Folk psychology is the derogatory term used by physicalists for our normal natural language (e.g., English, Spanish, etc.) way of describing mental states and explaining why people behave in certain ways.
E.g., she didn’t go to the concert on Saturday because she hates Taylor Swift.
Some materialists believe that those who believe in the existence of thoughts, beliefs, desires, motives and other mental states are victims of “folk psychology,” an unscientific attitude that will in due course be replaced by explanations in terms of the activities of nerves or brain states.
For those people, folk psychology is a kind of superstition, like belief in demons, and it will be left behind by the onward march of scientific understanding.
The alternative to folk psychology
The alternative to folk psychology is supposed to be scientific descriptions of the brain. Instead of talking about beliefs, we will describe brain states, or nerve firings. Instead of saying “Timmy likes Sally,” we will say “Timmy is in brain state G.”
There is no evidence of any kind that natural language descriptions of mental phenomena will be replaced by scientific descriptions of the activity of the brain. The claim that this will happen is complete science fiction at this point in time.
It does no good to complain that I am talking about beliefs and desires when there is no alternative at all to doing so. It would be like accusing me of being old-fashioned for driving to work instead of teleporting. Teleportation does not actually exist and may never exist. There is nothing scientific about contrasting reality with science fiction.
The materialist has written a giant unhonored I.O.U. and is treating the I.O.U. as though he has actually produced the cash and paid the debt.
Since what my brain is doing when I think of grandma may be quite different from what your brain is doing when you think about your own grandma (my grandma was a flesh-eating cannibal about whom I still have nightmares, while your grandma was the dictator of a small island country) it seems quite possible that individual knowledge about one person’s brain events would be necessary to give a scientific description, assuming such a thing ever proves to be possible. However, there is no science of individuals – just of classes of things. There is no science of Freddy the Frog – just of frogs. If specific details of the idiosyncratic goings on in individual brains is necessary, then in describing what someone is thinking, feeling or desiring, all the interlocutors (participants in the discussion) would need fantastically detailed knowledge about one person’s brain and all others referred to.
The notion of folk psychology as something replaceable with talk of brain states assumes that I will know what my brain states are. This suggests that I would need to have direct intuitive, first person access to physical goings-on in my brain. If this is not the case and my phone, for instance, is supposed to be constantly scanning my brain and giving me updates, presumably the resulting brain scan results would be so complicated only a specialist would be able to interpret and make sense of them anyway.
If the results were dumbed down sufficiently for the average person to understand them, then these results will presumably be more or less be identical to folk psychological terms and thus we would be back to where we started.