Full Idea
The 'grain problem' for materialism was raised by Sellars: how could an experience be identical with a vast collection of physiological events, given the homogeneity of the former, and the fine-grainedness of the latter?
Clarification
'Homogeneity' is a smooth seamless quality
Gist of Idea
Why are minds homogeneous and brains fine-grained?
Source
David J.Chalmers (The Conscious Mind [1996], 3.8.5)
Book Reference
Chalmers,David J.: 'The Conscious Mind' [OUP 1997], p.306
A Reaction
An interesting question, but it doesn't sound like a huge problem, given the number of connections in the brain. If the brain were expanded (as Leibniz suggested), the 'grains' might start to appear. We can't propose a 'deceived homunculus' to solve it.