Re: Babbage/Menabrea: Analytical Engine

From: HARNAD Stevan (
Date: Mon Mar 19 2001 - 11:15:34 GMT

On Sat, 24 Feb 2001 wrote:

> Church appears to me to be saying that that without the formal
> method, the informal method cannot be obtained via this "effective" method.
> Have I missed the point?

I think what Church meant was the same as what Turing meant. There is
no informal "method," there is just an intuition (which is of course
"informal") on the part of mathematicians, about what it is that they
are doing when they "compute" something. This is what they call an
"effective procedure" (a means of attaining a certain end), and this
is what the formal notion of computation is meant to capture.

The Church/Turing Thesis is then that whatever mathematicians can do,
and whatever they mean by "computation" or "effective procedure" is
captured by the formal model of a Turing Machine (and its

> Human intervention was needed to be eliminated as it would improve accuracy
> of calculations and increase efficiency

I don't think that practical reason was the only reason. It certainly
isn't the only reason today: It is so as to isolate the mechanical,
mindless computation from any human contribution. It is to make sure
the computation is autonomous, and not parasitic in some way on what
the human does, thinks, judges.

> Reflection is what we feel we do when we do things like making choices or
> decisions. There is a feeling of doing more than just rule following
> because there is sometimes no way of telling why a particular choice was
> made, it is just put down to an instinct or feeling.

And that is exactly what the "analytical engine" was intended to

> I think that Conceptions of intelligence imply doing what intelligent
> systems can do and perhaps also knowing how intelligent systems do them.

Yes, and then the question becomes (and remains): If it is possible to
do something by mechanical, mindless computation, can that be the same
thing we are doing it when we are doing it mindfully? Is Cognition a
form of computation?

Stevan Harnad

This archive was generated by hypermail 2.1.4 : Tue Sep 24 2002 - 18:37:22 BST