Why is our Space-Time 4-Dimensional?

In this 21st Century, we should claim that we live in the quantum 4-dimensional Minkowski space-time. We wish to "show" that the Standard Model is determined by this quantum 4-dimensional Minkowski space-time, through the dimensionlessness of all the couplings. Thus, we believe that the quantum 4-dimensional Minkowski space-time with the force-fields gauge-group structure SUc (3) x SUL (2) x U(1) x SUf (3) built-in from the very beginning is the background for everything. The lepton world, of atomic sizes, is accepted by this background and offers us the eyes to see other things. The quark world, of the Fermi sizes, also accepted by the background, makes this entire world much more interesting. Unfortunately, we still don't know where the feeble gravitational force comes from.