The Part of the Mind Science Can't Reach

Last time we saw how, by adopting the empirical method to build a concrete methodology, modern psychology gradually left philosophy's great household — and made considerable strides in studying the human mind along the way. (Editor's note: the original article was titled "The Love-Hate Story of Psychology and Philosophy（Part Two）".)

The question is: given all that, do we still need philosophy to study the human mind? If the empirical method is this effective, haven't we simply outgrown the need for philosophy to study the mind at all?

In fact, contemporary philosophy still has a discipline called philosophy of mind. So the question we naturally have to ask is: why do we still need philosophy to study the mind?

What the empirical method studies must be a public world

Since modern psychology uses the empirical method to do its research, we have to take a close look at what makes the empirical method distinctive. What empiricism insists on is observation through experience — and, moreover, observation that different researchers can arrive at together. Take the biologists who study frogs: what they study is, of course, phenomena that everyone can observe in common（such as a frog's swimming motions）, and they then build theories together to interpret those phenomena（for example: why does a frog swim this way rather than that way?）. If there were a scientist claiming to be interpreting some frog-related phenomenon that only he could see, we would be entitled to doubt what exactly he was studying. And if he were the only person able to see this phenomenon, no other scientist could study it alongside him, and science could never get off the ground.

So the object of empirical research is necessarily public — something everyone can observe. Psychology is no different: what psychologists do is study those psychological phenomena that everyone might observe in common, and then build theories and offer interpretations to account for them.

The private side of the mind

And yet our everyday experience seems to suggest that the human mind is not entirely public. Part of it seems to be visible to ourselves alone — something no one else can observe together with us.

For example, try imagining the taste of fried chicken right now. Yes — that taste. Or try picturing the feeling of seeing something red. Yes — that sense of red. Have you ever wondered whether the taste other people experience when they eat fried chicken might be different from yours? Or whether the feeling other people have when they see red might actually be the feeling I have when I see green — only because everyone's entire colour spectrum happens to be inverted in the same way, we have never discovered that the sensation we each have of looking at the same colour is in fact not the same?

Push it one step further: has anyone ever wondered whether other people, when they eat something, have no "taste" at all of the kind you feel when you eat? Whether other people might in fact be like robots, sensing light with photoreceptors but having no sensation whatsoever of seeing colour?

It sounds quite preposterous, doesn't it. But think a little deeper: what evidence do we actually have to prove that other people have the sensation we have when we see colour, or that their sensation of seeing red is the same as ours?

The problem lies precisely here: each of us can only feel our own sensation of seeing colour, but can never feel anyone else's. So we seem to have no direct evidence with which to say whether another person's sensation of seeing red is the same as mine, or indeed whether they have any so-called sensation of seeing colour at all.

These sensations, on the face of it, seem to be something only we ourselves can feel, while others are bound never to — this may be called "the private region of the mind".

The study of the philosophy of mind

Because these regions appear, at first glance, to be felt by ourselves alone and by no one else, they simply cannot be studied with the empirical method. Different psychologists can each feel only their own sensation, but can never observe the very same sensation together. And that means the empirical method can no longer be used to study it.

Much of the research in contemporary philosophy of mind revolves precisely around these sensations that appear to be felt by ourselves alone. What are they? What relation do they have to our brain? What relation do they have to the physical world? Are they the same thing? Or is one the cause and the other the effect? Or is the relationship something more complicated still?

Because empirical psychology needs to observe public phenomena in order to study them, empirical psychology simply cannot study the questions above. And here a space opens up for philosophical inquiry: what, in the end, are these apparently private things really made of?

One thing to keep in mind, though, is that it is not the case that every philosophical theory holds this private region truly to exist. Some philosophical theories hold that there are no such things at all. At the same time, it is not the case that every philosophical theory holds this region to be genuinely private; some theories hold that this region is in fact public after all. But whatever their reasons, the empirical method is still not enough to reach such a conclusion. We still have only the methods of philosophy with which to argue why these things in fact do not exist, or why they are only privately so on the surface while in fact still being public. And so, when it comes to questions of the mind, philosophy still has a place.

Author: Yim Chun-bong @ Corrupt the Youth – Philosophy Section. Republished with permission; original article here