An Interview with Professor Hugh Mellor

Reproduced from Cogito Spring 1993 by permission of the Editor.

This interview is republished in
Key Philosophers in Conversation: the Cogito interviews
Edited by Andrew Pyle
London: Routledge, 1999, 101-113.

Cogito: I understand that you studied chemical engineering at Cambridge. What was it that converted you to the study of philosophy?

Mellor: I went to America to do graduate work in chemical engineering, and took a master's degree at the University of Minnesota. I had to take a subsidiary subject, and discovered that Minnesota had an excellent philosophy department, run by Herbert Feigl, who had been a member of the Vienna Circle and was a friend of Einstein and Popper. I took a course with him. That was what really led, in the end, to my becoming a philosopher.

Cogito: So you came back to Cambridge to pursue studies in philosophy?

Mellor: No, I came back to England to become a chemical engineer working for ICI. But I found I'd been bitten by the bug, and although I enjoyed myself at ICI, they weren't going to pay me to do philosophy, so I took a chance and came back as a research student to Cambridge.

Cogito: Do you think that your early training as an engineer has left any lasting influence on your philosophical work?

Mellor: Yes, I think so. An engineer, as opposed to a scientist, has to tackle situations as they are out in the world, not trimmed to test a theory; and the engineer's problem is always to find a language, a way of describing the situation, which is simple enough to yield a solution, but complex enough to be reasonably realistic. That seems to me much more like a philosophical problem than most of those that scientists face.

Cogito: I think of you as very much a Cambridge philosopher. Do you think that there is a recognisably 'Cambridge' style or tradition of philosophy? If so, could you characterise some of its main features?

Mellor: I think there are two traditions of Cambridge philosophy. One is what you might call an ordinary language tradition, associated with G. E. Moore and then later Wittgenstein. But there is also a more mathematically based, scientifically oriented tradition of philosophy which I got from Richard Braithwaite, but which goes back through Russell and Ramsey and Broad. I feel myself as belonging to this tradition. Its main characteristic is that, although it doesn't worship science, it tries to keep its philosophy informed by relevant facts about science.

Cogito: In this century, many of the major studies on probability have come out of Cambridge - Broad, Ramsey, Russell, Keynes, Jeffreys, Braithwaite, Hacking, and your own book, The Matter of Chance. Do you think that has anything to do with the way philosophy was done in Cambridge?

Mellor: I think it's a special case of what we were just talking about. To understand probability philosophically you do need a certain amount of mathematics, but that's not the most important thing. More important still is an understanding of how concepts of probability are used in the sciences, for example in the assessment of scientific hypotheses. Now in Cambridge serious statisticians were also concerned with the foundations of statistics - people like R. A. Fisher. I think it was their interaction with ex-mathematicians like Braithwaite which prompted much of the philosophical work on probability in Cambridge.

Cogito: You recently edited the Philosophical Papers of Frank Plumpton Ramsey, the brilliant Cambridge mathematician-philosopher who died so tragically young in 1930. What particular parts or aspects of Ramsey's work were you trying to bring to the attention of modern philosophers?

Mellor: Part of what I wanted to do was simply to keep some important works of Ramsey's, which modern philosophers were well aware of, in print, and in particular to make them available in paperback so that students could get their hands on them. But there were other parts of Ramsey's work which I didn't think had received enough attention, so I was trying to bring them to the attention of philosophers. In particular, I'm thinking of his work on the nature of universals. Another such work was his article 'Facts and Propositions'. This contains a theory of truth which modern philosophers are familiar with, but that's only a small part of it; and I think the rest hasn't had enough attention, in particular the parts that deal with how linguistic meaning depends upon how the mind thinks.

Cogito: If Ramsey had lived to the ripe old age of his friend Richard Braithwaite, how might this have affected the course of twentieth-century philosophy, in Cambridge in particular and in the wider academic community?

Mellor: I think it would have affected the course of twentieth century philosophy simply because Ramsey was so good, that he would have done a lot more good philosophy in a number of fields. In logic, for example, Ramsey would have done invaluable work on the discoveries of Gödel (made the year after Ramsey died). In Cambridge, I think Ramsey would have continued to influence Wittgenstein and the way Wittgenstein's work was received. I think he might have prevented Wittgenstein having such a mesmerising effect on his colleagues and being made a guru in a way that was not helpful either to Wittgenstein or to philosophy in general.

Cogito: One noteworthy feature of your own philosophy is that you don't seem particularly concerned with the philosophy of language. Apart from a commendable concern for clarity (keeping the tools sharp, as it were), questions of language and meaning seem to have no special interest for you. Do you think that the so-called 'linguistic turn' in modern philosophy has been a mistake?

Mellor: It's true that I'm not especially concerned with the philosophy of language, not because I don't think it's important but because I don't have anything special to contribute to it. I have done some work on indexicals like 'now' and 'I' because mistakes about their meaning have encouraged mistakes about time and the self; but not much else. What I do jib at, however, is the idea that metaphysics depends on the philosophy of language and needs to be based on semantics. I think the 'linguistic turn' in modern philosophy has greatly exaggerated the importance of language for philosophy. That has had a very bad effect, especially on metaphysics but also on the philosophy of mind, which has also needed to be rescued from its subservience to the philosophy of language.

Cogito: You clearly believe that there are substantial philosophical questions, since you spend considerable amounts of time and labour trying to answer them. How do you respond to the Wittgenstein claim that metaphysics is just a product of the misuse of language?

Mellor: My response to that is that it just isn't true, and you can see it isn't true by looking at real issues of metaphysics. It's true that you can unearth serious metaphysical assumptions hidden in our language, and it's important to do that. But the most important issues - for example in the metaphysics of time - do not arise just because language has been misused, and cannot be settled just by not misusing it. Whether time really flows, for example, is a serious question, which cannot be settled that way. Ordinary language presupposes that it does, but that can be shown to be a mistake. The metaphysical assumptions of ordinary language are no more infallible than the Pope is.

Cogito: Time is of course a subject on which you have done a lot of metaphysical work. In Real Time (1981) you revive an argument of another Cambridge philosopher, McTaggart, for the unreality of tenses, i.e. of our past-present-future distinctions. He thought he had proved the unreality of time itself; you argue for the weaker conclusion that time is real but tenses are not. What is the philosophical motivation for this argument? Do you share the 'Spinozist' view of Jack Smart that all real (i.e. objective) facts can and should be viewed sub specie aeternitatis?

Mellor: I have no prior motivation here: I just follow the argument. It's demonstrable that tenses are not real, but it doesn't follow from this that time is unreal. In particular, one can still draw all the fundamental distinctions between time and the dimensions of space. But this talk of 'viewing' facts from the standpoint of eternity is very misleading. It's just a metaphor for expressing facts in statements that are not indexical, i.e. which are true at all times and at all places, like the statement that an interview between the editor of Cogito and a certain philosopher takes place in Bristol on 8 August 1992. There's nothing problematic about knowing that non-indexical statement to be true. It can be known at any time: you don't have to be in eternity to know it - that's nonsense.
But stripped of this silly metaphor of 'viewing', there is still a real contrast between these non-indexical statements and indexical ones like 'I am now being interviewed', which are true only at some times. Now the idea that tense is real is the idea that there are facts corresponding to these statements, which are facts at some times and not at others. What McTaggart showed is that this makes no sense. It is reading out into the world a characteristic - admittedly an important one - of how we think and speak. We do think and speak in tensed terms, and one and the same tensed thought, such as 'I am now being interviewed', can be had by different people at different times. Sometimes the thought is true; sometimes it is false. But what makes it true isn't that there is then a correspondingly tensed fact, that I'm now being interviewed, which doesn't exist at other times. What makes it true is the tenseless fact that the thought is being had by someone while they are being interviewed. I believe that these tenseless facts are all the facts there are. But I don't have to believe in eternity to believe that.

Cogito: I remember a talk you gave on the BBC some years ago, in which you argued that Einstein's Special Theory of Relativity (STR) can be used to refute the metaphysical claim that only the present exists. Can you sketch the argument for us?

Mellor: The STR tells us something that is initially very surprising, namely that there isn't a simple fact of the matter about what is happening in remote parts of space at the present time, i.e. simultaneously with some given event on earth. Think of a star one hundred light years away, and ask, 'what is happening there now, i.e. at the same time as this interview?' The STR tells you that there is no fact of the matter about that to within two hundred years. Any event there which I could see during this interview is definitely past; and any event which could be reached by a signal emanating from here now is definitely future. But within the two hundred years between these events it's a purely conventional matter, depending on the choice of a so-called reference-frame, what events are simultaneous with this interview.
Now those who think that only the present exists think that what exists is not only what is here and now, but also what is simultaneous with that across the whole of space. But STR tells you that simultaneity with the here and now does not pick out a unique set of events across the whole of space. So if you accept STR and maintain that only the present exists, you really have to shrink what exists to what is going on now and here. You have to think that nothing exists outside your present spatial location as well as your temporal location. And that is really quite incredible.

Cogito: Or, I suppose, that what exists depends on some arbitrary convention of ours; and that also, I presume, you would regard as absurd?

Mellor: Yes, that's obviously absurd. You can't bring things into existence by deciding to adopt a different convention about, in effect, how fast we are moving through space.

Cogito: I suppose people are motivated to assert that only the present exists (or sometimes, that only the present and the past exist) by their objection to the notion that the future is in some sense 'already there', as real as the past and the present. Do you think that is just a confusion on their part?

Mellor: I don't think it's a confusion, though I do think it's a mistake. It's demonstrably wrong, but a very natural thing to think because people believe, quite rightly, that what happens in the future can be affected by what they will do. So, since they haven't yet decided what to do, they think that the future is open to be affected by what they decide. And that's perfectly true. Now it's quite natural to think that this requires the future not to be there yet, in order to leave open the possibility of affecting it. But the fact is that the future demonstrably is there, including our future decisions, and this is consistent with those decisions affecting other future events. But that isn't obvious to start with, which is why people think that our ability to affect what happens in the future shows that it isn't there yet.

Cogito: Real Time raises a number of interesting questions about the relation between metaphysics and physics. At one point (p. 120) you jestingly dismiss a sort of Aristotelian-style 'refutation' of the big bang theory. Elsewhere, however, you claim to refute time travel (an idea that some physicists take seriously) by philosophical argument, and chide philosophers for being too reluctant to challenge the physicists. Do you have a considered view on the role of metaphysical assumptions and arguments in physical theory?

Mellor: It's a mistake to think that there has to be a priority one way or the other, that either metaphysics must dictate to physics or vice versa. Physics does indeed show us things which contradict some metaphysical assumptions, as the example of STR shows; and then we must of course tailor our metaphysics to fit those results. But equally, there are perfectly good metaphysical arguments, like those of McTaggart against the reality of tenses, to which physics must accommodate itself. And on the whole, physics does accommodate itself to this. It's just that many physicists, when they start talking metaphysics, don't realise that there are other constraints beyond those of physics. So just as it's important to tell metaphysicians to take account of relevant physics, it's important to tell physicists to take account of the constraints of logic and metaphysics to which physics is subject.

Cogito: Another area in which the same sort of questions are going to occur is of course that of causality. In Real Time you defend a principle of local causal action. Now many physicists would say that that principle has been discredited by discoveries in quantum mechanics. How would you respond to such objections?

Mellor: Well, physicists also find the phenomenon of so-called 'non-locality' worrying, precisely because it raises questions about causation. To see what the problem is, we have to analyse causality. We have to decide what it is we are insisting on when we say that there is direct action at a spatial distance. I think the most important thing about causation is that it provides what the philosopher Douglas Gasking many years ago called 'recipes', ways of making things happen. Now everyone agrees that non-locality does not provide a way of making things happen: that is what the so-called 'no signalling theorems' show; and that is what prevents these phenomena contradicting what I mean by local causation.
What makes these non-locality phenomena interesting to philosophers is that they do have some of the features we associate with causation, but not those features that enable us to bring one thing about by doing another one. So they force us to concentrate and clarify what it is we are insisting on when we claim that something is causal. The sense in which some physicists say that there is causation across space is an attenuated sense that doesn't entail the most important application of causation, which is that of giving us ways of getting things done.

Cogito. So you think that our most fundamental notion of causation is the 'recipe' sense, and that one can still argue a priori that local action is a necessary condition for causation in this sense?

Mellor: Yes. Of course it doesn't matter how you use the word 'causation', so long as you don't equivocate. You mustn't use the word in a weaker sense, then switch back to a stronger one and argue that phenomena which are only causal in the weaker sense could be used to get messages to people and influence their behaviour across space-like intervals of spacetime. You can't do that and nobody thinks you can. I think we would avoid a lot of confusion if we stuck to the stronger sense of 'causation' in which it does have the 'recipe' connotation. If we did, there would be no dispute about these cases.

Cogito: Your inaugural lecture presented a resolution of the problem of induction. Can you summarise the line of argument? Can it be said to be a distinctively 'Cambridge' solution, building on the work of Ramsey, Broad, Russell and Braithwaite?

Mellor: The main idea is that induction, inferring that things that have repeatedly gone together in the past will go together in the future, is justified because it usually works. That of course is itself an inductive inference, because it says that inductive inferences will work in the future because they have worked in the past. The standard objection to this is that it begs the question, because it involves using the inductive principle to justify itself. My reply to that is to argue that knowledge-claims in general, not just inductive ones, are justified not if we can justify them, but if they have in fact been arrived at by some process which makes them very likely to be true. That's what matters, and all that matters. In particular, we don't have to know what makes our claim very likely to be true.
Now I argue for this in a general way, and then apply this argument to the special case of induction. I show that the inductive justification of induction really does not beg the question. Because all that's necessary for induction to be justified is that as a matter of fact it usually works! We needn't be able to prove that it usually works. That's the gist of my inaugural lecture. It's true that I derived it from earlier work by Ramsey, Russell and Braithwaite, but inductive justifications of induction are not peculiar to Cambridge, although I suppose there has been something of a tradition of them in Cambridge.

Cogito: So the basic thrust of your argument turns on this epistemological point, that we can know something (or have good grounds for believing something) without having to know, or to justify, the means by which we came to hold the particular belief. In other words, in the jargon of the epistemologists, you reject the 'KK principle', the thesis that in order to know something I must know that I know it.

Mellor: That's right. That has always seemed to me an implausible principle, because it leads to an obvious regress which is not only obviously vicious but also incredible. If, in order to know something, I have to know that I know it, then in order to know that I know it, I have to know that I know that I know it, and so on, and I'd never be able to get started. It would take a very strong argument to persuade me that this KK principle was true, given that it would leave us knowing almost nothing. But there isn't a good argument for the KK principle, and there are good counter-examples to it which have nothing to do with induction. That was another part of my inaugural lecture. I argued in general against the KK principle, and then showed how rejecting it in the special case of induction enables us to solve the problem of induction.

Cogito: In the introduction to your recent collection of essays, Matters of Metaphysics, you say that the whole question of physicalism is as trivial as the doctrine is false. That might seem, out of context, to give comfort to some other 'ism'. Can you explain why it doesn't?

Mellor: Physicalism is normally opposed to dualism. The dualist says that there are two fundamentally different kinds of entity in the world, minds and physical objects, or two fundamentally distinct types of property, mental and physical. The physicalists accept this prima-facie distinction, but say that in reality there aren't any entities (or properties) of the purely mental kind - they are all reducible to entities (or properties) of the physical kind. What I reject is this basic division into two fundamentally distinct kinds of entity or property. There is a great plurality of properties - electrical, gravitational, chemical, biological, psychological - but there is no fundamental distinction of kind amongst them. There are lots of little distinctions, and interesting questions about which are reducible to which. So my view could be called a kind of 'trivial pluralism'. What I jib at is the importance physicalists and dualists attach to the distinction between the mind and its properties on the one side, and bodies and their properties on the other. They both think that you must either take this distinction to be absolute and fundamental, or take the mental to be somehow reducible to the physical. It is these shared assumptions that I reject.

Cogito: So you see no reason to believe either, on the one hand, the dogmatic assertion of the so-called 'unity of science', that everything must reduce to physics in the long run, or, on the other hand, the dualist's dogmatic rejection of reductionism. What you see instead are a lot of local issues about the reducibility of one particular bit of science to another?

Mellor: There are a lot of sciences, and whether they can all be reduced in some non-trivial sense to one basic science seems to me to be an open question and not a very fundamental one. I share the Kantian view that all the sciences are involved with phenomena, in a general sense, and these phenomena can be physical, chemical, biological, psychological, or whatever. They are all studied in ways that are methodologically similar, but of course they differ in detail according to their subject-matter. You can't investigate psychological phenomena with the instruments, using the same experimental techniques, which you need to investigate the stars. But that isn't a big issue. All sciences are part of the general project of finding out what kinds of phenomena there are, what laws govern them, and how they are interrelated: that is what unites the sciences. The division of science into different subjects studied by different techniques, and in differently labelled departments of universities, is merely a division of intellectual labour. It may be essential in practice, but it has no cognitive or conceptual significance at all.

Cogito: I understand that your next book is to be on the subject of causality. Can you give us some idea of the position you are going to be expounding and defending?

Mellor: There are different aspects to it, many of which I have taken from other people. For example, I take the common view that causation depends upon laws of nature. I believe, however, that causation also relates particular events, and that this is a local matter. In that sense I oppose a tradition on causation going back to Hume, which says that whether one thing causes another isn't a local matter: it just depends on whether things of these two kinds are correlated throughout the universe. I deny that, even though I think that one thing can only cause another if it is an instance of a law of nature. I also think that causality involves probability, so I have to say how I think they are related. Similarly with the idea, which I have again taken from others, that causal claims entail something about what would have happened if the cause had not occurred. All these elements have to be pulled together, and what makes me want to write a book about it is that I want to pull them together differently from my predecessors.
One main difference of my approach is the twist I give the idea I mentioned earlier, that causation is something that gives you recipes. If two things are related as cause to effect, then it always makes sense to bring about the cause in order to get the effect. Now this idea of being a means to an end is also studied in a completely different area of philosophy, namely decision theory. And, unlike most of my colleagues, I think that decision theory can be used to show how causation depends upon probability, via this means-end' or 'recipe' connotation. That is one fairly original part of my work.
Another idea, which is not original, but which I've emphasised more than most others, is the fundamental connection between causation and time: in particular, how causation makes time differ from the other dimensions of spacetime. The temporal structure of spacetime depends on causation, and the direction of time depends on the direction of causation. This is something else I want to bring out in the course of the book.

Cogito: You have recently been involved in two widely publicised debates, both of which have served to focus public attention on questions about what is and is not to count as legitimate academic work. The first of these two debates concerned parapsychology. What was your objection to promoting research in this field?

Mellor: Parapsychology trades on the familiar fact that there are lots of things about the mind that we don't know, just as there are lots of things about other aspects of the universe that we don't know. Normal science concerns itself with trying to remedy our ignorance in these respects. It tries to understand phenomena by discovering the laws governing them. Sometimes it succeeds and sometimes it fails. What's wrong with parapsychologists is that they count failure as a kind of success; that is, they think that failure to understand a phenomenon bestows a kind of glamour upon it, makes it something special, a paraphenomenon. It does nothing of the sort: all it means is that there's something we still don't understand.
The only way to keep this fundamentally silly approach going is by pointing to phenomena which look as if they should be explicable by normal science but so far are not. On the one hand, they must be phenomena that aren't obvious enough to cause serious scientists to change their theories to accommodate them. On the other hand, they have to be things which serious scientists have no interest in tackling in a normal way. The only phenomena that fit this bill are things for which there is very little evidence. That is, phenomena which only appear to show up in bizarre, unrepeatable, and anecdotal situations, rather like the Loch Ness Monster. But nothing follows from this. Any serious scientist will come across anomalous experimental results, things that don't work, things which suggest something that turns out in the end not to be there. To make a kind of occult mystery out of this commonplace, and out of our failure to explain everything we try to explain, is just not being intellectually serious. That's why, although I don't object to parapsychology as a spare time amusement for people with nothing better to do, I don't think a respectable academic institution should promote it.

Cogito: The second debate I had in mind was, of course, the controversy over whether to award an honorary degree to Jacques Derrida, the French philosopher (?) and littérateur. You were a prominent member of the opposition. You lost the vote, of course, but succeeded in making your point. What, though, is the precise nature of your objection to Derrida? Is it that what he says is false, or unintelligible? Or is it perhaps essentially a moral objection against a kind of intellectual irresponsibility?

Mellor: Some of Derrida's early work was interesting and serious. But this isn't the work he has become famous for, and which led to him being put forward for an honorary degree. That is much later work which seems to me wilfully obscure. If you spell out these later doctrines plainly, it becomes clear that most of them, if not false, are just trivial. Take the fact that the writing down of a signature must have been present at whatever time in the past it was done. Now you can make this truism sound mysterious, as Derrida does. But there's nothing mysterious about it: it's just trivially true that if an action leaves a trace, then the trace will always be of something in the past that was once present. So one objection is that Derrida goes in for mystery-mongering about trivial truisms. But he also mixes these truisms up with silly falsehoods, which, if believed and acted on, would cripple intellectual activities of all kinds. The excesses of deconstructionism have been especially unfortunate, because they imply that writings have no intrinsic meanings that are fixed or constrained in any way by the writers' intentions or the conventions of their language; that writings are open to endless and arbitrary reinterpretation by their readers. This is obviously false, and has the most absurd implications. In the law, for instance, it implies that because a statute has no intrinsic meaning it could be reinterpreted so as to sanction, or to forbid, any course of action whatsoever. That is nonsense, but if people really believed it, it would sanction all sorts of arbitrary and authoritarian practices by the state. So it is either just nonsense, if it's not believed; or it's very dangerous, if it is believed. I'm sure Derrida himself doesn't believe most of the nonsense he is famous for, but if you filter that out, the rest doesn't add up to anything worthy of an honorary degree.

Cogito: I can think of an example here that might appeal to a lover of the theatre such as yourself. In King Lear, when Cornwall has Gloucester's eyes put out, he is described as being 'naughty'. Presumably, a disciple of Derrida must believe that he is at perfect liberty to construe that word in its late twentieth century sense - the sort of rebuke that a mother would give to a child who had just stolen a biscuit.

Mellor: That's right. The fact that the word has changed its meaning since Shakespeare's time creates a serious problem for the actor who has to say that line. Somehow, the actor has to get the audience to take that word in something like its original sense. That is a serious activity which, if Derrida's doctrines were correct, would make no sense.

Cogito: One gets an impression of you, arising from these controversies, as a sort of embattled figure, struggling to defend Enlightenment values against a rising tide of unreason. Do you ever see yourself in that light?

Mellor: No, no. It's not a rising tide of unreason; it's just been a bad year for bullshit in Cambridge. But two episodes, however notable, are not statistically significant. There is a recurrent temptation, however, for academics who look too hard for excitement to find it in silly fashions. I think this generates a permanent running battle in some arts subjects between those who think straight about their subjects and those whom Mrs Thatcher described, all too accurately, as 'the chattering classes'.

Cogito: One of your passions is the theatre, and I believe that you still act. Is there any connection between that passion and your commitment to philosophy?

Mellor: Only that they are both things that I feel quite passionately about and want to pursue as long as I can. The only moral I would draw from this is that it's probably bad for people to treat philosophy as an all consuming vocation, to which they should devote their whole lives. I think it's healthy from time to time to get right away from a subject with the pretensions that philosophy rightly has. That makes you see and think about the world in a way that's fresh and independent of your philosophical ways of seeing and thinking. So the theatre is for me, perhaps, what backgammon was for Hume.

Updated 8 June 2004