Barry C Smith is a Director of the Institute of Philosophy at the Institute of Advanced Studies at University of London. His interests range from the philosophy of wine to Chomskyan theory of mind and language.

He co-edited The Oxford Handbook of Philosophy of Language (2006) with Ernest Lepore. Following his 2007 collection, Questions of Taste - the philosophy of wine (Oxford University Press), he began working with psychologists, neurologists and neuroscientists on flavour perception and is now the co-organiser of an international research project on the Nature of Taste.

So the topic up for discussion is binaries in nature and whether or not they’re real or fictitious and created by us. But I suppose the first question is what do we mean when we talk about binaries, opposites? And is there any sense in which binaries are distinct from “x and not x”?

Well, I think we all know what we mean by binaries. I think that’s pretty clear. What we are interested in is whether these binary distinctions we make – male/female, child/adult, present/past – are created by us or by nature or just by the way the world is made.

So the ones that I think we can rely on are, for example, acids and alkalines. We can rely on carbon and non-carbon atoms. We can talk about positive and negative charges of particles. These are things which are not up to us to behave in the way they do.

True and false is interesting, and I think, although we think of true and false as binary oppositions, they're not the only oppositions in that ballpark, because when we talk about true and false we can also talk about not true. Not true is not automatically the same as false. When you say that a statement is not true you maybe don't know whether it's false.

What you might be claiming is that we've got no good reason to say it's true or to say it's not true. For example, in mathematics, Goldbach's conjecture, which says every even number is the sum of two primes. We can look at every even number we've ever come across and we can see it's the sum of two primes. We've never found a counterexample, but what we don't yet have is any definite proof that we'll never find a counterexample, and so we haven't found a reason to be able to say that Goldbach's conjecture is true. But it looks true, so maybe what we need to say is that it's neither true nor false, or at least at the moment it's neither true nor false.

Also, take innocent or guilty. It looks as though they're binary oppositions, but in Scottish courts of law you can have another verdict. You have not proven. So somebody can be found not guilty but that doesn't mean that they're innocent. It means that there was no way of proving that they were guilty, but that we didn't have good-enough grounds to be sure they were innocent.

That's why I think the notion of opposition is quite slippery here. Real binaries are where there is no gap. You exhaust the territory by being one or another, and I think that's true with carbon and non-carbon atoms that make up the matter of the universe.

Something else that you’ve previously mentioned is that, in talk about emotions and certain aspects about the way that we see things in the world, coming at it via binaries can be unhelpful.

Yes. Quite often when we're reasoning we like to think of ourselves as working in binary terms. We might think of something as rational or not rational. We might think of answers to questions being yes or no. We might think of true or false, but when we are talking about our emotions, these are not things that submit to the logic we use to do mathematics and science.

And, of course, the fact that you're happy doesn't mean that you can't also be sad. There can be a little mixture of sadness with happiness. There can be a little mixture of pain in your pleasure. You can have conflicting emotions which seem to be both there at once.

In terms of sensations, there are interesting cases to look at, too. We sometimes think sweet and sour are opposites but it's not quite true to say they're opposites because you can have a sweet and sour sauce. So, you can have sweetness and sour together at the same time, which means they are not necessarily opposites. They can combine, but of course you can reduce the amount of sweetness by adding more sourness, or vice versa. Sometimes we think things are opposites, but if we look more carefully we realise they're different and complimentary, not real opposites.

To go back a bit, to how thinking about binaries affects the way we reason, something else you’ve previously said is that binaries provide a great source of understanding of things in the world and that our breaking things up into binaries is a part of what has made us so successful as a species. How can we effectively work out when binaries are applicable and when we should hold back in being overzealous in our application of binaries to the world?

I think we are quite successful in exploiting even artificial binary dimensions. We know that when we're building computers – and we are such a technologically successful species in that we designed computers to do a most remarkable range of things for us and with us – we’re relying on zeros and ones. We're relying on a binary code that actually built the bits that will then structure the data that gets processed that we manipulate by computational processes to create changes in large-scale computational operations. And from there, we can build up fantastically sophisticated encoding of data and processing of data.

Now, we couldn't do that without those binary dimensions. Analogue computing is still some way off, even though people are talking about it and trying to model it. When we build dynamical systems in computers or we have theories of dynamical processes in nature, we can use mathematics to approximate the continuation of those processes, but we're still using classical mathematical notation and we're still using classical computation to model what looks like a continuous or analogue system.

We are sometimes able to exploit the precision of language or computing to give us tools to look at, to study, to manipulate and to interact with nature, but there are other occasions where it just won't do, and, as I said, sometimes with sensation.

When you've got sensations of temperature on the skin, they don't behave in some nice, uniform way. Things get a little hotter, and hotter, and then unbearably painful. Or they're losing heat and then they're nice and cool temperature, and then they're suddenly a little cooler, and then they flip to being very cold. Sensations don't behave in a well-ordered way.

I think we have to decide sometimes whether the tools we have are too precise for the phenomena we're studying. Sometimes, we have to create models of phenomena and for that we use fictions. I mean, a lot of the modeling we do in science is making assumptions about how well behaved the phenomena are that we study – be they sensations, be they subatomic particles, be they dynamical processes – and the assumptions are literally false. But working within those models as fictions we can nevertheless find out lots of truths and we can use them to intervene and create new tools to manipulate our environment.

In terms of uncovering binaries that exist within nature, just by way of many of the examples you use, they mainly seem to come from the natural sciences. Do you think that when we're investigating things by other means, we should hold off suggesting the binaries that we think of or that we identify? I'm thinking, for example, in a philosophical context, when philosophers are trying to do metaphysics and identify the centrifuge of the world?

Well, there are certain oppositions that are quite useful, even in metaphysics, and if we lose sight of them we don't get a conceptually coherent metaphysics. Objects and properties seem to be different things. You can have entities and then you think of the properties of those entities, and if you think of something – think of a cork, or a bottle, or a glass – and if you describe all the properties it has or try to figure out all the properties it has and then you try to peel all those properties away, what are you left with? Is there some thing that has all those properties, or is it just a bundle of properties?

And it's very important to wonder, that distinction between object and property, is that coming from nature? Is it that, metaphysically, things resolve themselves into objects or their properties? Or does that reflect a distinction in our language and logic between subject and predicate? Some philosophers in the analytic tradition, like Gottlob Frege and Bertrand Russell, thought that the mind, when it uses language or logic, actually thinks in terms of a subject and a predicate, something we name and something that we qualify or describe.

That is part of what we impose on the metaphysics of nature. If you're in the tradition of early analytic philosophy – Frege, Russell, Wittgenstein – you would've thought that logic precedes metaphysics, that these logical categories are our only way of structuring conceptually the nature of reality so that subject and predicate in language and in logic actually is what gives structure metaphysically to the world of things.

Other more hyperrealist philosophers would say, no, it's because there are objects and there are properties that are cognition in our language, as it were, which grew to take on the shapes of divisions that are really out there. So that's a philosophical issue, whether this distinction which is in our thought and which we tend to think of as in our metaphysical conception of reality, whether it comes from the metaphysical nature of things themselves or whether it comes from our ways of thinking about them. And there are just different schools of thought and people trying to find good arguments to set the priority one way or another.

Does metaphysics depend on language and logic or do language and logic take on and mirror the structure of metaphysical reality? That was a question that early Wittgenstein was really concerned with in his Tractatus Logico-Philosophicus.

Where does your opinion lie on this issue?

I tend to think that we get the distinction between object and property from the structure of logic and language. And, therefore, that's a slightly antirealist view of the nature of reality. But, of course, the problem is we can't really know whether the way we structure our thinking about reality, logic and language corresponds to the nature of that reality when we're not looking at it or thinking about it. It's not as though we can take the linguistic glasses off and look around the corner and see whether reality really does have the forms that we think it has or describe it as having. There's no way to directly compare what metaphysically is out there with our conception of what's metaphysically out there.

Why do you think people become radically sceptical about the reality of the binaries you’ve described as existing in the world? Is it because they fall on the side of thinking that it's simply something which comes from language, or is there some sort of deeper mistake?

I think there's a deep mistake in supposing that, because some aspects of reality depend on language or thought, we might make the mistake of supposing they all do. And I think that when you realise that our ways of thinking and classifying and categorising don't exactly line up with reality, or even that we can't even know whether they line up with reality, can tempt you into overgeneralising and saying all of it depends on us.

Of course our ways of thinking and talking about the world depend on our ways of describing it, but that doesn't mean those are our only ways of describing it. To draw that conclusion would be a logical error. That's just faulty thinking. I think some people get tempted by that. They get a little bit bewitched by language and they think that they're just always working inside it, but they're not. They're also embodied creatures. They're also interacting with the world in all sorts of non-linguistic ways. And the world has a habit of imposing itself on you, whether you like it or not. So to believe that it's all a construction of language or our own thinking is, I think, a kind of vanity.

It's almost a sort of early-Christian thought, putting the human at the centre of the world. I think after the Copernican turn and after realising that we're in a much less exalted place than the Christian world would have it, that we really are just an outgrowth of nature. We have to stop having the vanity of supposing that we control and impose all the structure on nature ourselves.

That’s a lovely way to end.