It happens very often that we put a great emphasis on what people think express verbally. I can see it in philosophical texts where, for example, philosophers deliberate what should be more important – expressed preferences or revealed preferences (see Decision Theory and Rationality by José Bermúdez, p. 64) or while listening to people who keep on talking about their beliefseven in absence of any decision making problem these beliefs could influence.
My take on it is that what ultimately matters is behavior and decisions. Description of human mental processes can help us understand some aspects of human behavior but is only a part of the picture. For example, if we want to see what a person truly wants, the action and the actual choice should be taken into account rather than what the person says she wants, even, or especially, when the two are in conflict. Similarly, it does not matter what convoluted theories people come up with in order to explain how their thoughts interact with their behavior. If their behavior can be fully explained by a simpler theory, then the convoluted ones should be discarded.
But why? Why am I so eager to demean human thoughts? The reason is simple. Verbal processing and speech are devices that serve some evolutionary purposes. I do not believe that providing a perfect window into the operation of the human mind is one of these purposes. On the contrary, we know that a lot of mental processes are unconscious. The part of the brain responsible for verbal processing is not connected to all other parts of the brain that are responsible for making decisions. Therefore, we are unable to describe fully what is going on in our heads. Furthermore, there aren’t even reasons to believe that spoken words are a perfect window into the part of mind that is available to verbal processing. It may well be a dirty window obstructing the view or a distorting mirror.
To give you an analogy – imagine that human nature is a picture of a ruined city with a single nice flower in the foreground. What people say about their thoughts can give you access only to the part of the picture that has the little flower, probably seen through a distorting lens. It is not wise to draw a conclusion about what the entire picture represents based on this little image only. If you want to know what the human nature truly is, you must go beyond the verbal processing and look at the entire picture.
The best way to think about it is to ask yourself a question: what could I learn about humans (and how) if they could not speak? Or even better: how would I go about learning about an alien species that I have no clue how to communicate with and who may be different to me in any aspect? If you can think about humans and analyze them as an alien species, then you are on a good way to be objective in your analysis of the human nature. But if you are focused on what people think that is going on in their heads – then you may be bound for a dead end.