Anyone who’s done an undergraduate degree in philosophy will have been made to read the great philosophers of the past—the 16th and 17th-century rationalists and empiricists, certainly, probably some Kant, and in all likelihood Plato and Aristotle as well. For decades, particularly in the anglophone world, students were encouraged to treat such monuments of the western tradition as Plato’s Republic or Kant’s Critique of Pure Reason not as relics to be venerated but rather as if they’d been published in the most recent issue of a scholarly journal such as Mind. It’s the arguments in these books that matter, so the thinking went, and if these turned out to be deficient when judged against the most rigorous contemporary standards, then so much the worse for Plato or Kant. That great swathes of the Republic or the first Critique survive this kind of treatment is presumably a sign of greatness.

This is one of the morals to be drawn from Rebecca Newberger Goldstein’s new book, Plato at the Googleplex, in which she imagines Plato reappearing on a book tour in 21st-century America. Goldstein’s Plato is our contemporary, a thinker who still has much to teach us about knowledge, truth, goodness and beauty. Her book is also a defence of the discipline of philosophy itself against those she calls “philosophy-jeerers”—who think there are no interesting or substantive questions that can’t be answered by science. Goldstein, as I discovered when I met her in London last week, thinks not only that certain philosophical questions of the sort Plato asked still resonate, but also that the progress of science will continue to throw up new questions which philosophers are well-placed, if not to answer definitively, then at least to frame in a clarifying way.

JD: The subtitle of the book is “Why Philosophy Won’t Go Away”. So you believe that there are perennial philosophical questions?

RNG: Yes. And I believe that there are new philosophical questions, too. As science advances, it keeps throwing up more philosophical questions. My view of philosophy is as a mediator between the scientific image of us in the world and all the other intuitions that we have and by means of which we try to live coherent lives. And some of them we’ve had to give up because of science. That’s philosophy’s role. Take the foundations of quantum mechanics—that throws up tons of philosophical questions. The cognitive neurosciences are throwing up more questions. And who knows what the next wave [of questions] will be?

It’s interesting that you describe philosophy as a “mediator” between science and our common-sense intuitions about the nature of reality. So, on the one hand, philosophy is not, as Locke, for example, maintained, the “handmaiden” of the sciences. But, on the other hand, you’re not saying, are you, that philosophy’s job is just to tidy up what Wilfrid Sellars called the “manifest image” of the world?

Exactly. I do think there are other intuitions, commitments, even attitudes, that, in a Kantian sense, structure our experience and which are very hard to do away with. Some of them, if we’re committed to them, have implications. So philosophy is about maximising coherence. That would be my slogan for what philosophy does—the bumper sticker.

As I read you, you’re arguing that Plato’s enduring importance lies not so much in the particular questions he asks as in his invention of a distinctively philosophical mode of questioning. Have I got that right?

Yes. He laid out the terrain of philosophy. But I think he’s pretty good at coming up with good questions too.

If you had to give the “bumper sticker” version of Plato’s conception of philosophical questioning, what would it be?

Something non-empirical, something that we can make progress with through reason and argumentation. It’s pretty telling that the methodology of philosophy is the argument, exploring implications, thought experiments, counter-examples. Of course, you have to take into account scientific knowledge, but the methodology is not empirical.

A related question about the way Plato did philosophy—specifically about the dialogue form. Would it be fair to say that, in some sense, the form in Plato is the content? Or at least that we have to take the form in which he wrote philosophy seriously.

I think we have to take the [dialogic] form extremely seriously, and also be very sceptical of [Plato’s] doctrines—all of them, including the forms, the body-soul dualism and so on. Plato tells us, in the Seventh Letter, that he writes philosophy with reservations. But he wrote a lot and he chose the dialogue form, so clearly there is something important, philosophically, that he is telling us there. What I’d like to think [he’s saying] is that we can’t do it [philosophy] alone, it really has to happen in the clash of points of view. The things we really have to examine are so constitutive of our thinking that we’re not aware them, and so you need these other points of view. And I like to think that Plato is also telling us the more diverse the points of view the better.

So you’d be sympathetic to someone like Stanley Cavell who says that philosophy ought to aspire to the condition of conversation?

I am, very much. I guess there have been lonely geniuses—Nietzsche was a lonely genius—but even they converse with other philosophers, at least with the texts. When I separate myself from philosophers for too long, I feel the lack, I feel insecure. I need to say something and have one of my abrasive philosophical friends say, “Look, that could mean (a), (b) or (c), and (a) is trivial, (b) is false…” Given that philosophy is argument, you’re not going to test it against empirical reality—you’ve got to test it against other points of view.

You mentioned Nietzsche’s immersion in the philosophical tradition, in the history of the discipline. So two questions about philosophy and its history. First, is philosophy’s relationship to its own past—as compared to science’s relationship to its own past—what makes the discipline distinctive as a mode of intellectual inquiry? And second, it is the case, isn’t it, that certain strains in Anglophone, analytical philosophy are highly sceptical of the value of reading the great philosophers of the past? There’s a possibly apocryphal story about a sign that used to be stuck on an office door in the Philosophy department at Princeton and which read, “Just say no to the history of philosophy”…

The one story that I heard at Princeton was that when they made a [job] offer to Rudolf Carnap, he was told that all faculty members had to take turns teaching Plato. He sent a telegram back: “I only teach the truth.” Think about the logical positivists and their complete denial of what went before—philosophy does do that quite often.

I have to say that I had no great use for the history of philosophy when I was younger. I did strictly philosophy of science, philosophy of mathematics, mathematical logic. To show how narrow I was—the philosophy building at Princeton is called 1879 Hall, and when I got there it didn’t occur to me that maybe the class of 1879 had given the money to build it. I thought, “Of course, 1879 that’s when Frege published the Foundations of Arithmetic.” As if that’s when philosophy began, 1879! So I could not have been more ahistorical. I think it was when I started teaching philosophy… I knew there was a big vacuum in my knowledge of the greats. We had to take an exam on the greats and I did Hume. But I thought the people who did Spinoza were mad. Why would you do a metaphysician like that? Don’t they know there’s no such thing as metaphysics? But then I started teaching courses on the greats—from the 16th and 17th centuries, and also the Greeks—and suddenly I had a context for the questions I’d been studying. Now I could see that they have a history. And I began to see connections between the questions that I hadn’t seen before. And there is a history of progress. So for me, acquainting myself with the history of the subject has been very useful.

If there’s one take-away argument from this book, it’s that philosophy makes progress…

It’s interesting that in order for scientists to be able to argue their triumphalist story, which I buy—that science is our best means of telling us what is—they have to make a philosophical claim, and usurp arguments that have been made by philosophers. [For example], you have to settle what Karl Popper called the “demarcation problem”. You have to be able to demarcate science from other forms of knowledge. And where do you get that idea from? Philosophy of science. Science and philosophy are joined at the hip.

I wanted to ask you about the figure of Socrates, since you can’t think about Plato without thinking about Socrates. How does Plato’s Socrates differ from other historical iterations of him?

Take Xenophon’s Socrates: Xenophon was very determined to show that Socrates was not impious. He wanted to vindicate him against that charge. Xenophon’s Socrates is much more literal, he’s not the slippery fellow [you see in Plato’s dialogues]. And that slipperiness seems to me to be tied up with Plato’s use of the dialogue form. It seems that Plato is indicating to us that it’s the process that’s important. And then in the later dialogues, Socrates disappears. So one thing that Plato is telling us is that you can’t tie yourself to any one doctrine, you can’t tie yourself to a mentor. I think Plato himself, having been the founder of the Academy, was very nervous about his own influence. Influence is not good. Persuasion is good, but influence sits very hard with him. He doesn’t think that learning can be poured into the pupil. He uses, in the Seventh Letter, the image of a fire—the teacher is on fire and then sparks will be given off. I love that he worries about that and about all the ways we find to get back into the cave, that he worries about what happens when one becomes a sophisticated ideologue or the follower of some teacher so that the questioning stops.

Who was the sparkiest or fieriest teacher you were taught by?

I’d have to say Tom Nagel, who was my dissertation adviser. He is a wonderful questioner. He’s got a very probing way about him and I think was very wary of influence. He was a fantastic dissertation adviser. Some of the things I was writing about he had written about. But in discussing my work, he would never bring in positions that he had already developed. He’d listen to what I said and probe that. And I think that’s the way it had to be. I would say something, waiting for the counter-arguments from positions that I knew he already held and that never happened.

The sparkiest lecturer I ever heard—and he was amazing—was Saul Kripke. He would stand there and just catch fire! He was giving lectures on Wittgenstein that eventually become his book, Wittgenstein on Rules and Private Language. You just sort of sat back and watched it happen!

The philosopher and mathematician AN Whitehead described the history of philosophy as a “series of footnotes to Plato”. Do you agree with him?

If that were the case, what a silly field philosophy would be! A 2,400-year-old man had all the answers? I would like to think that what he meant was that this methodology, this view of maximising coherence, was begun by Plato and that he also formulated questions from a wide range of different areas of inquiry—mathematics, epistemology, metaphysics and political theory—and saw their commonality. In that sense, you can say that all philosophy follows in Plato’s footsteps.

Was Plato a “Platonist” in the modern sense of being committed to a claim about the existence of abstract entities, numbers for example?

The one area of philosophy in which Platonism is constantly referred to is philosophy of mathematics. There was apparently a survey done by the American Mathematical Association and something like 98 per cent of mathematicians described themselves as “Platonists”. There is [in mathematics] very much a sense that you’re discovering rather than inventing. So this is a kind of commitment to the existence of the abstract, but necessarily in insolation from the physical—the structure of physical reality is given by the abstract, but the abstract can’t be reduced to sensory particulars. So it doesn’t have to involve a commitment to a kind of Platonic “heaven” that Russell, for example, makes fun of; it can be the claim that reality can’t be intelligible without referring to abstractions which cannot themselves be reduced to anything other than themselves.

Was Plato a Platonist? Well, there’s the Platonism of the forms which I think he gave up. In the Parmenides, he really criticises the theory of forms. It’s interesting that Socrates is a young man there and he can’t answer Parmenides’ questions. In the Timaeus, which is one of my favourite dialogues, it’s not the forms, it’s mathematics that is the key to intelligibility.

Every theoretical physicist I’ve ever known has believed that not only is reality given to us in the language of mathematics, but that when we have two empirically adequate theories, you go with the one that has the most beautiful mathematics—that’s in the Timaeus too. That’s a Platonism that’s still working. When my scientist friends say that the structure of reality is given in the most beautiful mathematics, I say to them, “That’s a metaphysical argument you’re using right there.” Steven Weinberg said of string theory, “Maybe it’s not true, but we’re going to find some application for it, because never in the history of science has it been the case that such beautiful mathematics didn’t somehow reveal reality.” Whoah! That’s Plato!