| In cognitive science, the idea that the mind is the same thing as the brain. While a great many cognitive scientists believe this idea, they are split into two main schools of thought within it: intertheoretic reductionism and eliminative reductionism.
Intertheoretic reductionism holds that so-called folk psychology (the way the majority of people use words such as belief, desire, expectation, and so on to explain others' actions) is a valid way of expressing the things that occur in the mind because it has a one-to-one correspondence with the physical processes occurring in the brain itself. Since it is possible to describe the same phenomena through brain talk (talk of neurons, synapses, and so on), say the intertheoretic reductionists, the folk psychological explanations can be seen as just another way of describing the same thing. And, of course, they have examples. For instance, they cite the case of the Hermissenda snail, which can be classically conditioned to retract its foot when exposed to light by repeatedly exposing the snail to turbulence at the same time as the light is introduced. In folk psychology terms, this phenomenon can be explained by saying the snail expects to feel turbulence and wants to avoid being hurt, so it retracts its foot. However, it can also be explained in another way. Because the Hermissenda's nervous system is so simple, scientists have been able to completely map it out. They have, therefore, been able to figure out what happens on a neural level when the snail is trained to retract its foot. So, there is a one-to-one correspondence.
Eliminative reductionism, on the other hand, holds that folk psychology is simply wrong and must be replaced if there is to be any hope for realistic description of the mind in everyday life. To support this point of view, eliminative reductionists cite a Freudian theory that says that a person tends to forget a good deal of what happens to them during traumatic events through an act of repression so that he/she will not have to face the emotional pain of the trauma. However, scientists have disproven this theory. They have found that the reason people often do not remember much of traumatic events is because their brains release a chemical that inhibits the formation of memory within that time. In other words, it is not done for any specific purpose; it just happens as a side effect of the chemical released during trauma. Furthermore, whereas Freud claimed that the memory still existed somewhere within the mind, this shows that it was never encoded at all.
Both of these schools of thought are extremely convincing, and it is difficult to impossible to find holes in either of their arguments. Therefore, the only really logical explanation is that they are both partly correct. In some cases, folk psychology explanations correspond exactly to events in the brain; and in some cases, they do not and should be discarded. So, the two points of view actually help correct each other and create a more realistic view of cognitive science. | 
