surfaceBooleanFeatures.C
index 2f61b9a52c..174ae4367a 100644
--- a/applications/utilities/surface/surfaceBooleanFeatures/surfaceBooleanFeatures.C
+++ b/applications/utilities/surface/surfaceBooleanFeatures/surfaceBooleanFeatures.C
@@ -1606,7 +1606,7 @@ int main(int argc, char *argv[])
 
 
     // Scale factor for both surfaces:
-    const scalar scaleFactor = args.get<scalar>("scale", -1);
+    const scalar scaleFactor = args.getOrDefault<scalar>("scale", -1);
 
     const word surf1Name(args[2]);
     Info<< "Reading surface " << surf1Name << endl;
diff --git a/applications/utilities/surface/surfaceCheck/surfaceCheck.C b/applications/utilities/surface/surfaceCheck/surfaceCheck.C
index 0305a35635..d7492379ba 100644
--- a/applications/utilities/surface/surfaceCheck/surfaceCheck.C
+++ b/applications/utilities/surface/surfaceCheck/surfaceCheck.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2016-2019 OpenCFD Ltd.
+    Copyright (C) 2016-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -338,8 +338,9 @@ int main(int argc, char *argv[])
     const fileName surfFileName = args[1];
     const bool checkSelfIntersect = args.found("checkSelfIntersection");
     const bool splitNonManifold = args.found("splitNonManifold");
-    const label outputThreshold = args.get<label>("outputThreshold", 10);
-    const word surfaceFormat = args.get<word>("writeSets", "");
+    const label outputThreshold =
+        args.getOrDefault<label>("outputThreshold", 10);
+    const word surfaceFormat = args.getOrDefault<word>("writeSets", "");
     const bool writeSets = !surfaceFormat.empty();
 
     autoPtr<surfaceWriter> surfWriter;
diff --git a/applications/utilities/surface/surfaceClean/surfaceClean.C b/applications/utilities/surface/surfaceClean/surfaceClean.C
index 028054c231..ce0a7c10b9 100644
--- a/applications/utilities/surface/surfaceClean/surfaceClean.C
+++ b/applications/utilities/surface/surfaceClean/surfaceClean.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2013 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -96,7 +97,7 @@ int main(int argc, char *argv[])
     triSurface surf
     (
         inFileName,
-        args.get<scalar>("scale", -1)
+        args.getOrDefault<scalar>("scale", -1)
     );
     surf.writeStats(Info);
 
diff --git a/applications/utilities/surface/surfaceCoarsen/surfaceCoarsen.C b/applications/utilities/surface/surfaceCoarsen/surfaceCoarsen.C
index 71edd76366..1adad6a7f8 100644
--- a/applications/utilities/surface/surfaceCoarsen/surfaceCoarsen.C
+++ b/applications/utilities/surface/surfaceCoarsen/surfaceCoarsen.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -104,7 +105,7 @@ int main(int argc, char *argv[])
             << exit(FatalError);
     }
 
-    const scalar scaleFactor = args.get<scalar>("scale", -1);
+    const scalar scaleFactor = args.getOrDefault<scalar>("scale", -1);
 
     Info<< "Input surface   :" << inFileName << nl
         << "Scaling factor  :" << scaleFactor << nl
diff --git a/applications/utilities/surface/surfaceConvert/surfaceConvert.C b/applications/utilities/surface/surfaceConvert/surfaceConvert.C
index c1707c4a87..f65f316f8d 100644
--- a/applications/utilities/surface/surfaceConvert/surfaceConvert.C
+++ b/applications/utilities/surface/surfaceConvert/surfaceConvert.C
@@ -149,7 +149,7 @@ int main(int argc, char *argv[])
     argList args(argc, argv);
 
     {
-        const unsigned prec = args.lookupOrDefault<unsigned>("precision", 0u);
+        const unsigned prec = args.getOrDefault<unsigned>("precision", 0u);
         if (prec)
         {
             Info<< "Output write precision set to " << prec << endl;
diff --git a/applications/utilities/surface/surfaceFind/surfaceFind.C b/applications/utilities/surface/surfaceFind/surfaceFind.C
index e9ace78a1c..e23ce76847 100644
--- a/applications/utilities/surface/surfaceFind/surfaceFind.C
+++ b/applications/utilities/surface/surfaceFind/surfaceFind.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -63,9 +64,9 @@ int main(int argc, char *argv[])
 
     const point samplePt
     (
-        args.get<scalar>("x", 0),
-        args.get<scalar>("y", 0),
-        args.get<scalar>("z", 0)
+        args.getOrDefault<scalar>("x", 0),
+        args.getOrDefault<scalar>("y", 0),
+        args.getOrDefault<scalar>("z", 0)
     );
     Info<< "Looking for nearest face/vertex to " << samplePt << endl;
 
diff --git a/applications/utilities/surface/surfaceInertia/surfaceInertia.C b/applications/utilities/surface/surfaceInertia/surfaceInertia.C
index f0cf7de59b..7147ce4656 100644
--- a/applications/utilities/surface/surfaceInertia/surfaceInertia.C
+++ b/applications/utilities/surface/surfaceInertia/surfaceInertia.C
@@ -89,7 +89,7 @@ int main(int argc, char *argv[])
     argList args(argc, argv);
 
     const fileName surfFileName = args[1];
-    const scalar density = args.get<scalar>("density", 1);
+    const scalar density = args.getOrDefault<scalar>("density", 1);
 
     vector refPt = Zero;
     bool calcAroundRefPt = args.readIfPresent("referencePoint", refPt);
diff --git a/applications/utilities/surface/surfaceInflate/surfaceInflate.C b/applications/utilities/surface/surfaceInflate/surfaceInflate.C
index 58ee30a9af..333533f2fa 100644
--- a/applications/utilities/surface/surfaceInflate/surfaceInflate.C
+++ b/applications/utilities/surface/surfaceInflate/surfaceInflate.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2015 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -612,8 +613,8 @@ int main(int argc, char *argv[])
     const scalar distance(args.get<scalar>(2));
     const scalar extendFactor(args.get<scalar>(3));
     const bool checkSelfIntersect = args.found("checkSelfIntersection");
-    const label nSmooth = args.get<label>("nSmooth", 10);
-    const scalar featureAngle = args.get<scalar>("featureAngle", 180);
+    const label nSmooth = args.getOrDefault<label>("nSmooth", 10);
+    const scalar featureAngle = args.getOrDefault<scalar>("featureAngle", 180);
     const bool debug = args.found("debug");
 
 
diff --git a/applications/utilities/surface/surfaceMeshConvert/surfaceMeshConvert.C b/applications/utilities/surface/surfaceMeshConvert/surfaceMeshConvert.C
index 007f2a2940..b2257f39f1 100644
--- a/applications/utilities/surface/surfaceMeshConvert/surfaceMeshConvert.C
+++ b/applications/utilities/surface/surfaceMeshConvert/surfaceMeshConvert.C
@@ -230,7 +230,7 @@ int main(int argc, char *argv[])
                 IOobject::NO_WRITE,
                 false
             ),
-            args.get<fileName>("dict", "")
+            args.getOrDefault<fileName>("dict", "")
         );
 
         if (!ioCsys.typeHeaderOk<coordinateSystems>(false))
diff --git a/applications/utilities/surface/surfaceMeshExport/surfaceMeshExport.C b/applications/utilities/surface/surfaceMeshExport/surfaceMeshExport.C
index d1d8728dc6..9430397e41 100644
--- a/applications/utilities/surface/surfaceMeshExport/surfaceMeshExport.C
+++ b/applications/utilities/surface/surfaceMeshExport/surfaceMeshExport.C
@@ -156,7 +156,7 @@ int main(int argc, char *argv[])
     Time runTime(args.rootPath(), args.caseName());
 
     const fileName exportName(args[1]);
-    const word importName(args.get<word>("name", "default"));
+    const word importName(args.getOrDefault<word>("name", "default"));
 
     const word writeFileType
     (
@@ -191,7 +191,7 @@ int main(int argc, char *argv[])
                 IOobject::NO_WRITE,
                 false
             ),
-            args.get<fileName>("dict", "")
+            args.getOrDefault<fileName>("dict", "")
         );
 
         if (!ioCsys.typeHeaderOk<coordinateSystems>(false))
diff --git a/applications/utilities/surface/surfaceMeshImport/surfaceMeshImport.C b/applications/utilities/surface/surfaceMeshImport/surfaceMeshImport.C
index 339224b75a..0731744f02 100644
--- a/applications/utilities/surface/surfaceMeshImport/surfaceMeshImport.C
+++ b/applications/utilities/surface/surfaceMeshImport/surfaceMeshImport.C
@@ -168,7 +168,7 @@ int main(int argc, char *argv[])
 
 
     const fileName importName(args[1]);
-    const word exportName(args.get<word>("name", "default"));
+    const word exportName(args.getOrDefault<word>("name", "default"));
 
     const word readFileType
     (
@@ -203,7 +203,7 @@ int main(int argc, char *argv[])
                 IOobject::NO_WRITE,
                 false
             ),
-            args.get<fileName>("dict", "")
+            args.getOrDefault<fileName>("dict", "")
         );
 
         if (!ioCsys.typeHeaderOk<coordinateSystems>(false))
diff --git a/applications/utilities/surface/surfaceMeshInfo/surfaceMeshInfo.C b/applications/utilities/surface/surfaceMeshInfo/surfaceMeshInfo.C
index be784b9f2c..6409990bfd 100644
--- a/applications/utilities/surface/surfaceMeshInfo/surfaceMeshInfo.C
+++ b/applications/utilities/surface/surfaceMeshInfo/surfaceMeshInfo.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2016 OpenCFD Ltd.
+    Copyright (C) 2016-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -122,7 +122,7 @@ int main(int argc, char *argv[])
     // use UnsortedMeshedSurface, not MeshedSurface to maintain ordering
     UnsortedMeshedSurface<face> surf(importName);
 
-    const scalar scaling = args.get<scalar>("scale", -1);
+    const scalar scaling = args.getOrDefault<scalar>("scale", -1);
     if (scaling > 0)
     {
         DetailInfo << " -scale " << scaling << nl;
diff --git a/applications/utilities/surface/surfaceOrient/surfaceOrient.C b/applications/utilities/surface/surfaceOrient/surfaceOrient.C
index 438aed66e5..4158dc04d9 100644
--- a/applications/utilities/surface/surfaceOrient/surfaceOrient.C
+++ b/applications/utilities/surface/surfaceOrient/surfaceOrient.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2013 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -95,7 +96,7 @@ int main(int argc, char *argv[])
         Info<< "outside" << endl;
     }
 
-    const scalar scaling = args.get<scalar>("scale", -1);
+    const scalar scaling = args.getOrDefault<scalar>("scale", -1);
     if (scaling > 0)
     {
         Info<< "Input scaling: " << scaling << nl;
diff --git a/applications/utilities/surface/surfacePointMerge/surfacePointMerge.C b/applications/utilities/surface/surfacePointMerge/surfacePointMerge.C
index ef3d80bb91..954a5064d9 100644
--- a/applications/utilities/surface/surfacePointMerge/surfacePointMerge.C
+++ b/applications/utilities/surface/surfacePointMerge/surfacePointMerge.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2013 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -70,7 +71,7 @@ int main(int argc, char *argv[])
     const scalar   mergeTol = args.get<scalar>(2);
     const fileName outFileName = args[3];
 
-    const scalar scaling = args.get<scalar>("scale", -1);
+    const scalar scaling = args.getOrDefault<scalar>("scale", -1);
 
     Info<< "Reading surface from " << surfFileName << " ..." << nl
         << "Merging points within " << mergeTol << " metre." << nl;
diff --git a/applications/utilities/surface/surfaceRedistributePar/surfaceRedistributePar.C b/applications/utilities/surface/surfaceRedistributePar/surfaceRedistributePar.C
index 38a772bdf6..7b9824c0b0 100644
--- a/applications/utilities/surface/surfaceRedistributePar/surfaceRedistributePar.C
+++ b/applications/utilities/surface/surfaceRedistributePar/surfaceRedistributePar.C
@@ -177,7 +177,7 @@ int main(int argc, char *argv[])
                     IOobject::MUST_READ,
                     IOobject::NO_WRITE
                 ),
-                args.get<fileName>("decomposeParDict", "")
+                args.getOrDefault<fileName>("decomposeParDict", "")
             )
         );
 
diff --git a/applications/utilities/surface/surfaceToPatch/surfaceToPatch.C b/applications/utilities/surface/surfaceToPatch/surfaceToPatch.C
index 659ed93f93..8a78994144 100644
--- a/applications/utilities/surface/surfaceToPatch/surfaceToPatch.C
+++ b/applications/utilities/surface/surfaceToPatch/surfaceToPatch.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -213,7 +214,7 @@ int main(int argc, char *argv[])
             << " triangle ..." << endl;
     }
 
-    const scalar searchTol = args.get<scalar>("tol", 1e-3);
+    const scalar searchTol = args.getOrDefault<scalar>("tol", 1e-3);
 
     // Get search box. Anything not within this box will not be considered.
     const boundBox& meshBb = mesh.bounds();
diff --git a/src/OpenFOAM/db/functionObjects/functionObjectList/functionObjectList.C b/src/OpenFOAM/db/functionObjects/functionObjectList/functionObjectList.C
index 32795b9c4c..d62d1ae476 100644
--- a/src/OpenFOAM/db/functionObjects/functionObjectList/functionObjectList.C
+++ b/src/OpenFOAM/db/functionObjects/functionObjectList/functionObjectList.C
@@ -333,7 +333,7 @@ bool Foam::functionObjectList::readFunctionObject
     }
 
     // Insert the region name if specified
-    if (region != word::null)
+    if (!region.empty())
     {
         funcDict.set("region", region);
     }
@@ -403,7 +403,7 @@ Foam::autoPtr<Foam::functionObjectList> Foam::functionObjectList::New
 
     dictionary& functionsDict = controlDict.subDict("functions");
 
-    const word regionName = args.get<word>("region", "");
+    const word regionName = args.getOrDefault<word>("region", "");
 
     bool modifiedControlDict = false;
 
diff --git a/src/OpenFOAM/global/argList/argList.C b/src/OpenFOAM/global/argList/argList.C
index 76f3c03668..feea556952 100644
--- a/src/OpenFOAM/global/argList/argList.C
+++ b/src/OpenFOAM/global/argList/argList.C
@@ -288,6 +288,16 @@ void Foam::argList::checkITstream(const ITstream& is, const word& optName)
 }
 
 
+void Foam::argList::raiseBadInput(const word& optName) const
+{
+    // Can use FatalError
+    // predicate checks are not used at the earliest stages
+    FatalErrorIn(executable())
+        << "Option -" << optName << " with invalid input" << nl
+        << exit(FatalError);
+}
+
+
 void Foam::argList::addArgument
 (
     const string& argName,
diff --git a/src/OpenFOAM/global/argList/argList.H b/src/OpenFOAM/global/argList/argList.H
index 39c63b209f..38dd63fea7 100644
--- a/src/OpenFOAM/global/argList/argList.H
+++ b/src/OpenFOAM/global/argList/argList.H
@@ -176,6 +176,9 @@ class argList
         template<class T>
         static inline void readList(ITstream& is, List<T>& list);
 
+        //- Trigger FatalError for given option
+        void raiseBadInput(const word& optName) const;
+
         //- Set rootPath_, globalCase_, case_ from one of the following forms
         //   * [-case dir]
         //   * cwd
@@ -392,9 +395,16 @@ public:
         inline T get(const word& optName) const;
 
         //- Get a value from the named option if present, or return default.
-        //  Identical to getOrDefault().
         template<class T>
-        inline T get(const word& optName, const T& deflt) const;
+        inline T getOrDefault(const word& optName, const T& deflt) const;
+
+        //- Get a List of values from the named option,
+        //- treating a single entry like a list of size 1.
+        //  \param optName  the option name to read from
+        //  \param mandatory if the option is non-mandatory, the behaviour
+        //      is similar to readListIfPresent().
+        template<class T>
+        inline List<T> getList(const word& optName, bool mandatory=true) const;
 
         //- Read a value from the named option if present.
         //  \return true if the named option was found.
@@ -412,38 +422,72 @@ public:
             const T& deflt
         ) const;
 
-        //- Get a value from the named option if present, or return default.
-        template<class T>
-        inline T getOrDefault(const word& optName, const T& deflt) const;
-
-        //- Get a List of values from the named option,
-        //- treating a single entry like a list of size 1.
-        //  \param optName  the option name to read from
-        //  \param mandatory if the option is non-mandatory, the behaviour
-        //      is similar to readListIfPresent().
-        template<class T>
-        inline List<T> getList(const word& optName, bool mandatory=true) const;
-
         //- If named option is present, get a List of values
         //- treating a single entry like a list of size 1.
         //  \return true if the named option was found.
         template<class T>
         inline bool readListIfPresent(const word& optName, List<T>& list) const;
 
+        //- Read the named option and check its validity.
+        //  FatalError if mandatory and not found, or if the predicate check
+        //  failed.
+        //
+        //  \param optName the option name
+        //  \param val the value to read into
+        //  \param pred the value check predicate
+        //
+        //  \return true if the entry was found.
+        template<class T, class Predicate>
+        inline bool readCheck
+        (
+            const word& optName,
+            T& val,
+            const Predicate& pred,
+            bool mandatory = true
+        ) const;
 
-        //- Alternative name for option get(const word& optName)
-        template<class T=string>
-        T opt(const word& optName) const
-        {
-            return this->get<T>(optName);
-        }
+        //- Read the named option if present and check its validity.
+        //  FatalError if found and the predicate check failed.
+        //
+        //  \param optName the option name
+        //  \param val the value to read into
+        //  \param pred the value check predicate
+        //
+        //  \return true if the entry was found.
+        template<class T, class Predicate>
+        inline bool readCheckIfPresent
+        (
+            const word& optName,
+            T& val,
+            const Predicate& pred
+        ) const;
 
-        //- Alternative name for option get(const word& optName, ...)
-        template<class T>
-        T opt(const word& optName, const T& deflt) const
-        {
-            return this->get<T>(optName, deflt);
-        }
+        //- Get a value from the named option with additional checking.
+        //  FatalError if the predicate check failed.
+        //
+        //  \param optName the option name
+        //  \param pred the value check predicate
+        template<class T, class Predicate>
+        T getCheck
+        (
+            const word& optName,
+            const Predicate& pred
+        ) const;
+
+        //- Get a value from the named option with additional checking
+        //- (if present), or return default.
+        //  FatalError if the predicate check on the retrieved value failed.
+        //
+        //  \param optName the option name
+        //  \param deflt the default return value
+        //  \param pred the value check predicate
+        template<class T, class Predicate>
+        T getCheckOrDefault
+        (
+            const word& optName,
+            const T& deflt,
+            const Predicate& pred
+        ) const;
 
 
     // Edit
@@ -612,11 +656,36 @@ public:
 
     // Housekeeping
 
-        //- Get a value from the named option if present, or return default.
+        //- Deprecated(2020-05) identical to get(const word& optName)
+        //  \deprecated(2020-05) - use get() method
+        template<class T=string>
+        T opt(const word& optName) const
+        {
+            return this->get<T>(optName);
+        }
+
+        //- Deprecated(2020-05) identical to getOrDefault(...)
+        //  \deprecated(2020-05) - use getOrDefault() method
+        template<class T>
+        T opt(const word& optName, const T& deflt) const
+        {
+            return this->getOrDefault<T>(optName, deflt);
+        }
+
+        //- Deprecated(2020-05) identical to getOrDefault(...)
+        //  \deprecated(2020-05) - use getOrDefault() method
+        template<class T>
+        T get(const word& optName, const T& deflt) const
+        {
+            return this->getOrDefault<T>(optName, deflt);
+        }
+
+        //- Deprecated(2020-05) identical to getOrDefault(...)
+        //  \deprecated(2020-05) - use getOrDefault() method
         template<class T>
         T lookupOrDefault(const word& optName, const T& deflt) const
         {
-            return getOrDefault<T>(optName, deflt);
+            return this->getOrDefault<T>(optName, deflt);
         }
 
 
diff --git a/src/OpenFOAM/global/argList/argListI.H b/src/OpenFOAM/global/argList/argListI.H
index d3f5f53e04..6e78c3afa4 100644
--- a/src/OpenFOAM/global/argList/argListI.H
+++ b/src/OpenFOAM/global/argList/argListI.H
@@ -282,7 +282,11 @@ inline T Foam::argList::get(const word& optName) const
 
 
 template<class T>
-inline T Foam::argList::get(const word& optName, const T& deflt) const
+inline T Foam::argList::getOrDefault
+(
+    const word& optName,
+    const T& deflt
+) const
 {
     if (found(optName))
     {
@@ -328,22 +332,6 @@ inline bool Foam::argList::readIfPresent
 }
 
 
-template<class T>
-inline T Foam::argList::getOrDefault
-(
-    const word& optName,
-    const T& deflt
-) const
-{
-    if (found(optName))
-    {
-        return get<T>(optName);
-    }
-
-    return deflt;
-}
-
-
 template<class T>
 inline Foam::List<T> Foam::argList::getList(const label index) const
 {
@@ -402,6 +390,80 @@ inline bool Foam::argList::readListIfPresent
 }
 
 
+template<class T, class Predicate>
+inline bool Foam::argList::readCheck
+(
+    const word& optName,
+    T& val,
+    const Predicate& pred,
+    bool mandatory
+) const
+{
+    if (readIfPresent<T>(optName, val))
+    {
+        if (!pred(val))
+        {
+            raiseBadInput(optName);
+        }
+
+        return true;
+    }
+    else if (mandatory)
+    {
+        FatalError(executable())
+            << "Option -" << optName << " not specified" << nl
+            << exit(FatalError);
+    }
+
+    return false;
+}
+
+
+template<class T, class Predicate>
+inline bool Foam::argList::readCheckIfPresent
+(
+    const word& optName,
+    T& val,
+    const Predicate& pred
+) const
+{
+    return readCheck<T>(optName, val, pred, false);
+}
+
+
+template<class T, class Predicate>
+inline T Foam::argList::getCheck
+(
+    const word& optName,
+    const Predicate& pred
+) const
+{
+    T val;
+    readCheck<T>(optName, val, pred, true);
+    return val;
+}
+
+
+template<class T, class Predicate>
+inline T Foam::argList::getCheckOrDefault
+(
+    const word& optName,
+    const T& deflt,
+    const Predicate& pred
+) const
+{
+    // Could predicate check default as well (for FULLDEBUG)
+
+    T val;
+    if (readCheck<T>(optName, val, pred, false))
+    {
+        return val;
+    }
+
+    return deflt;
+}
+
+
 // * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //
 
 inline const Foam::string& Foam::argList::operator[](const label index) const
diff --git a/src/OpenFOAM/include/setConstantMeshDictionaryIO.H b/src/OpenFOAM/include/setConstantMeshDictionaryIO.H
index 0ea2f3397d..66bcea2c7e 100644
--- a/src/OpenFOAM/include/setConstantMeshDictionaryIO.H
+++ b/src/OpenFOAM/include/setConstantMeshDictionaryIO.H
@@ -8,5 +8,5 @@ IOobject dictIO = IOobject::selectIO
         IOobject::MUST_READ_IF_MODIFIED,
         IOobject::NO_WRITE
     ),
-    args.get<fileName>("dict", "")
+    args.getOrDefault<fileName>("dict", "")
 );
diff --git a/src/OpenFOAM/include/setConstantRunTimeDictionaryIO.H b/src/OpenFOAM/include/setConstantRunTimeDictionaryIO.H
index a42b433ffe..902351e054 100644
--- a/src/OpenFOAM/include/setConstantRunTimeDictionaryIO.H
+++ b/src/OpenFOAM/include/setConstantRunTimeDictionaryIO.H
@@ -8,5 +8,5 @@ IOobject dictIO = IOobject::selectIO
         IOobject::MUST_READ_IF_MODIFIED,
         IOobject::NO_WRITE
     ),
-    args.get<fileName>("dict", "")
+    args.getOrDefault<fileName>("dict", "")
 );
diff --git a/src/OpenFOAM/include/setSystemMeshDictionaryIO.H b/src/OpenFOAM/include/setSystemMeshDictionaryIO.H
index 6cd54c20a2..ca1c2ebbe9 100644
--- a/src/OpenFOAM/include/setSystemMeshDictionaryIO.H
+++ b/src/OpenFOAM/include/setSystemMeshDictionaryIO.H
@@ -8,5 +8,5 @@ IOobject dictIO = IOobject::selectIO
         IOobject::MUST_READ_IF_MODIFIED,
         IOobject::NO_WRITE
     ),
-    args.get<fileName>("dict", "")
+    args.getOrDefault<fileName>("dict", "")
 );
diff --git a/src/OpenFOAM/include/setSystemRunTimeDictionaryIO.H b/src/OpenFOAM/include/setSystemRunTimeDictionaryIO.H
index 05b5ed4d7b..016143a70e 100644
--- a/src/OpenFOAM/include/setSystemRunTimeDictionaryIO.H
+++ b/src/OpenFOAM/include/setSystemRunTimeDictionaryIO.H
@@ -8,5 +8,5 @@ IOobject dictIO = IOobject::selectIO
         IOobject::MUST_READ_IF_MODIFIED,
         IOobject::NO_WRITE
     ),
-    args.get<fileName>("dict", "")
+    args.getOrDefault<fileName>("dict", "")
 );