When Would We Know? — A Natural History of Consciousness: II. When Behaviour Became Evidence

We never observe another person's consciousness directly.

We observe what they do.

They speak.

They avoid injury.

They laugh.

They remember.

They become frightened.

They tell us what they are experiencing.

From these things, we infer that there is something it is like to be them.

Yet none of these observations, taken by itself, establishes experience.

A person could say “that hurts” without pain.

A person could withdraw a hand without feeling anything.

A person could describe an experience without having the experience they describe.

So why do we treat behaviour as evidence?

Because behaviour does not stand alone.

We interpret it as the activity of an organised system.

A human body does not merely produce words. It regulates itself, perceives its surroundings, remembers its history, anticipates consequences, changes its behaviour, and acts to preserve its continued existence.

The behaviour becomes evidence because it belongs to a particular kind of organisation.

And our own case gives us the starting point.

We know consciousness from the inside.

We then discover that other humans have bodies, nervous systems, developmental histories and patterns of behaviour sufficiently like our own.

The inference is not deductive.

But it is extraordinarily powerful.

Then the circle widens.

Other animals behave in ways that suggest perception, learning, preference, avoidance, exploration and increasingly complex forms of perspective.

The more the organisation resembles the kinds of organisation in which we already know experience occurs, the more behaviour can function as evidence for experience.

This matters for AI.

An artificial system might display increasingly sophisticated behaviour without sharing the organisation of a conscious organism.

Or it might eventually possess a very different organisation that nevertheless gives us reason to think experience is present.

In either case, behaviour would still matter.

But behaviour would be evidence within an account of organisation.

This is why the question cannot simply be:

“Does the machine behave as though it is conscious?”

We need another question alongside it:

“What kind of system is producing this behaviour?”

The first question concerns what the system does.

The second concerns what its doing might mean.

And perhaps this is where our difficulty begins.

We have become accustomed to treating consciousness as something revealed by behaviour.

But perhaps behaviour is evidence only because, underneath the behaviour, there is already an organisation whose activity makes experience intelligible.

If so, the history of consciousness-testing is not really a history of finding better questions to ask a system.

It is a history of learning what kinds of organisation make its answers matter.

And that leaves us with an awkward possibility.

Perhaps the decisive evidence for machine consciousness will not be found in something the machine says.

Perhaps it will be found in something the machine is.