Concept empiricism and the vehicles of thought

Concept empiricists are committed to the claim that the vehicles of thought are re-activated perceptual representations. Evidence for empiricism comes from a range of neuroscientific studies showing that perceptual regions of the brain are employed during cognitive tasks such as categorization and inference. I examine the extant neuroscientific evidence and argue that it falls short of establishing this core empiricist claim. During conceptual tasks, the causal structure of the brain produces widespread activity in both perceptual and non-perceptual systems. I lay out several conditions on what is required for a neural state to be a realizer of the functional role played by concepts, and argue that no subset of this activity can be singled out as the unique neural vehicle of conceptual thought. Finally, I suggest that, while the strongest form of empiricism is probably false, the evidence is consistent with several weaker forms of empiricism.