Re: Forward vs. Reverse Engineering

From: HARNAD Stevan (
Date: Tue Mar 05 1996 - 18:30:09 GMT

> From: Rowe Anna <>
> Date: Mon, 4 Mar 1996 16:28:36 GMT
> Please could you tell me again what reverse and
> forward engineering are, and also what the difference is
> between behaviour and cognition.

Behaviour: What a person (or animal or machine) DOES and CAN DO:
its observable actions

Cognition: The processes going on in the head, both conscious and
unconscious that cause behaviour. Cognitive psychology is the field that
tries to EXPLAIN behaviour, to explain HOW we can do what we can do.

Forward engineering is normal engineering. It builds devices that can do
certain useful things for us: bridges, furnaces, cars, planes. It is
forward, because WE build the devices (by applying the principles of
physics and previous engineering). We know HOW forward-engineered
devices work, because we designed and built them.

It's reverse engineering when the "devices" were already "designed" and
"built" by nature (by evolution) and we have to figure out how they
qork, how they can do what they can do. (A "device" is just a causal
system that can do something; in this sense, we too are devices.)

To reverse-engineer our behavioural capacity, we need a theory of
cognition: a theory of what structures and processes are capable of
generating our behaviour. To do this, we study behaviour and brain
function, and we build models that have some (eventually all) of our
behavioural capacity; models that can do what we can do. For if the
model can do it, than we know how it can be done.

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