Thinking and Computation - Thinking as Computation - page 3

One might also want to try to build machines that are capable of flight. There are two
ways to proceed:
study flying animals like birds, looking very carefully at their wings, their

feathers, their muscles, and then construct machines that emulate birds;

study aerodynamics—how air flows above and below an airfoil, and how this
provides lift—by using wind tunnels and varying the shapes of airfoils.

Both kinds of studies lead to insights, but of a different sort. The second strategy is the
more general one: it seeks to discover the principles of flight that apply to anything,
including birds.
It is this second strategy that is used here to study thinking. While there is a lot
to be learned by studying the brain, this topic focuses on the thinking process itself to
determine general principles that will apply to brains and to anything else that needs
to think.

1.1.1 What is thinking?

What exactly is thinking? For humans, it is clearly some sort of process that occurs in
our heads over time. The easiest way to understand it is to observe it in action.
Read the following sentence:

The trophy would not fit into the brown suitcase because it was too small.

Pause for a moment to make sure you understand it. Now answer this question: What
was too small? What does it refer to? Clearly, it refers to the suitcase, not the trophy.
Now, how did you get the right answer?
Observe that there is nothing in the sentence itself that gives away the answer. This
is easy to demonstrate. Simply replace the word small by big :

The trophy would not fit into the brown suitcase because it was too big.

What was too big? Now the answer goes the other way: it now refers to the trophy,
not the suitcase.
What this shows is that in making sense of the sentence, in particular, in determin-
ing what it refers to, you had to use what you already knew about the sizes of things,
things fitting inside other things, and so on, even if you were unaware of doing so.
This is thinking.
Thinking is bringing what you know to bear on what you are doing. This is what
you had to do to understand the sentence. The process happens in the brain, some-
times very quickly, and you may or may not be aware that it is taking place. (You may