Reductionistic physicalism = The brain is in the brain.

Assume reductionistic physicalism: that all our thoughts, perceptions, emotions, volitions are nothing more than brain processes. Then all that we are conceiving of when we conceive of the brain are nothing more than brain processes. In other words, the brain is in the brain. But that brain must also be in another brain, and so on in a vicious infinite regress. This is just the problem of the homunculus turned inside out. Such is the philosophical “progress” of Daniel Dennett, who was so impressed by his teacher Gilbert Ryle’s “ghost in the machine” argument.