A conversation with the Rutgers University philosopher.

Question: Why do you think it's valuable to link the study of philosophy to the study of physics?

Tim Maudlin: Well, I think if you think about the history of philosophy, you would have a hard time making a distinction between the two.  If you go back, Aristotle has book called "The Physics." In fact one of the reasons we call a big chunk of philosophy metaphysics is it was the sort of stuff Aristotle thought you should study after studying physics.  

Plato has an account of the physical world, Descartes, obviously did a lot of physics, Liebnitz did a lot of physics.  So it’s more the question, "How did they come apart?" than "Why you should put them together?"

And part of the reason they came apart is that the physicists got too good at what they were doing and too specialized.  I mean, they became... mathematical physics became such a power independent tool that you had to devote yourself to it and probably had less time for doing what we would recognize as general metaphysics, general philosophy, talking about how you arrive at the conclusions that you arrive at, what the evidence is, what is really the nature of the physical world is, that lies behind the equations that you are using and things like that.  

So I think of philosophers who are interested in physics as addressing the traditional philosophical question, if you will, what exists in the particular case of the physical world because you can ask about mathematics, what kind of existence mathematical objects have?  For example, you can worry about the mind/body problem and you can worry about the kind of existence minds have, which tends not to come up so much in physics.  But just the issue of the nature of space and time, the nature of matter, the nature of physical law.  All of these are recognizably philosophical questions that obviously depend upon understanding physics.

Question: What do physics and philosophy contribute to each other?

Tim Maudlin: I guess the physics – the way things are set up now, physics provides you with a mathematical formalism that has been tested in various ways and seems to be extremely powerful at allowing you to make certain kinds of predictions.  But the mathematical formalism is not self-interpreting.  You can study the mathematics as mathematics in great detail and still not be at all sure what in the physical world is represented by this mathematics, even questions like, which parts of the mathematics represent anything in the physical world, and which parts are just artifacts of having set up the system in a certain way.  

And those kinds of questions are more in the province, I think of philosophers or people trained in philosophy.  They’re sort of conceptual questions, questions about evidence, questions about how you sort out, in any kind of representation of the world, which part corresponds to the world in a certain way and which part doesn’t.  

So there’s kind of that division of labor, but it’s very artificial to suggest, quite honestly, that there is a strong division.  As it turns out, there’s a general unified community doing foundations of physics, worried about the fundamental conceptual problems rather than worrying about running particular experiments or calculating constants to more degrees of accuracy or doing engineering and lots of interesting things you can do.  

But if you ask the very basic conceptual questions, what we call foundations of physics, there’s a community.  And that community is about equally divided between physicists, mathematicians, or mathematical physicists and philosophers and the people live in these different departments in universities, but any of the meetings will have all of them together, all of them talking about the same issues from slightly different angles, maybe, but able to communicate usually quite effectively.  

Question: What other disciplines in science could benefit from a philosophical perspective?

Tim Maudlin: We are just beginning to tackle questions in cosmology; I’ll just give you one example because I happen to be thinking about it recently.  And cosmology is, on the one hand, kind of the application of physics, but on the other hand involves particular problems about thinking of the universe as a whole and what it would mean to explain the universe as a whole.  Those are obviously philosophical questions.  You can go back to Cont worrying a lot about what it would mean, or what could it mean to have an explanation of the totality of the universe rather than an explanation of one piece of the universe given in terms of another piece.  So, there are particular conceptual problems that come up in that context that are, I think, people are only beginning to look at.

More recent new sciences are probably too young yet to have clearing of content for a lot of philosophical input.  I mean, you need to have a fairly stable discipline up and running with some very stable principles before, as a philosopher, you go in and have the subject matter you need to try and analyze.  

Question: What can applying philosophy to the physical world reveal to us about the nature of reality?

Tim Maudlin: Let me give you a very concrete example.  When you learn chemistry, or physics in high school or in college, you learn that there are electron shells that in a hydrogen atom, for example, there are various orbitals that an electron can be in, and you explain a lot about how the hydrogen works by talking about the electron jumping between different shells and giving off light or absorbing light, depending upon what these jumps are.  And in the books, you’ll see a picture of the shape of these different shells, whether it be an “S” shell that looks like kind of a fuzzy sphere that surrounds the nucleus and these other “P” orbitals, and “D” orbitals that have funny-looking shapes.  

Now, one very clear question to ask is, what is that a picture of?  You open the book and you see this funny shaped object.  Is that – does that mean that an electron at a particular moment in a hydrogen atom forms a kind of spherical shell around the nucleus, or does it mean the electron is somehow moving and what you have is a kind of long exposure picture where you’ve allowed – you’ve watched the orbital motion go on for awhile and you see, oh its tracing out a sphere.  Or does it mean that, as often people would say, the electron is sort of popping in and out of existence somehow.  It often doesn’t have any location, but sometimes it sort of shows up, and again, we have a long time exposure and the places it shows up it forms this kind of a shell.  

Now that’s a physical question.  It’s asking, what really is an electron, in this case, how does it inhabit space and time?  And you’d think that should be a question that a physicist as a physicist would want to answer in order to understand what their theory is telling them about the world.  It’s not a particularly philosophical question, but we’ve gotten to a situation where most physicists would not recognize it as a physical question and would not attempt to answer it and would some how think it was improper for them as physicists to attempt to answer it, or would say it is somehow a meaningless question or something like that.  And we arrived at that situation through a sequence of philosophical positions, which no longer anyone thinks are tenable and a sort of crisis in physics where you had a mathematical formalism that worked very well and nobody knew quite what to make of it.  And physicists made a fairly self-conscious decision to dissuade their students from thinking about it because they thought that was just going to confuse them and get in their way and prevent them from doing the important physics which involved doing more mathematical calculations and figuring out how to build explosive devices, and so on, which you can do perfectly well without having answers to these questions.  

So, insofar as you’re interested in physics as a tool for engineering, you can pretty well ignore all of these questions, but I would think, would hope that most students of physics don’t go into physics in order to become engineers.  They go in initially motivated by a simple curiosity about the world and what they’re hoping is that they’ll find out about the world the way if you’re interested in how biological creatures manage to reproduce and you finally understand how DNA works and how the strands separate and how they replicate.  You say, “Oh there was a real puzzle about how all this works and now I understand it.”  That physics should be like that.  There is a real puzzle about how atoms work and find the four molecules and what’s going on.  And you would turn to physics to answer those questions.  

As I say, the peculiar thing, I think the historical peculiar and conceptually peculiar is that physics as a discipline has tended to turn away from those questions and to some extent now is turning back to them. 

Question: What is experimental philosophy, and how is it different from conventional philosophy?

Tim Maudlin: Now, the stereotypical philosopher sitting in an armchair actually can be doing experiments, but only on one subject, mainly himself, or herself.  Right?  So you can say, “Ah, how does the human mind work? I’ll just reason about things and I’ll introspect and I’ll figure out what I’m doing and I’ll write that down and say, this is how the human mind works.”  Now, anybody thinking about it for a few minutes would think, well wouldn’t it be better to actually go and check other people as well?  Maybe you’re an odd case.  Maybe you don’t have such great insight just by introspection to figure out what the process of the thinking you are going through.  Wouldn’t you do better to examine a lot of people and to ask sort of more – in a more detailed and systematic way in an experimental setting to kind of tease out the way people think?  

Well, certain people doing that sit in cognitive science departments and certain people doing the very same thing sit in philosophy departments.  And what’s the difference?  Maybe there’s a slight difference in focus as some people doing philosophy foundations of physics sit physics departments and some people doing foundations of physics sit in philosophy departments.  And the difference is, the people in the physics departments will certainly, probably be doing more calculation, be more worried about solving particular problems, will have more technical things and the philosophers will have more leeway to spend time asking more general questions, more conceptual questions.  But in a way, the project is one project.  

So there’s some part of experimental philosophy which is simply observing that traditional philosophical questions are about the way the world works and the best way to find out about the way the world works is to observe it in well defined experimental situations.  And so you just raise the bar in terms of what you are doing.  

From that point of view, it’s not anything terribly astonishing and not anything that changes the nature of philosophy.  It just makes certain bits of philosophy a bit better.  Now some people may complain, and it may be correct, I am not myself an expert in cognitive science, that the philosophers interested in doing this, is just not very good cognitive scientists or they’re not very sophisticated in how they set up their experiments, I don’t know.  But in principle, there’s no reason why certain questions that arise you might want to do experiments to figure out.  

What I’ve been arguing all along is philosophy, at least certain parts of it, are simply interested in finding out how the world is.  Usually described at a very general, generic level, right?  We’re not that interested in the exact population of Lithuania.  That’s a fact about the way the world is, but you’d say not a philosophically interesting one.  But what’s the difference between asking that and asking about the fundamental nature of space and time?  

Well, space and time is a much more sort of general, pervasive thing, but you’re still asking a fact about the world.  That is the kind of fact that a scientist would be interested in.  If you’re asking about the nature of the human mind, which any philosopher over the history of time would do, you are asking about something about the world.  There are minds in the world; they work some way or other.  

So the questions... there’s never been in this area, a distinction between a scientific and a philosophical question.  There is a distinction between more empirical method and more as it were, conceptual analysis.  A method that’s a bit further away from experimentation.  But that’s a matter of degree.  And so if these questions that you ask at a more general level can be brought down to an empirical test, then you ought to go and do the empirical test.  And then you’ve got to learn the techniques of good empirical tests, that is, the techniques of properly conducted science.  

Question: How can philosophers help us to understand quantum mechanics?

Tim Maudlin: How should anybody think about quantum mechanics? Quantum mechanics is a perfect example.  So you have Richard Fineman famously saying he can safely say nobody understands quantum mechanics.  Right?  One of the greatest physicists of the 20th century who’s main work was in quantum mechanics claiming he didn’t understand it.  He says he himself does not really understand the picture of the world that quantum mechanics is presenting us with.  I would think a physicist, as I say, as a physicist should find that frustrating and upsetting and a failure of physics that this fundamental mathematical theory they’re using they find they don’t really even have in themselves the sense they understand what it’s telling you about the world.  

It’s just that if you’re a philosopher, you have the luxury of spending all of your time with that worry of beating your head against it.  As a matter of fact, it’s a hard question and it requires people thinking very carefully and very deeply and furthermore, coming up with detailed physical theories, detailed physical accounts to try to understand quantum mechanics.  And that foundational work tends not to have immediate payoff practically.  It doesn’t mean that the predictions of the theory when you make sense of quantum mechanics will change or will change much.  Sometimes they even change a little.  Sometimes people trying to understand quantum mechanics will propose a way of understanding it that actually means the very predictions it makes will be altered a tiny bit, often such a tiny bit that you can’t even check it in the lab.  

But there’s not that much practical payoff, and insofar as you are a physicist who care about practical payoff or you’re embedded in a larger enterprise that cares about practical payoff, then you’re going to regard these questions as not of immediate interest.  Right?  They’re not going to repay you thinking about them.  And the luxury that philosophers have is that as we’re paid to think about things that don’t pay to think about.  And so we can spend our time worried about these foundational issues and not feeling guilty about them.

Question: What is the payoff that you get from this kind of inquiry?

Tim Maudlin: Well there are two things you would like to do.  Ultimately you would like to settle on a clear physical account of the world.  Like, what’s going on, like I say, go back to my electron.  What’s really going on with that electron?  The aim you have is to answer that question.  Now as it turns out, if you look at the precisely defined interpretations of quantum mechanics that exist today; and by precisely defined, I mean the ones where you have a clear mathematical account of what’s going on, in terms that are not vague and ambiguous.  For example, if someone in the standard theory you say, “Oh, a system will develop in a certain way until you measure something on it.  And when you measure something, then things go very differently.”  And as John Bell pointed out, that’s just unacceptable vagueness because, what does it mean to measure something?  You know, you’re saying in on circumstance it does one thing in another circumstance it does another very different thing, but the difference between those two circumstances it not well defined.  

So the first ting you want to do is have a clear theory.  A theory that tells you clearly what exists, tells you clearly what it does, and that you see, well given that, I can understand the world around me.  As it turns out, there are various ways to do this; quite different ways to do it.  Ways that give you very, very different pictures of what’s going on in the world in a microscopic scale.  

What you’d like to then do is choose among them.  Now, you may not be able to do it.  How do you choose among them?  Ultimately you’d like to do it empirically.  You’d like to say, well there’s some experiment I’d like to run to decide between these.  But in certain cases, it’s sort of provable that no experiment can decide between them.  Or you might hope that one of these pictures and not another, one of these models and not another can be extended to cover gravity or can be extended to cover some new phenomenon.  And then that would give you a reason to prefer one.  

It may turn out that at the end of the day, we will never know.  It may turn out that the world has not been made and our brains have not been made and our access to the world through our senses has not been made to allow us to discover all of the facts about it.  And then you’d be depressed a little bit.  Those are the breaks, right.  

Question: Where do cognitive science and philosophy interact?

Tim Maudlin: The question, "By what principles do we reason?" has been in philosophy forever.  One of the thoughts about logic is that logic is the theory of how we think, how we infer, how we get from some set of predeces to some conclusion.  Now actual human behavior turns out not to be very good valid, logical thinking.  I mean, there are lots of choices where there are sort of cognitive illusions, or you can show that people don’t think demonstrably in a way that makes a lot of sense.  For example, Kottman and Tversky famously gave these examples.  You’re going into a store to buy to items.  One costs $100 the other costs $15 and you find out that across town, the $100 item is on sale for $95.  Do you bother to go across town to buy it?  And people say, “Naw, probably not.”  You go into a store, you’re going to buy an item for $100 and another one for $15, you find out the $15 item is on sale across town for $10, do you bother to go across town to buy it?  And they’re much more likely to say, yes.  Even though in each case they’re paying the same amount of money for the same two items, but in your mind you think, “Oh, it’s a big sale!” on the $15 item.  I mean, that’s a third off.  And the sale on the $100 item, $5 off, that’s really, you know, that’s just change.  You know, round it up it doesn’t matter.  So the actual process of coming to a decision there is demonstrably irrational.  

There’s an interesting question that anybody would have is, well what’s the mind doing?  I mean, I gave a little sketch, a kind of obvious looking sketch of the way it’s thinking and you can sort of see it’s thinking isn’t really coherent, or doesn’t work well.  So again, insofar as philosophers have been – anybody’s been interested in how the mind works, and philosophers have been interested in that forever, they would be interested in cognitive science because it’s just a more systematized way of asking those questions and subjecting them, hopefully to experimental tests to check the answers properly.  

It’s changed philosophy of mind in a simple way that as cognitive science discovers things about the way the mind works that anybody doing philosophy of mind has to take account of that.  If they’re trying to give an account of the human mind, you have to take account of what’s been discovered about the human mind.  And if you’ve been thinking about the structure of the human mind, you might come up with questions that you’d like the cognitive scientist to look into.  That maybe they hadn’t thought of.  You might, as a philosopher again, thinking in a more general way about how the mind is organized, say “How could I tell – How could I decide between this account of the organization of the mind and that account?”  Well, here’s a situation where, if it’s organized this way you’d expect people to behave this way and if it’s organized the other way you’d expect them to behave the other way.  And then you have to go to your colleagues on the experimental side and ask them, would you please run an experiment and see which way it goes.  

Now the particular details, well, there’s obviously a sense in which, for example, nowadays; there’s a lot of interest in emotion.  There was a focus on, as it were, pure cold, calculative reasoning because you can give a cleaner looking, formal account of that, but as soon as you start looking at how people actually reason, you find that they’re systematically affected by their emotional state.  And I would say that the demonstration of that forces philosophers of mind to think much more clearly about to what extent emotion and affect play a role in our cognitive economy, and probably it’s easier to ignore that question if there aren’t a lot of cognitive scientists running experiments and pointing out that, in fact, emotions play a bit role in how we think.  

Question: How is philosophy valuable in our daily lives?

Tim Maudlin: Well if you ask me about what philosophy is, to be engrained, like what – there are detailed philosophical theses of various sorts.  And in day-to-day life, it’s probably not all that – it’s not going to be all that affected by choice among some of these.  If you think of philosophy, and I think this is a bit better and more important.  If you think of the job of the philosopher methodologically is to very carefully figure out by what reasoning you arrived at some conclusion, or why is it you hold some belief.  What are the grounds for it?  How did you get to it and are those grounds good grounds for holding it?  To carefully review arguments and unearth their presuppositions and then hold those presuppositions up to the light of day and ask whether you want to believe them.  That’s what I would say is the foundation of philosophical method.  

And this sort of thing that even say in philosophy of physics, physicists are not likely to do.  They’re not likely to take the foundational principles that they’re using and hold them up to the light of day and ask them whether they should believe in them.  They’re more likely to say, well this is just the principles we work with, accept them, use them, and don’t ask about them.  That’s ore or less the story any undergraduate would get about quantum mechanics as they say, “Shut up and calculate.  Don’t ask me why these are the rules.  Just follow them.”  

I think in everybody’s every day life, that habit of mind would make a tremendous difference.  I think the amount of belief that people hold for no good reason is distressing.  And that the level of argumentation in our political life is abysmal.  And the room for improvement, of clarity of thought of clarity of expression is almost unlimited.  And if philosophy could help the world, it would be much more – instead of by having people adopt some philosophical doctrine about this or that, it would be to bring them a bit closer to the care and precision of thought that is characteristic, I think particularly characteristic of philosophical work. 

Recorded September 17, 2010

Interviewed by David Hirschman