If we translate this talk of computers into talk of the mind, we can see that the Functionalist views mental states as functional states of the brain. We may compare the brain with other organs, such as the eye. The individual parts that make up the eye all serve the function of seeing. In a similar way, the parts that make up the brain all serve the function of thinking. Yet, in neither case - the Functionalist argues - would we want to say that the description of physical states is sufficient to understand what is going on. For instance, the parts of the eye allow us to see, but the individual state of each part is not what we mean by "seeing".

In this way, Functionalism draws a distinction between a particular state or property being dependent upon something and something being that thing. So, in terms of the brain, mental states are dependent upon brain states or neurological activities in the same way that the functions of a computer program are dependent upon computer hardware. The way Functionalists speak about this is to say that brain states help to realise mental states and that the mind is in fact a total functional system. By this they mean that a mind is made up of the total possible functional (mental) states that it can have and that these interact with the “inputs” and each other in order to produce “outputs” or behaviour. For instance, take the example of trying something new to eat (based on example given in Heil, chapter on Functionalism - see Further Reading):