This essay focuses on Hilary Putnam’s functionalism. Despite the title above, he actually took a position against the “materialism” and “reductionism” of machine-state functionalism. (A functionalist needn’t be a materialist or a reductionist.) Yet, as stated in my last essay, Putnam (1926–2016) is vitally important in the history of functionalism, at least as it applies to the human mind.
[This essay is a follow up to my ‘Putnam’s Immaterial Brains and Material Souls’.]
Much of Hilary Putnam’s functionalism is directed at — and a response to — materialism in the philosophy of mind. Putnam defined materialism (at least as applies to human persons) in the following way:
“[W]e are, as wholes, just material systems obeying physical laws.”
Putnam called that the “first thesis” of materialism. However, it’s the “second thesis” of “classical materialism” that’s the relevant one here. Namely:
“[O]ur mental states, e.g., thinking about next summer’s vacation, [are] identical [to] physical or chemical states.”
This is a controversial position. Indeed, many people are quite happy with materialism until it encroaches on the nature of our “mental states”. Putnam himself acknowledged the following:
“[A]re we just material beings, or are we ‘something more’? [] My purpose is not to dismiss the question, however, so much as to speak to the real concern which is behind the question. The real concern is, I believe, with the autonomy of our mental life. People are worried that we may be debunked, that our behaviour may be exposed as really explained by something mechanical. [ ] Mentality is a real and autonomous feature of our world.”
Putnam’s way of putting his position involves a neat and simple little identity. Many people may not have a serious problem with the simple statement that “our mental states are identical to physical or chemical states”. However, Putnam simply gave one example of a mental state: thinking about next summer’s vacation. So now we have the following:
Thinking about next summer’s vacation is identical to a physical or chemical state.
It’s here that things may seem counterintuitive, even for the materialist.
It must be stated that one can be a functionalist and a materialist at one and the same time. (Most functionalists in the philosophy of mind are materialists, or at least physicalists.) However, it’s still clear that Putnam, at least at this stage, was arguing against materialism as it’s applied to the mind and to human persons.
Turing States in the Philosophy of Mind
Interestingly enough, Putnam was reacting against his own previous functionalism when he wrote ‘Philosophy and Our Mental Life’. Or at least he was arguing against his own Turing-state position. He wrote:
“In previous papers, I have argued for the hypothesis that (1) a whole human being is a Turing machine, and (2) that psychological states of a human being are Turing states or disjunctions of Turing states.”
By 1975, Putnam wasn’t happy with this position. He went on to say that
“this point of view was essentially wrong, and that I was too much in the grip of the reductionist outlook”.
Some readers may be surprised to read that the machine-state position was classed as “reductionist”. They shouldn’t be. All sorts of positions can be classed that way. Thus, it isn’t just a matter of materialists reducing everything to matter, or physicists reducing everything to fundamental particles. The idealist Donald Hoffman, for example, reduces almost everything down to what he calls “conscious agents”. Spiritual thinkers reduce everything down to “universal consciousness”.
As for reducing “a whole human being” to a Turing machine, and psychological states to Turing states, this connects to a related idea of John Searle who argued that almost anything can have the numbers 0 and 1 assigned to it, and thus be deemed to be a (rudimentary) computer.
Putnam then tied all the above to the recent history (i.e., as it was in 1975) of the philosophy of mind. He wrote:
“The positive importance of machines was that it was in connection with machines, computing machines in particular, that the notion of functional organisation first appeared.”
This is a fascinating insight into the contingencies of the positions in the philosophy of mind. It all goes back to Leibniz and even further. We had Leibniz’s mill analogy of the human mind. Then we had the switchboard/telegraph analogy, with all sorts of other analogies too. The important thing here is to be aware of those philosophers and scientists who go beyond (mere) analogy, and who make statements such as, “The mind is a computing machine.”
Putnam on Multiple Realizability
Let’s now tackle Putnam’s case against the identity theory of mind.
His case strongly depended on the multiple realisability argument. Putnam put that argument in the following way:
“For it is clear from what we already know about computers etc., that whatever the program of the brain may be, it must be physically possible, though not necessarily feasible, to produce something with that same program but quite a different physical and chemical constitution.”
This passage is a product of its time, and yet it’s also forward looking.
For one, it assumes that the brain has a program, just as computers have programs. Of course, Putnam argued his case for this elsewhere. However, for now let’s simply accept it as it stands. And when we do accept it as it stands, it does follow that a program — which is an abstract object — can have quite different physical and chemical realisations. Programs in computers have a hardware made up of wires, cables, etc. That hardware obviously isn’t biological.
Simply, what matters is the program (or function), not the physical realisation of that program.
The conclusion here is almost obvious. Putnam wrote:
“Then to identify the state in question with its physical or chemical realization would be quite absurd, given that that realization is in a sense quite accidental, from the point of view of psychology, anyway (which is the relevant science).”
Let’s make that passage more concrete:
To identify the mental state of thinking about next summer’s vacation with its physical or chemical realisation would be quite absurd.
Yet it doesn’t seem logically impossible to go straight ahead and make such an identification. That said, it does seem to be counterintuitive.
The Deduction of Mental States From Physical States
Arguments in favour of functionalism, and correspondingly sometimes against materialism (or physicalism), take the form of denying the possibility of deductions to higher level states from lower-level physical bases.
Firstly, Putnam put the deductive position:
“[T]he argument is that if it is made of matter (and we make a lot of assumptions), then there should be a deduction of its behaviour from its material structure.”
There’s something very particular about Putnam’s take on such a deduction. He continued: “What makes you call this deduction an explanation?”
Putnam’s words make it seem that there could be such a deduction. Yet it still wouldn’t be an explanation. This raises the question as what Putnam meant by “explanation”, and why he saw it as being important.
According to Putnam, materialists believe that “the explanation must be at the level of the ultimate constituents”. Putnam himself didn’t take that view. He argued that “the ultimate constituents don’t matter, that only the higher level structure matters”. One seemingly obvious riposte to Putnam is to ask why there must only be a single explanation of (in Putnam’s example) a peg and a square hole — or of any other physical thing. (Putnam himself put the word “the” in italics.) Why not many explanations from many different angles? Yet Putnam also seemed to believe in the explanation. And that explanation could only be found at higher level structures.
Materialists have indeed traditionally focussed on “ultimate constituents”. (At least some materialists and physicists have done so.) Perhaps doing so doesn’t provide us with any explanations. So, again, this will depend on what Putnam meant by the word “explanation”. It certainly isn’t immediately obvious why higher-level structures trump ultimate constituents when it comes to explanation.
It should be remembered here that what Putnam was talking about in this example was a peg and two differently-shaped holes. So it’s possible that it only applies to this example, or at least examples like it.
In any case, “in this explanation certain relevant structural features of the situation are brought out”. Let Putnam make this more concrete. He wrote:
“The geometrical features are brought out. It is *relevant* that a square one inch high is bigger than a circle one inch around. [ ] It is *relevant* that both the board and the peg are *rigid* under transportation.”
What isn’t relevant here is microstructure. And microstructure isn’t relevant when it comes to attempting to put a peg in a suitable hole. However, that depends on the context of explanation, and what is and isn’t relevant in any given situation. Moreover, does Putnam’s own example really pass over to the more general debates about functionalism vs materialism?
At least here, Putnam stuck to the same example of a peg and two holes, and concluded:
“The explanation at the higher level brings out the relevant geometrical relationships.”
However: “The lower level explanation conceals those laws.” (Some readers may wonder why Putnam refers to “laws” here.)
All this led to what Putnam really wanted to focus on: “mental functioning”. He put it this way:
“[G]iven that we consist of such and such particles, could someone have predicted that we would have this mental functioning?”
Of course not!
Has any materialist ever claimed otherwise?
A materialist can still claim particles, etc. are the basis of mental functioning M, or even that the two things are identical. However, he doesn’t need to ever claim that mental functioning M can be literally deduced from such and such particles.
There’s a strong and important conclusion that Putnam drew from all this. It’s that “we do have the kind of autonomy that we are looking for in the mental realm”. It isn’t clear how Putnam’s conclusion follows. In other words, simply because we can’t deduce a particular case of mental functioning from such and such particles, that doesn’t automatically mean that we have “autonomy” in the “mental realm”. Human persons aren’t free from being determined simply because they aren’t aware of what it is that’s determining them. In fact, determinists have often made this point.
