A derivation of the Dirac equation in `3+1 dimensions is presented based on a master equation approach originally developed for the `1+1 problem by McKeon and Ord. The method of derivation presented here suggests a mechanism by which the work of Knut
h and Bahrenyi on causal sets may be extended to a derivation of the Dirac equation in the context of an inference problem.
The Feynman checkerboard problem is an interesting path integral approach to the Dirac equation in `1+1 dimensions. I compare two approaches reported in the literature and show how they may be reconciled. Some physical insights may be gleaned from this approach.
