Thinking and Computation - Thinking as Computation - page 11

This “trick” has turned out to be one of the major inventions of the twentieth cen-
tury, allowing devices that perform computation to permeate almost all areas of our
modern lives. And note: It has nothing to do with electronics or physics.
1.3 Thinking as computation
One might still ask, though, just what does computation have to do with ordinary
thinking? Recall the central conjecture of this topic:
Thinking can be usefully understood as a computational process.
What does this conjecture amount to?
Not that the brain is something like an electronic computer (which it is in some
ways perhaps, but in most ways is not).
The process of thinking can be usefully understood as a form of symbol processing
that can be carried out purely mechanically without having to know what the
symbols stand for.
Why is this so controversial? Perhaps the idea that some types of thinking are com-
putational is not so surprising. Consider activities like doing a homework problem
in algebra, or filling out an income tax form, or estimating a grocery bill as you are
shopping. These all involve thinking and are clearly computational.
The problem is that so much of our thinking seems to have very little to do with
calculations or anything even remotely numerical. You can think about anything you
want, not just numbers. Consider this example:
I know my keys are in my coat pocket or on the fridge.
That's where I always leave them.
I felt in my coat pocket, and there's nothing there.
So my keys must be on the fridge, and that's where I should look.
This is an example of thinking that appears to have nothing to do with numbers. But
it is about something: keys, coat pocket, refrigerator. In fact, thinking always seems to
be about something . Computation, on the other hand, seems to be about nothing :itis
the process of manipulating symbols in a mechanical way without taking into account
what the symbols stand for. So there is certainly a conceptual gap between the two
that needs to be bridged. Fortunately, the bulk of the groundwork was already done
by Leibniz.