Reducing Folk Psychology
We can distinguish between two kinds of reductions in science. There are reductions where we do away with one side of the equation, and there are those where we keep both sides. We have done away with sunsets for scientific purposes. They are illusions due to elliptical orbits of celestial bodies. But that is different from reducing water to H2O. In the H2O reduction, water is no illusion. The water in our oceans is real.
Water was not eliminated as an illusion just because we discovered its chemical formula. Eliminative materialists think that water has been smoothly reduced to H2O. Discovering water molecules allowed for better understanding of water. The reduction is smooth because it makes scientific sense and because it fits with how water behaves. We may also make smooth reductions between theories. The Churchlands observe that the third gas law can be smoothly reduced to the laws of thermodynamics. If folk psychology is right—they claim—then it ought to reduce (intertheoretically and smoothly) to some materialist theory. But perhaps there is no adequate materialist theory of how the mind/brain works. In that case, the problem is not with folk psychology but with materialism.
However, the Churchlands suggest that an adequate materialist theory will be found—that folk psychology will fail smooth reduction and should be eliminated. In the past, folk psychology explained the natural and supernatural, but folk- psychological explanations of the natural world have been replaced with natural science explanations, and the supernatural world never existed. In other respects, folk psychology has not progressed since Aristotle. So folk psychology is not only stagnant but also degenerating.