 Hi, I'm Peter Adamson and you're listening to the History of Philosophy podcast, brought to you with the support of the Philosophy department at King's College London and the LMU in Munich, online at www.historyoffilosophy.net. Today's interview will be an interview with Robert Pasnow, who is professor of philosophy at the University of Colorado Boulder, and we're going to be talking about substance and the transition from medieval philosophy to early modern philosophy. Hi, Bob, thanks for coming on the podcast. Great to be here. You've written a book about this general historical period, which basically goes from the death of Thomas Aquinas to the publication of Locke's essay, which is quite a large historical span. So I wanted to ask you, first of all, what led you to write a book with that kind of historical periodization? Yeah, it felt to me like, obviously, a lot of work is done on high scholasticism of Aquinas in his era. An even greater amount of work is done on 17th century philosophy from Descartes forward. But hardly anyone has tried to tell the story of what happens between the two. And I just thought, this is something that needs to be done. And so I set out to do it at least in a narrow sort of swath of territory having to do with the metaphysics of substance. And in fact, that's in the title of the book. So the book is about metaphysical themes during the period from the late 13th century to the early 17th century. That's right. Yeah. So the book goes all the way through Descartes up to Locke. Officially, it stops in 1671, which was when Locke wrote the first drafts of his essay. And I stopped in 1671 because I just couldn't bring myself to try to talk about Spinoza and Leibniz, who were very difficult. And I thought, well, I've got to stop somewhere and I'm stopping there. Right. And do you think of that in some sense as the history of scholasticism or of late scholasticism? Or would you be reluctant to apply the word scholasticism all the way down into the 17th century? No, I think it's fine to think of scholasticism as running through the 17th century and even into the 18th century. It took a long time for scholastic philosophy to go out of existence. There may even still be places in the world today where people could properly be thought of as scholastic philosophers. The defining features of scholastic philosophy as I think of it are that it's done in the special context of the university as that began in the 13th century. And it's done from an Aristotelian point of view. And so it's filled with Aristotelian jargon and Aristotelian doctrines. It typically takes the form of the medieval disputation. But one way or another, it has a very kind of technical structure that's characteristic of university learning at that time. And one of the things that's also typical is that they'll use Aristotelian language even when they're taking very anti-Aristotelian positions. Yeah, that's right. So, yeah, so the terminology remains and typically they'll think of themselves as Aristotelians, but people develop rather different ideas about what counts as Aristotelianism. In fact, one sort of point that you make in the book is that there are doctrines like, for example, hylomorphism, the view that a substance is made of a form and matter that pretty much everyone can subscribe to despite the fact that they totally disagree about what it actually means. Yeah, that's right. So people use the same labels for things but mean radically different things. And so it's very dangerous to talk about scholastic views as if there's just one scholastic view on a given subject. One thing that became very clear to me as my research on this book developed was that there's as much variety among scholastic authors as there is in any period in the history of philosophy. It just runs as broad a spectrum of views as you'll find anywhere. And do you find that any difference in the historical period in terms of external constraints, I mean on basically what they could get away with saying, does that change a lot from the medieval period to the early modern period? Yeah, and I think that's part of the story. One of the most interesting periods of scholastic thought is the early and mid-14th century, the era of Ockham, John Buridan, Nicholas of Haute-Racourt, where you get increasingly adventuresome versions of Aristotelianism. And it looked to me in my research as if that whole program gets shut down right around the middle of the 14th century because of a series of condemnations. And that authors after that point in the scholastic tradition tended to be much more cautious and that cautiousness, it ebbs and flows, people become more adventuresome in some parts of Europe than in others. But in a way, it remains all the way through the scholastic era until you get to the 17th century. And that's really when you get philosophers willing to stick out their necks again and arrive at radically different kinds of views, views that are clearly anti-Herestotelian. That's interesting because I think a lot of people would assume that the medieval period is going to be distinguished by very high level of constraint on intellectual debate. So I think it's interesting and maybe surprising that you mentioned the early 14th century as a kind of high point of liberality in terms of what people could get away with. Yeah, I mean, of course, there were predictably things that could not be defended. You could not be an atheist in the 14th century. At any rate, you couldn't say those things or publish those things. But as far as philosophical topics goes, there's a huge amount of vigorous dispute among pretty much any topic you can think of. And you do cover a lot of topics in this book, so everything from matter to form to qualities, you name it. So I thought we could concentrate on maybe the most fundamental question, which in some ways plays a role throughout the whole book. And this is the question of substance. People famously moves away from Plato by considering the most real things to be hylomorphic compounds. So this is a form with matter. And a typical example would just be a particular animal or a human being. And I guess it would be fair to say that pretty much all the philosophers you look at in this period, that's what they think of as a substance in the first instance. Yeah, that's right. So the book focuses on the metaphysics of substance. And if you ask, well, what is a substance, I think it's fair to say for all of the authors I look at that the paradigm cases are animals and other living things. So as far as that question goes, there's a great deal of consensus all the way from Aquinas through later scholasticism. And also in the famous 17th century authors like Descartes and Hobbes and Locke, they're also in substantial agreement that those are what the substances are and that the substances are the fundamental beings in the world around us. So that basic level of ontology or maybe one could say the assumption that our ontology should start from there, from basic substances like animals and plants, that's not one of the things that gets overthrown from the medieval period in the early modern period. Yeah, that's right. So you get consensus on that point. And so, I mean, it is very clear when you look at the history from the 13th century to the 17th century that you do, at a certain point in the 17th century, you do get a radical transformation. It's not as if there's a smooth continuum of views such that any dividing line would be arbitrary. No, there's a real non-arbitrary dividing line in the early 17th century when you arrive at people like Francis Bacon and Galileo and Descartes. They're doing something importantly even radically different. But all these authors agree, despite that difference, all these authors agree on what substances are roughly speaking. Where the disagreements are so interesting is when you ask questions about, okay, what are these substances composed of? What are the metaphysical ingredients of substance? That's where things really get complicated and interesting and contentious. And I guess that a lot of the debate concerns the concept of a substantial form. Yeah, so you might think the most basic scholastic thought is, of course, the hylomorphism, that substances are a composite form that is a substantial form and matter. And so a lot of my book goes through those two separate kinds of cases. What is matter? What's its structure? And then what is substantial form? And how does it connect up with matter? And we could spend hours talking about either one of those issues. But I think the most characteristic dispute and the dispute that goes the farthest and interacts with the largest number of issues is the dispute over substantial form. If there's one central issue that divides the scholastic authors from early modern authors, it's really the debate over substantial form. What does that debate concern exactly? Is it the debate over whether there is actually a substantial form? Yeah, that's part of what's at issue, even whether there is a substantial form. I think the way to think about this topic is that scholastic authors wanted to articulate what a substance was, like everyone did during this period. And the core thought behind hylomorphism is that you can't get a substance just by having a chunk of matter. Just a chunk of matter is not a substance. A chunk of matter is just a chunk of matter. And it's not one thing in the way a substance is supposed to be one thing because it doesn't have the right sort of unity. It doesn't persist over time in the right sort of way. And so if you want to identify what makes a substance a substance, you need something more than matter. And the Aristotelian answer, of course, is that you need a form. And that's the substantial form then that takes a chunk of matter and makes a substance out of it. By giving it unity and organization. That's right. By giving it both unity at a time and unity over time. And it's important to distinguish those two and sort of think about them separately. So a chunk of matter, is it one thing? Is it a million things for each of its different particles? It's not clear how to answer those questions because what would individuate it? What would serve to demarcate it from anything else? So associating a single substantial form with a chunk of matter then makes it a unity at a time. And the same sorts of points hold over time as well. How do we know when that chunk of matter becomes something different? If a piece falls off of it, is it something new? If you break it in half, what do you say then? What about if you just take off a quarter of it or an eighth of it? All of these questions seem very arbitrary and difficult to adjudicate. But if you think of it as having a substantial form, then you can make sense of what it is that individuates it over time. And I guess this will also give us the ability to tell things apart. It's not just keeping one thing the same over time, as we were just talking about. But it also explains what makes you one thing and me another thing. We're both humans, but you have one substantial form of humanity and I have another substantial form of humanity. And that's what keeps us from being the same thing or having blurry edges between us maybe. Yeah, that's right. So when you have an ontology that includes substantial form, you can then say, okay, this substance is different from this substance because they've got two different substantial forms. But you can also say things like the two different substantial forms are forms of the same kind. They're both human forms. And so these are two human beings. Whereas the substantial form of you and the substantial form of your dog are very, very different even if the underlying matter is the same. And so that's what makes you be of two different species. And so a theory of substantial form gets you these very metaphysical points about individuation, but it also gets you a whole, basically a biological framework that divides things into species and genus and you can give a whole taxonomy of the kinds of things that there are. And were they worried already about something that would worry us now today if we tried to have this kind of ontology, which is precisely the kind of blurry edges between one kind of form and another? I mean, if you factor in something like evolution, then you have to admit that the edges between, say, an ape and a human are blurry. Were they worried about that sort of thing? So that was one of the great debates of the 17th century. I think it's fair to say that scholastic authors weren't much worried about that. I hesitate a bit to say that because I think we still don't know that much about scholastic philosophy. There are lots and lots of people that have never been read. There's lots of research out there that still needs to be done. And so I wouldn't be at all surprised for somebody to come along and point to some obscure 15th century figure and say, look, here's somebody worrying about blurry edges and boundaries and all of that. An anonymous commentary on the parts of animals. Yeah. Yeah. Yeah. I mean, so I hate to say no, scholastic authors weren't worried about it. And that's my earlier point that you just can't generalize. But we do know very famously that in the 17th century, that became a huge issue. And especially it became a huge issue in the work of John Locke, who thought precisely that there are no hard and fast boundary lines between species. And that what you've got is you've got a smooth continuum among all living things, such that even in the case of human beings, what counts as a human being and what doesn't count as a human being, there's all sorts of in-between gray area cases. And that was part of Locke's reason for rejecting the Aristotelian framework, because he thought substances didn't come in neat kinds, like the theory of substantial form tended to suggest. I guess another kind of demarcation line that they need to draw if they want to hold on to these substantial forms is the one between substantial form and accidental form. And the idea here would be that some of my properties or features are essential to me being rational, being alive, and some of them are not. For example, being bald is not essential to me, so I could get a hair transplant and I would still be human. In fact, I was human before when I had hair, which was a number of years ago. And I assume this is yet another thing that gets challenged as the tradition goes along, whether you can really draw a hard and fast line between essential properties and accidental properties. Yeah, absolutely. So in talking about form, I was talking about substantial form and setting the accidental forms aside. You can do that in the scholastic context pretty readily because they make such a sharp distinction. Substantial forms are essential to a substance, whereas accidental forms are, well, they're accidental, they're contingent. In fact, the standard definition of an accidental form is it's a form that can come and go while the substance remains. And so if you've got a picture of there being hard and fast rules for when substances come into existence and go out of existence, then you can say, okay, so this is the substantial form, and then all of the other stuff that comes and goes, those are the accidental forms. But as soon as you call that framework into question and you start to sort of wonder whether we can be so sure of when you've got a new substance or when one goes out of existence, then that will destroy the whole substantial accidental distinction. It calls the whole thing into question. And even if you don't mind talking about forms, it becomes entirely unclear which ones are the substantial and which are the accidental. Right. Let's actually think a little bit more about that kind of transition from one substance to another or maybe a substance being destroyed. For example, let's take a human who dies. The human dies, and then you look at what's left, you see a corpse, but it still pretty much looks like a human. I mean, it's not moving anymore, but it has the same shape. You might think that it's still made of flesh and bone, although perhaps some of them might deny that. And I know from looking through your book that there was actually quite a lot of debate about this question. So the question of whether and to what extent there are forms that survive through a transition like that and maybe even substantial forms, even if the substantial form of the human is lost. Yeah, this was a huge scholastic debate. One of Thomas Aquinas' most famous and characteristic views was that all substances have a single substantial form. So in the case of a human being, each human being has a single substantial form that is the rational soul. And by putting his view that way, he was able to make a substance be an incredibly strongly unified sort of thing held together by just a single substantial form. But a consequence of that sort of view was that when the substance ceases to exist, the substantial form ceases to exist, and all that's left on Aquinas' view is prime matter. That's a very startling thing to say if you think about it, because in the cases you were just describing where an animal ceases to exist and what you've got left is a corpse, Aquinas can't quite say that. He can say, well, it looks as if you've got something left over from the animal that's the corpse. But in fact, the only thing that endured through that change from living to non-living is the prime matter. And the fact that that prime matter looks to be the same body is in effect an illusion. It's not the same body. It's the same prime matter, but all of the sensible characteristics of it, those are changed. Those are new. All of its accidental forms are something entirely new. It's a very hard theory to believe actually when you sort of stop to consider all of its implications. One kind of colorful example that Aquinas' opponents like to appeal to was the scar on a human being when the human being dies. The corpse will have that very same scar, or so you would think, but Aquinas can't say that. He's got to say that, no, all of the properties of the thing, all of its accidental forms, all of that are something entirely new. Why do they resemble the properties of the living body? Well, on his sort of theory, that's something of a mystery, and that's something of an embarrassment to his view that subsequent Thomists tried to explain, but that's definitely a weak point in his theory. Why can't he just say that although the substantial forms depart when animals die, this same accidental forms, numerically one and the same accidental forms, can survive, for example, the scar? He can't say that because he's so, so strict about these principles of individuation we were talking about. He thinks that the substantial form individuates, it individuates the whole substance, even including its accidental forms. So nothing remains when a substance is corrupted except for the prime matter. Change goes all the way down to prime matter. And so everything that seems to endure, he's got to tell some story about how it just looks the same. It's not actually the same. And I guess the opposed view to this would be the view of plural forms. Yeah. There were a lot of, that's a very complicated story. And in my book, I go through a lot of different variations on ways in which you could reject Aquinas's view. But the most common sort of way to respond to Aquinas was to propose that at least some substances have multiple substantial forms. And if you say that, then you can say that when a living thing dies, its soul, one substantial form, ceases to exist. But you can say it still has one or more other substantial form that continues. And so the standard move, and this is something, for instance, that John Duns Scotus thought, the standard move like Scotus's is to say that a human being has a rational soul and then also has a form of the body. The rational soul, of course, ceases, well, the rational soul separates from the body. It doesn't cease to exist. It doesn't cease to exist. Yeah. We don't want to put it that way. That's the good news, by the way. Your rational soul will be fine when you die. That's right. Separates from the body. On Aquinas's view, that's the end of the body. On Scotus's view, no, it's not because there's another substantial form. The body has its own substantial form and that endures after death. And that's why the corpse seems so much like the body you used to have. On Scotus's view, it is the body you used to have. And that obviously is a much more intuitively plausible view when you think about it from that point of view. To what extent is this whole debate something that actually reflects worries that are theological in nature? I was just wondering, maybe someone would take this or that view on substantial form because they were interested in something like the transubstantiation. So, for example, you know, you turn this wafer into the body of Christ. It looks exactly the same, but it's not bread anymore. It's the body of Christ. And I would imagine that someone like Aquinas would think that his view takes account of that really nicely. Yeah. Yeah. No, that's absolutely right. It's a tricky thing about working in medieval philosophy. If it's the philosophy you're primarily concerned with, then there's a kind of tendency to set aside the theological considerations as not really relevant or not so interesting. But that definitely risks distorting these views because a lot of their motivations were from particular theological doctrines. And so in the present case, the doctrine of the Eucharist plays an important role. A funny sort of theological issue, the issue of Christ's body being in the tomb for three days played a very important role in these debates because this is something that Scotus in particular appealed to because he wanted that body to be the body of Christ for those three days in the tomb. And he thought that on a view like Aquinas's, you can't get that result. But if you can't get that result, then what does that theological doctrine amount to? Actually, I have to say that seems like a really good point. Typically for Scotus, he's your man for good points. And what happens to this debate as we move forward through history? I mean, I guess that at least the sort of cliche idea about the 17th century is that they get rid of substantial forms, they all become corpuscularians. In other words, they think that matter just consists of particles that have an accidental composition relation to each other. And so effectively, in a way, both sides of this debate lose the Unitarians about substantial form and the Pluralists about substantial forms because substantial forms just get erased from the ontology. Is that what happens? That's a brief version of what happens. But the actual reality on the ground is much more complicated. Throughout the Scholastic era, this debate over one substantial form or many substantial forms carries on undiminished and there's no consensus view. When you get to the 17th century, it's true that in a way, the whole debate gets thrown out. But if you look carefully at what's going on, that's not exactly right. After all, even authors who want to reject Aristotelianism, they need some story about what unifies a substance. And so you find in various people different sorts of strategies. Leibniz is the most famous example. Leibniz is quite explicit about wanting to hold on to substantial forms. And so that's an interesting case to look at in this context. Leibniz, at some level, is a committed corpuscularian philosopher, but he thinks at the level of metaphysics, you need substantial form. Descartes is a different kind of case. Descartes doesn't have substantial forms in general. That's very clear. But some of the time when he talks about the mind, the human mind, he treats it as a substantial form. Now, there's a lively debate among scholars as to the extent to which Descartes really is treating the mind as a substantial form. And in my book, I argue that really not so much. It's not really so much of a substantial form in Descartes. But you can see in Descartes something like the after effects of the pluralistic conception of form that I was describing in Scotus. Because when Scotus distinguishes between two forms, a form of the body and the rational soul, and then you fast forward to Descartes, you can see Descartes just simply rejecting the form of the body. He doesn't have any interest in that. He thinks you can give a purely mechanistic account of material stuff. But when it comes to the soul, Descartes is willing to say, well, okay, we do have a mind. It's immaterial. If you want to call it a soul, we can call it a soul. He couldn't say that from the point of view of Aquinas because Aquinas' soul is the only substantial form. It not only governs the intellectual part of us, but it also governs the body. And that's a model for a soul that Aquinas can't allow. But something like Scotus' model has some kind of... Well, it can get some traction within a Cartesian framework. And so you might think of Descartes as taking that pluralistic conception of substantial form and throwing up part of it, but keeping other parts. Is there a way then that we could even think about the famous Cartesian dualism of body and soul or body and mind as a reaction to the pluralism debate? Because effectively what he's saying is, well, say whatever you want about the body. That's one thing. And then there's this other form, which is the mind on the other hand. And thus, I mean, I think most people think of the Cartesian dualism debate as being a kind of move towards something like a more platonic view of soul rather than Aristotelian view of soul. But the story you just told makes it sound like it came out of a completely different trajectory. Yeah, absolutely. You can think of this debate between Aquinas' single soul view and the pluralist soul view as having an impact on someone like Descartes. Descartes takes it in a certain direction. It leads him to dualism. And so you can think of pluralism as a step toward Cartesian dualism. Conversely, Aquinas and his followers looked at the plurality of substantial forms doctrine. And one way to think about their criticism of it is precisely that they were turning human beings into something that was a duality. They don't quite put it that way. But from our vantage point, seeing that Descartes is on the horizon, you can very much look at Aquinas and see him saying, we don't want to treat a human being in a dualistic fashion. We want to think of there being one soul that is both the mind and the organizing principle of the body. And so that's not to say that Aquinas is not a dualist in any sense, but Aquinas is definitely not a Cartesian dualist. He has a very, very different metaphysics. So if Aquinas could have read Descartes, he probably would have said, see, I told you this would happen. Exactly. Yes. Yes. And I'm sure you can find late scholastic authors saying just that, defending Thomism on the grounds of exactly Descartes is just a version of this bad, scotistic plurality of forms doctrine. OK, well, that seems as good a point. And as I need to end on, and it certainly shows the perennial importance of medieval philosophy and debates within scholasticism for the later period. So thank you very much, Robert Paz now, for coming on the podcast. My pleasure. And as we've just seen, there would be a very strong case for just continuing on into what I'm going to be calling the Renaissance period and then into early modernity. But there's something that we need to cover first, which is Byzantine philosophy. And so I'm going to be moving back a few generations or centuries in history to pick up that story of the continuing philosophy in Greek before moving on to the Renaissance in Western Europe. So please join me for that as we begin to look at Byzantine philosophy here on the history of philosophy without any gaps.