Abstract
This chapter discusses reasons why we have no prospect of knowing whether or not matter thinks. It focuses on the mechanist hypothesis, its purported explanatory scope, and John Locke's commitment to it. The chapter then demonstrates God's immateriality and its implications for the possibility that God has given perception and thought to some material things. It addresses the notion of divine superaddition elaborated in letters to Stillingfleet and considers how thinking, extension, solidity, and motion are connected in case they do coexist in the same substance. The whole difference between Locke and his opponents on the epistemic possibility of thinking matter comes down to this. He maintains, and they deny, that we know the fixed nature of substances of various kinds, a constituent of a substance that determines the powers it necessarily has and those it necessarily lacks.