According to Carruthers’ (2006) massive modularity (MM) thesis, the central systems of the mind are widely encapsulated and operate via heuristics and approximation techniques similar to those found in computer science. It follows from this, he claims, that widely encapsulated central systems are feasibly tractable. I argue that insofar as Carruthers uses this weakened definition of encapsulation, his thesis faces a dilemma: either is a misnomer (Prinz, 2006) and therefore unrecognisable as a version of MM, or it isn’t, and must put forward a convincing version of MM (Samuels, 2006). I claim that Carruthers’ commitment to this claim about central systems meets this challenge by adopting an understanding of central systems whose information-frugal and processing-frugal operations allow for feasible tractability. I conclude that the CWT provides a plausible and distinctive account of MM.