Greg Detre
Thursday, 30 November, 2000
Mind VII, Snowdon
Our curiosity has focused on the problem of Mind since ancient Greek thought. The confusion has been expressed in many forms, revolving around the relation between the mind and body, physical and non-physical, or subjective and objective. The question can be turned on its head � �Are humans (merely) machines?� Seen in this light, the fields of physics, physiology and computer science are key. Indeed, technological progress has provided a succession of new paradigms through which to try to see our brain-minds, and new mechanisms with which to try and create artificial minds.
Certainly, our knowledge of the workings of the brain has deepened, both at the neuronal level and at the macroscopic systems level (benefiting from greater temporal and spatial resolution in neuroimaging). At the same time, our understanding of the physical laws of our universe has broadened, and become quite removed from anything we would characterise as common-sensical or intuitive, especially at the quantum level. Lastly, in computer science, AI and connectionist researchers have felt able to make strong claims about the feasibility of building a machine that can think � half a century later, and their credibility has suffered considerably. The ambitions of both fields have since narrowed, along with the complexity of the phenomena they seek to model.
There is a historical trend away from mysticism towards materialism. The mind remains as one of the very greatest mysteries,
One of the problems with talking about mind is that it is, by definition, subjective. We cannot access others� mental lives, except indirectly through language. Our attempts to categorise our inner world as words � broad, shifting categories, never sure whether the other person is describing the same feeling when he uses a word, only that he uses it in the same way (inverted spectrum hypothesis)
problem of other minds
We cannot directly convey the nature of our experiences to each other.
privileged access
subjective feelings
humans are the only intelligence we are aware of
�Can a submarine swim?�
The term, �machine� has often been used to describe something as contrasted with a being with free will, an automaton. I am going to try and avoid discussion about determinism in physical processes here, and simply define machines as being �constructed and containing no living tissue�. We will return to the implications of such a definition below.
Deciding exactly what we mean by �thinking� is harder. Certainly, thinking is mental activity; but in order to know how hard a hurdle we are setting for machines, we need to place �thinking� relative to the different standards of mentality that we seem to recognise. This is especially difficult because we need to remember that non-human forms of mentality will be very different to our own � we cannot simply disentangle the �human� from �human mind� on the basis of just our own case.
I am going to try and set out a series of assertions which characterise thought, in increasing order in the strength of their claims.
1. Thought is mental activity
2. A thought is always a thought-about-something. Usually, we give evidence of our thought by expressing it in language.
3. Thought is linguistic �
4. Thought always has a phenomenological aspect � there is always something it is like for the thinker to have a thought.
Require the machine to be performing and producing at a level comparable to humans???
mental activity
linguistic, process
spontaneous
considering, analysing, calculating, worrying, mulling over
free will
It seems important to first establish what we mean by �think�. Thinking is a form of mental activity. But can we have thinking without consciousness?
Surely, we don�t expect to be able to create a full-blown, human, phenomenological and linguistic consciousness, complete with our reflections, senses, insights, whimsy, emotions, personalities and neuroses? After all, human minds are the way they are because of the features and limitations of human bodies.
Nagel concludes that we can never know what it is like to be a bat for a bat � we can imagine, but only what it would be like for us to be a bat and to have a bat�s body.
but their neural wiring is different
can one brain-mind wholly encompass another?
But we need to be specific about what we require of a machine before we are prepared to say that it is thinking.
But what is �mind�? We know that we have minds. When pressed, we would probably agree that we are our minds, we are a res cogitans, a �thinking thing�. Certainly, when we die, our bodies remain, yet the mind seems somehow absent. Yet the mind cannot be severed from the body � what happens to the body, happens to the mind. In a similar way, we assume that we can build a machine such that it would have a mental life reflected by and dependent on its physical workings. But we are not prepared to be panpsychists � we shy away from ascribing mentality to everything physical, every flower, every rock and indeed every atom.
Although we hold thinking as almost synonymous with mentality, mentality is not an all-or-nothing concept. Indeed, it seems clear that mentality is a messy continuum.
It is a continuum in the sense that We can trace a path through the phylogenetic tree as far back as amoba, yet we have minds and they don�t (we don�t think). We would be reluctant to say that worms have minds really, but we would probably like to say that
continuum of intensity, also of quality/type/nature/senses/motor/processing/environment etc.
so the question becomes �how much can machines think?�, or �what sort of mental life can a machine have?�
Thinking is often used in the very broadest sense as a mental event. More often it refers to a process or succession of related mental events that are caused by other mental events, rather than a sensory perception of some kind.
There are a multitude of poor reasons for being quite sure that machines can�t think, without even having properly considered the question.
There is a (Christian) religious argument against thinking machines, which could run on many lines. In pre-Darwinian times, the Christian Church would have dismissed the possibility of thinking machines out of hand. Humans were regarded as divinely created and distinct from the animal �b� machines�, elevated by our souls, language and free will. The Church had to substantially revise its assertions after the theory of evolution became scientifically sacrosanct (although there are still parts of Bible belt America where the congregation are held in Genesis� thrall). Man and machine would now be considered divided by the divinely-instated mechanism of evolution. It remains to be seen whether the Church could credibly accept a machine consciousness into heaven. Any variation on this theme which holds humans to be without doubt the only intelligent life in the universe is equally unreasonable or would have to rely on some quasi-religious unscientific premise or leap of faith � it is remotely possible that humans are the only intelligent life in the universe, but there is no scientific reason to suppose that this is necessarily so. There is nothing special about humanity � we may be at the evolutionary pinnacle of our planet, but our view over the rest of the cosmos is sorely limited. The second main religious argument against intelligent machines is that it places us in a somewhat god-like role � by intimating that scientists can understand the workings of the highest orders of life, and even create new and �better� life, reduces the divine miracle of life. This is unnacceptable for the same reason that evolution was considered abhorrent � what is so god-like about God if we can forge souls ourselves? Those with a more literary turn of mind might choose to see parallels between AI and the apple in the garden of Eden -
There is a much wider category of people, branded carbon-chauvinists, who deem machines wholly incapable of thought because they are not biologically alive. By this, I mean that machines need not be carbon-based, or indeed contain any of the chemicals in our bodies and physiology is likely to be unrecognisably different. Furthermore, machines are artificial � we will have designed and built them. They would not exist �naturally�, i.e. had there not been other intelligent life to first create them.
� they are entirely separate from us and the entire animal and plant kingdoms.� Although they may replicate/reproduce, seek nutrition and even grow
Because they are artificial
In some senses, machines are not indigenous to Earth at all.
The fact that they aren�t human is an unreasonable one. Rationally, there is no reason to regard humanity�s mind and free will as anything but
god-given
carbon chauvinism
deterministic
processing power
Skinner � can we think
Minsky argues convincingly that it is unreasonable to claim that there is any basic difference between the minds of men and possible machines.
ethical quandary of conscious machines. it�s like animal rights, but even more alien and more chauvinist.