I. To Point, or Aim
The word "intentionality" means to point, aim, or direct towards some target, goal, or end. A better English word for it might be "aboutness": when something is about something else. We could also call it "meaning". When something has a meaning, it points to a specific end or target.
To take a few examples:
- The word "dog" refers to, or points to, it's referent: actual dogs.
- An arrow literally points to whatever it's intended referent is, such as a specific direction on a road.
- A picture points to it's subject matter.
- A thought about Mt Everest points to it's referent: Mt Everest
II. Peculiar
There are some peculiar aspects of intentionality that make it a complicated relationship. The relationship between pointer and referent does not need to involve any spacial distance. A thought or diagram of a "Betelgeuse" does not matter how close or far it is to the actual referent. Also, one can entertain two contradictory thoughts about the same referent. For example, "I believe the morning star is shining", and "I believe the evening star is not shining." The morning star and evening star are the same referent, and yet it is possible to have two different and contradictory thoughts about it at once, if you are not aware that they are the same object.
In addition, thoughts, words, pictures and so on can be about things that don't even exist, such as Santa Claus, or perpetual motion machines.
So this relationship between pointer and referent is a bit more complicated than a simple physical relationship between two items, and presents some interesting puzzles for the materialist who wants to say that mind is just matter and nothing more than that.
III. Problems for materialism?
We can look at a few quick reasons to think that intentionality is not a physical property, at least at first glance. For one thing, how can there even be a physical relationship between a pointer and a thing that does not even exist, such as perpetual motion machines? How can there be a physical relationship between a pointer and every object of a certain class, such as a thought about "atoms" in general? The thought points to every atom in the universe that has ever existed or will ever exist, so how can this relationship possibly be physical?
Another reason to suspect the impossibility of a physical explanation of intentionality is to just look at several of our earlier examples:
- The word "dog" refers to, or points to, it's referent: actual dogs.
- An arrow literally points to whatever it's intended referent is, such as a specific direction on a road.
- A picture points to it's subject matter.
IV. But what about computers? Computers are material systems that represent things!
Computers are often offered as an example of a material system that refers to things all the time, and we are not tempted to be dualists with respect to computers.
But is that right? Take an abacus. On an abacus, the beads to the right represent the ones digits, the next column of beads represents the tens digits, and so on. But we assign this meaning to the beads. The beads don't actually mean anything. They are just collections of quarks and electrons, whose negative charges repel the electrons in the stick and keep the bead in its column. The bead doesn't refer or point to the number 1, or anything else.
Computers are different in degree but not in kind from an abacus. The computer's display is in English words, or numerals, which again are created and given that meaning by us. Without our application of meaning to it, the words and numbers on the screen are just meaningless electrons that have nothing to do with anything. Or think about what is happening inside the computer. Electricity is pulsing in on/off patterns, which mean 1 and 0, the language of computers. But just like with the abacus, we assign this meaning to the pulses of electricity. An "on" pulse of electricity doesn't mean 0, or 1, or 2, or hotdog, or anything else. It's just a group of electrons moving along a wire. We choose to apply a certain meaning to it, saying that a pulse of electrons means "1", and an absence of a pulse of electrons means "0."
V. Mind is different
But now think about the human mind. Your thoughts represent things. They point to a referent. So if materialism is true, then your thought about Mt Everest would consist of a certain configuration of electrons, neurons, dendrites, and so forth in your brain. Just physical particles and nothing more. But unlike a computer or an abacus, no one is assigning meaning to those particles. So how can meaningless particles point to something without any other mind applying meaning to them, as we do with computers?
If we want to say that some sub-process in the brain assigns meaning to our thoughts, then this just moves the problem back a step without solving it. If a sub process is responsible for assigning meaning to the electrons in our heads, then we have to explain how that sub process can assign meaning. This is often called a "homunculus." A little man inside your head is doing the processing, but to explain how he can think and assign meaning to things means we have to postulate yet another little man inside his head, and so on to infinity. This is of course an indication that that solution is not viable.
VI. The problem stated
So that is the basic problem of intentionality, and the problems that materialism has to overcome in order to try to explain it.