The relationship between determinism and free will is still vigorously debated. However, despite the activity one contribution from around 70 years ago has been largely ignored. In the 1950’s Donald M. Mackay presented a position he called Logical Indeterminism. At the time it was the subject of intense scrutiny, but no real interest has been shown in it since his death in 1987. In this paper I situate his work within the current debate, identify a flaw in the original argument and present a modal version that removes the flaw. The aims of the paper are twofold: to present a robust argument for the compatibility of determinism and (libertarian) free will, and stimulate interest in the work and contributions of Donald M. MacKay.
