Can a machine be conscious?
If a machine has the right organisation, is anyone home?
I
Yes, in principle
Consciousness depends on the organisation of a system, not on what it is made of. A machine with the right organisation would be conscious.
- Best argument
- Imagine replacing your neurons one by one with silicon chips that perform exactly the same function. Your behaviour would not change at any step. Chalmers argues that your experience would not change either: it is implausible that it would fade gradually while you insisted nothing was different, or vanish at some arbitrary neuron. If so, a silicon brain with your organisation is conscious, and substrate independence is true.
- Strongest objection
- The thought experiment assumes that function is all that matters, which is the point in dispute. If consciousness depends on specific biological processes, like particular electrochemical dynamics, a chip that only reproduces input and output may leave it behind.
- The reply
- Defenders answer that the replacement chips can be made to reproduce any level of detail you like, including the electrochemistry, and at some point insisting on biology looks like prejudice in favour of carbon.
- Defended by
- David Chalmers, Daniel Dennett, Alan Turing, Hilary Putnam
II
No: computation is not enough
Running a program, however sophisticated, does not produce understanding or experience. Minds need the causal powers of biology, or something like them.
- Best argument
- John Searle's the Chinese room argument: a person following rules to manipulate Chinese symbols can produce perfect answers without understanding a word. Programs manipulate symbols by their shape alone; meaning and experience are not in the syntax. Searle calls his view biological naturalism: consciousness is caused by brains as digestion is caused by stomachs, and a simulation of digestion digests nothing.
- Strongest objection
- Critics reply that the person in the room is only one part of a larger system, and the system as a whole might understand. Searle never explains which biological powers matter or why silicon could not have them.
- The reply
- Searle answers that he can memorise all the rules and do the work in his head, so there is no larger system left over, and still he understands no Chinese.
- Defended by
- John Searle, Roger Penrose, Anil Seth
III
We cannot know
There may be a fact of the matter, but we have no reliable way to detect machine consciousness, and may never have one.
- Best argument
- Language models are trained on human writing, so they will produce human-sounding reports of inner life whether or not they have any. Behaviour, which is our usual evidence of other minds, has been decoupled from the processes that produce it in us. Until we have a validated theory of consciousness, any verdict is guesswork.
- Strongest objection
- Total agnosticism is not a usable policy. We must decide how to treat these systems now, so we need some way to weigh the evidence, imperfect as it is.
- The reply
- Agnostics agree, and propose precaution: take seriously indicators drawn from the leading scientific theories, and avoid creating systems whose moral status we cannot assess.
- Defended by
- Jonathan Birch, Eric Schwitzgebel
Where you stand
Will future AI systems be conscious?
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For the full background, variations and open questions, read the entry: Could a machine be conscious?.