Note: this transcription was produced by automatic voice recognition software. It has been corrected by hand, but may still contain errors. We are very grateful to Tim Wittenborg for his production of the automated transcripts and for the efforts of a team of volunteer listeners who corrected the texts.
Peter Adamson: It's great to have you on the series because we're going to be talking about John Buridan and you're someone who's published a lot about him, including a book about Buridan, which is subtitled Portrait of a Fourteenth-Century arts Master. And I take the subtitle to be an indication of the importance of the fact that he remained in the faculty of arts, which is unusual. I mean, he doesn't join one of the orders, he doesn't become a Franciscan or a Dominican, and also he doesn't join the theology faculty. So in this respect, he's unlike a lot of the other major medieval philosophers we've looked at, like Aquinas, Scotus, Ockham, and so on. So what do you think that these biographical facts tell us about his philosophical project?
Jack Zupko: Well, I think actually that they tell us quite a bit about Buridan, but it's all indirect, because he never himself tells us why he remains a career arts master, why he doesn't join a religious order like the Dominicans and Franciscans. But there would have been reasons for doing so. The normal career path for an academic in the fourteenth century in Paris was to study for your arts degree, become a master, and lecture in arts, and then move on to an advanced faculty, very often theology, and support yourself as a theology student by lecturing on arts. We have evidence of this as well. Not uniquely, but unlike almost everyone else we know from the period, Buridan remains for his entire career, for almost thirty years, in the faculty of arts at the University of Paris, and remains an arts master without ever advancing to the faculty of theology, or as far as we know, ever attempting to earn a theology degree.
Peter Adamson: And that's despite the fact that he was pretty well known in his own lifetime as a very smart guy.
Jack Zupko: Indeed, he seems to have made a career for himself as a secular master. And in my view, I think you can find some evidence of this in his writings. He seems very conscious of this fact, and very conscious as well of his role in commenting on Aristotle, and of the idea - and you see this in his works from the 1340s and 1350s - of the idea that perhaps philosophy is a secular enterprise. Now, that in itself wasn't terribly surprising, I don't think, because Thomas Aquinas, for example, never refers to a Christian as a philosopher. For him, philosophy is a pagan activity. Right?
Peter Adamson: Augustine's not a philosopher, Augustine's a theologian.
Jack Zupko: Exactly, right. So that's the sort of - and you can see how that was kind of translated over into career paths and so on. But Buridan takes this a little bit differently. For him, a philosophy is indeed a secular, not a pagan activity, but it's different from theology. And the reason I say this is because he never in his writings, to my knowledge, refers to theology as a "scientia," or a science in the Aristotelian sense, meaning a body of knowledge. And that's quite significant. Now, it wouldn't have been his place as an arts master to pronounce on theology - he would have gotten into trouble for that, for sure. But it's telling that whenever he uses the term scientia, right, which is knowledge which philosophers should be concerned with, he doesn't ever say that this form of knowing exists in the faculty of theology. He more typically says: 'the theologians will decide for themselves,' and kind of pushes it off. But I think that we can, in many places - we can read that as saying, he's skeptical about whether you can have genuine scientia in theology.
Peter Adamson: I guess then your idea is that he really wanted to have certain knowledge, and that's what his goal was in his writings, and he thought that was something he could only achieve in the secular philosophical arts faculty.
Jack Zupko: Well I think, and it's also tied together with this notion - and this is what I tried to push in my book - of placing philosophy on a new and secular foundation. By which we mean not a theological foundation. So this is something that could be respectfully pursued by someone who's a Christian. And it would be involved with questions - a menu of questions if you will, that were determined by Aristotle and the commentary tradition on Aristotle's writings that would begin in logic, "the art of art and science of sciences" as Peter of Spain said, and move out from there to metaphysics, natural philosophy, ethics, and so on. And I see this as a very significant change from the way philosophy was done, not just from the way philosophy was done in the 13th century, but also among his peers.
Peter Adamson: And in fact it seems like a premonition of what's to come in centuries later, early modern philosophy and so on.
Jack Zupko: That's the harder part of the argument, and I certainly don't want to suggest that really modernity in philosophy - forget about Descartes, it begins with Buridan. That's much too strong a claim. Well, it's possible that we could advance this, but we have a lot of filling in to do. So we know that Buridan as well was terrifically influential in the universities, especially in Eastern Europe and Northern Italy. His students went out and then took copies of Buridan's writings with them and used those writings as the basis for their own commentaries on Aristotle. So we have this kind of chain of transmission and we don't know a lot about it going into the 15th century, but the more we learn about it - and we continue to see Buridan's hand and Buridan's influence in the way books like De Anima were read. We'll one day be able to have a kind of seamless story between late scholasticism and the early modern period, Descartes and thinkers like that.
Peter Adamson: And there's no doubt that Buridan will be a major part of that story.
Jack Zupko: I think so. I think so just because of the way he does things.
Peter Adamson: Now obviously the arts faculty was not invented to facilitate this sort of project. It's intended to train younger students. And something else that you in fact emphasize a lot in your book is that Buridan was a teacher and that his writings were produced in a pedagogical context. What does that mean for us as readers of Buridan? How does it affect the way that we should follow through a commentary on Aristotle or other works that he wrote?
Jack Zupko: Yeah. It means that we should be careful - or at least I've always found when I read Buridan, careful about surface appearances because sometimes things can appear fairly straightforward and simplistic because he is teaching. He is trying to tell arts undergraduates what they need to know about Aristotle. But if you look further and read more deeply, you see that he replies to questions in ways that very much engage the arguments and that signal important shifts in position, including shifts away from Aristotle. But it's all done in a kind of subtle fashion. And so when you read Buridan, you shouldn't expect the writer of independent treatises saying 'here are the principles of philosophy and here is how it goes.' Working in a commentary tradition, he was guided initially by authoritative texts. And those were not just the texts of Aristotle, but in logic texts like Peter of Spain. So there was a textbook tradition of logic. Buridan does amazing things in logic. He revolutionizes logic, but he does it within this commentary context on Peter of Spain. And you have to read far enough to see what he's doing.
Peter Adamson: This is just the latest example of something that we've seen really throughout almost the whole history of philosophy now, which is that often the most innovative thinkers are presenting their ideas within the context of writing commentaries. We saw it in late antiquity. We saw it actually in the later Islamic period, even later than Buridan. We've also been seeing it throughout Latin medieval philosophy.
Jack Zupko: Yeah, unfortunately, I think the commentary as a genre is not well thought of in our world. People imagine, 'well, a commentary, that's not original. And how could we find good philosophy in a commentary? It's simply someone riffing on themes that have been discussed by others.' But that's very far from the truth. Really, a lot of things were going on in commentaries and a lot of original work as well.
Peter Adamson: But on the other hand, it seems like the teaching context would impose certain limits on Buridan's project. So it's something you've already mentioned is that he doesn't see it as part of his task, or even maybe he doesn't see it as something he's allowed to do, to venture into more theological territory. And I guess that one might also say he's not going to stray too far from the topics that - let's say, Aristotle, has set in the source text, because otherwise he's not writing a commentary anymore.
Jack Zupko: Yeah, yeah. So the genre, and not specifically the commentary, but the subject matter. And so the curriculum of the University of Paris for undergraduates was what determined what Buridan was was lecturing on. But he doesn't stray too far away. But again, under or beneath that rubric - I'll give you an example that that might bring this home, not so much with Aristotle, but with Peter of Spain: His logical masterwork, the Summulae de dialectica, which became the logic textbook in most of Europe for several hundred years afterwards, is written as a commentary on Peter of Spain. So you go into that and you find Buridan treating sometimes some very old material, doing logic in a way that was no longer done in the 14th century. But he reinvents things. And there's one place, the fourth treatise on supposition, where he thought Peter of Spain's remarks were just so badly done that he took them out and replaced them with his own. So it's not a commentary, right? But he rewrites the source text so that it should say what it should say and works from there. So there's actually, I think, quite a bit of room for inventiveness within the genre. And indeed, within the pedagogical context of the university.
Peter Adamson: And of course, even in earlier generations, we see people like Scotus really bending the notion of what could be in a commentary. Say a commentary on the sentences of Peter Lombard. It's not like they're just quoting each sentence of Lombard and then saying what Lombard means. They change it into a question format where they handle one topic after another.
Jack Zupko: Yeah. And indeed, there's a distinction within the genre between the "expositio," which is a literal commentary, typically a line-by-line exposition of the authoritative text, and the "quaestio," which is, as it suggests, a question based on the text. And the question usually comes from a lemma from the text. And these quaestiones develop lives of their own, so that you'd see arts masters treating the same questions and responding to each other and each other's arguments in the context of these questions.
Peter Adamson: And that gets them quite far away from the original source. Well, now moving on to the content that gets presented in these works: I guess the thing that Buridan is most known for is being a nominalist. And something else that you argue for in your book - which kind of surprised me because I think of the 14th century as a time where realism and nominalism are jousting for supremacy. You say, 'well, not really, because in a way, Buridan could take nominalism as the default position.' He basically felt that that position had won the day, as it were. And thus, you suggest that we shouldn't see him so much through the lens of nominalism as such, as see him as what you call a parsimonious thinker. And so I'm wondering whether you could say something more about what you take that to mean.
Jack Zupko: Sure. I think that for Buridan and indeed for other 14th century thinkers, nominalism is not a bit of doctrine, right? It shouldn't be thought of as a position on whether there are real universals or not. That was a part of it, and nominalists did hold this view. But to my mind, and certainly, you know, Buridan is a very good example of this, nominalism is a method. It's a way of doing philosophy, and it's guided by a new way of doing logic that begins to be practiced by people like William of Ockham and is perfected by Buridan. And it involves an important change in semantic theory. In particular, the most important of those changes is the shift in theory of predication. So before the new logic, the standard theory of predication was called the inherence theory. Roughly, a sentence is true just in case the predicate of the sentence inheres in its subject. Now, of course, you can see that if you look into this further, you have to do quite a bit of metaphysics, right, in order to understand the phenomenon of predication. The new logic, the terminist logic that Buridan and Ockham practice rejects this. It says roughly that a sentence is true just in case the subject term stands for the same thing as the predicate term.
Peter Adamson: They both have the same supposit. Thus the same object in the world satisfies both the subject and predicate term.
Jack Zupko: Precisely. So we bracket or shove aside any notion of inheritance, or predication becomes more a question of reference, right, of individuals in the world. And that completely turns around semantic theory and allowed semantic theory to be disconnected from very thorny metaphysical issues that it had really bogged down with from the time of Abelard on.
Peter Adamson: Just to make sure that I get this, the difference then would be if you take a sentence like 'Peter is bald,' which sadly I am. So the first initial position, the inheritance position, is that baldness somehow inheres in me or exists in me. And of course, then that puts the onus on the proponent of this theory to say what my baldness is. Because it's evidently a real thing out of the world.
Jack Zupko: What's the quality baldness? That's a kind of universal. It's a common nature. Is it a property that you share with others and so on?
Peter Adamson: And it fails to inhere in you because you have a nice thick head of hair. But it does exist in Telly Savalas, the star of Kojak. And on the new logic view, you say, well, the reason the sentence is true is that I satisfy the name Peter, because Peter refers to me, and I satisfy the predicate baldness, because I'm bald.
Jack Zupko: Bald man, right? Or bald individual - and Peter are the same person, right? The same individual. So the sentence is true.
Peter Adamson: Okay, right. Now, what does Buridan bring that earlier nominalists hadn't in defending this way of thinking about predication or does he take it so much for granted that he feels like he doesn't need to defend it?
Jack Zupko: I think it's the latter. I don't know of any place where he offers a kind of defense of this as the way. It's his very methodology. And going back to the book, I think it's what characterizes his kind of philosophical outlook. So it's not the case that there weren't people around in the 14th century who believed in real universals. Walter Burley, you know, is a kind of realist who believes in universals. But it's the way in which you think about subjects and predicates and common natures and so on. And the way in which they're used in arguments and the way in which the truth conditions of those arguments are explicated that makes all the difference. The other thing I would say there too is that for Buridan and most of his contemporaries, if you talked about realism, for them initially at least, it was Plato's realism, which they only understood in cartoon form from Aristotle's metaphysics, you know, who has all kinds of arguments against it. And in Buridan and other 14th century authors, not having Plato's works, right, Platonic realism was hilarious, right? 'Surely you're not a Platonic realist!' was typically the way they approached it.
Peter Adamson: Poor Plato.
Jack Zupko: Yeah, yeah, it's sad. I think, you know, they certainly had respect for him, but the respect - and they knew, of course, that they only had the first half of the Timaeus, right, in Latin. But on the question of universals, virtually everyone thought that Plato's view was a non-starter.
Peter Adamson: Because they're basically just using Aristotle's critique of Plato as their source for knowledge about Plato. One advantage, I think, of seeing him as a parsimonious thinker, instead of concentrating on this debate about anomalism and realism concerning universals, is that we can apply this conception of his methodology in other areas of his philosophy. And one that we should probably mention, because you're part of the team that's producing the translation and edition of the De Anima commentary. So the commentary by Buridan on Aristotle's On The soul, his psychology. So what he has to say about the soul, how does his parsimonious approach to philosophy manifest itself in that context?
Jack Zupko: Yeah. Well, there's a couple of different ways. I mean, one way that applies across the board is through judicious use of the Razor, right? So what we know as Ockham's Razor, you know, it's certainly found in Ockham - was not known in the Middle Ages as Ockham's razor. But the notion that when you explain a phenomenon, you know, especially a natural phenomenon, you should use as few entities as you can to construct a satisfactory explanation. That runs throughout Buridan's metaphysics and natural philosophy. I would say that the highest level, it comes out in Buridan's efforts to, I want to use here the term "naturalism" - but I don't mean it in a contemporary sense and quite the sense that we have now. But I mean it in the sense that Buridan resolutely focuses on nature and the way in which the natural world unfolds, and wants to come up with the most parsimonious understanding of that. And if a phenomenon is complex, he's certainly willing to come up with a complex explanation. And we can see this in his writings when he's talking about the propagation of light and vision. He knew this was a complex phenomenon because he had sources from Islamic philosophy and perspectivism and so on that he was dealing with. But along with the naturalism, there's a sort of shying away, if you will, from purely metaphysical explanations.
Peter Adamson: But it seems like this area of the soul in particular is one where, first of all, from our point of view, they're all positing a superfluous entity - namely the immaterial soul, or at least a very controversial entity. I mean, maybe some of the listeners believe in immaterial souls as well. But a lot of people would say, 'well, you don't need that.' And I guess I wonder why wouldn't Buridan be led by his own methodology to say, 'well, actually, if I can have the body performing certain faculties, maybe the explanatory principle of soul in general is just otiose.
Jack Zupko: Yeah, yeah. Well, indeed, if one were to follow the naturalism kind of all the way down, you would arrive at such a position. And in fact, what Buridan does is here is quite interesting where the human intellect of soul is concerned. And this is the controversial item, right? It's the immaterial soul. It's supposed to be in here in the body somehow, and be extended, but not by the extension of the body, right? There's this problem about how something immaterial can be in a place and in here in something physical. When he comes to discuss this question, he says basically, that the position of the Catholic faith, of Christianity, that the human soul is immaterial and yet inherent in the body, is not demonstrable by natural reason. And in the same question he sketches also the position of Averroes, who has a monopsychist position - a kind of single intellect of soul that's shared by all cognizers. And this is the naturalistic position, that of Alexander of Aphrodisias, who has a material intellect. And what's very interesting is Buridan says upfront, that 'a philosopher, without having the benefit of the faith, should agree with the position of Alexander.' In other words, should agree with the material intellect - takes precisely the position you're suggesting. It's just that we know otherwise, and we believe on faith, that the human soul is immaterial.
Peter Adamson: And I take it, you do think he's being sincere there? He's not sort of subtly indicating to his students, 'oh, by the way, the Catholic faith is wrong.' He's actually saying, 'well, we know this doctrine to be true, even though we can't demonstrate it.'
Jack Zupko: Well, 'we believe it to be true.' You see, it's not going to be scientia, because we can argue for it. So in other words, he's happy to enumerate the arguments in favor of the position - as he does in the case of Averroes and Alexander, and the objections. But he says, if you focus on the natural evidence, the preponderance of the arguments are in favor of Alexander. But that's not demonstrative either, or at least it doesn't show that the other views are false.
Peter Adamson: It reminds me a little bit of the late 13th century discussions on the eternity of the world, actually. Where you have people, even someone like Aquinas, will say, 'well, actually, there's no demonstration for the eternity of the world. There's no demonstration against it. The reason that we believe it not to be eternal is that the Bible says it's not eternal,' effectively.
Jack Zupko: Yeah, it's certainly that, but it's also the indicating to students that, look, in holding this position, we're not sort of violating good epistemic principles. So you can't come along and say, "I can demonstrate the materiality of the soul," because you can't do that. And he's quick to point that out. There has been, about a decade ago, an interpretation that suggested that Buridan was, between the lines, a kind of crypto materialist. But I've published on this, arguing that this doesn't hold up, because there's just no evidence of it elsewhere in his writings. I suspect that his approach to this particular question was just one of setting a boundary. Because natural philosophy is concerned with things that are evident to sense, memory, and experience. Following an Aristotelian line, the claim that the soul is something that's not evident in this way, places it beyond the reach of the natural philosopher.
Peter Adamson: One other thing that we should probably mention before we finish is Buridan's thought in physics. I guess the thing he's maybe most known for, other than his nominalism, is his theory of impetus, and more generally, what he does with Aristotelian science. Is that another area where you see this parsimonious methodology having an influence on the conclusions he reaches?
Jack Zupko: Yes, I suppose so. But I guess I wouldn't describe it as parsimony, but as yet another example of Buridan trying to develop explanations that actually fit the phenomena. So historically, at the time Buridan was writing his commentary on the physics, everyone knew that the Aristotelian theory of anti-parastasis was wrong.
Peter Adamson: This is the view that the air comes in from behind and pushes the projectile through space.
Jack Zupko: Right. So if Aristotle's right, then I could say, put a javelin on a tabletop and go behind it with a bellows and pump it quickly, and the javelin would begin to move, because I'm pushing it along. But Buridan knows this is wrong, and he gives us an example. He says he's noticed that on the Seine River, there are barges carrying grain, and these are moving up and down the Seine River. Now you'd expect that of anti-parastasis were true. That is, if the air in front of the barge, where the barge is moving, is being pushed out of the way and going to the back of the barge to fill up the vacuum that's created by the motion of the barge, the sailors would have grain blowing all over them, because it would create a wind that would blow the grain on them. And he says, we don't see this happening, therefore there's something wrong here.
Peter Adamson: Because the grain is loosely piled just to keep the barge from moving.
Jack Zupko: Exactly. So you can imagine there's chaff and so on, and the wind from the motion from the push at the back would go over the top of the boat and blow the grain on the sailors, and that just doesn't happen.
Peter Adamson: It's a brilliant observation, actually.
Jack Zupko: Yeah, so he's very attuned to the natural world and to showing his students just why this theory doesn't make any sense. And he picks up from several intermediaries - the theory comes from Philoponus, the notion that instead we should think of motion as a quality that's in an object that's somehow impressed in it. In the case of violent motion, it's impressed by the thrower of the javelin. And there were elaborate theories of impetus, which talked about how long lasting it was. So a javelin will not keep moving, but the impetus will gradually decline as gravity pulls it down. And he says also, and this is interesting, because you'd think that only a theologian would say something like this - that this is actually a better explanation of the motion of superlunary bodies, the stars and the planets, because God could have put into them at the moment of their creation, an eternal impetus. And that would cause them to acquire the quality to keep moving in the circular fashion that they move or however it is. And that's a better explanation of their motion than anything else that was around.
Peter Adamson: This is interesting. The reason I asked about the parsimony issue in this context is that I could imagine an opponent of the impetus theory, precisely on parsimonious grounds saying, 'well, I don't want this hypothesized occult force that's been impressed into the projectile. I want something that I know is already there.' And Aristotle's theory is better for that purpose, because I know there's air surrounding the projectile. So if the air could somehow be pushing it along, that would be more parsimonious. In that sense, you could even argue that this is a place where he's willing to be less parsimonious, because he wants to account for the phenomena.
Jack Zupko: I think that's right. I think that Buridan senses that Aristotle stumbles on the phenomena here, and that we have to change this - which is important to note, just taking it back to commentaries and authority. He certainly will reject Aristotle's view where he thinks it's wrong. I mean, another place is in the theory of modal syllogistic. All logicians knew that Aristotle's theory had serious gaps in it and was problematic. The real issue was how to fill it in and how to revamp it. And Buridan and a number of other logicians take that task on.