← History of Philosophy Without Any Gaps
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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@historyofphilosophy.net Today's showing good the Port Royal Logic When I got to graduate school, I was required to take a course in advanced logic. It was a struggle. I hadn't taken any classes in logic when I was an undergraduate, so it was only with the help of my better prepared fellow students that I was able to get the homework assignments done and pass the final exam. It was corrected over the summer, so I got the exam back only at the beginning of the following academic year. I remember looking through it, amazed by the fact that even though the solutions were in my own handwriting, I couldn't understand any of it because I'd forgotten everything in the intervening months. Fortunately, since then, I haven't needed most of what we learned yet. I do not regret taking the class because to do philosophy seriously, you really need to have mastered some logic. It's useful just to know what all the symbols and notations mean, and more profoundly to be able to analyze an argument with full, rigorous and as it happens, I've wound up being pretty interested in Aristotelian logic and very interested in the transformation of his system at the hands of Avicenna and other logicians in the Islamic world. Apart from that, I think my experiences with logic have been pretty typical for a philosopher who does not work directly in philosophy of logic. On the one hand, it's useful to have a grasp of the basics. On the other hand, once a card carrying logician gets you in their grasp, they're going to go beyond what is merely useful to explore logical issues more deeply, because the logicians are interested in these problems for their own sake. This pattern is not specific to modern day analytical philosophy. It actually happened in the Islamic world when logicians writing in the wake of Avicenna started to contemplate issues that have no obvious application. Like happens when a proposition contains an impossible subject term, as in square triangle has three sides. In India, the Niyaya school began as an effort to understand Vedic literature, but soon enough started debating technical issues around argumentation theory. In Warring States China, the early Moists set forth utilitarian ethical and political doctrines, but the later Moists composed texts that are purely about language and reasoning. The idea was presumably to use these logical tools to defend the earlier doctrines, but the later Moist writings barely even mention this, and so it was also with Scholastic logic One of the biggest complaints made by enemies of the scholastics was that their treatments of logic had become far too complicated and arcane to be of any use. We see this especially in humanist writers like Lorenzo Valla and Juan Luis Vives, who mocked the schoolmen for investigating the implication of such nonsense statements as only any non donkey belonging to this same man be begins contingently to be black. These humanists also disliked the grotesque, highly artificial Latin used in university Texan logic, but their more principal complaint was that the enterprise was largely useless. We find powerful echoes of this attitude in Cartesian philosophy. Descartes himself said that scholastic logic corrupts good sense rather than increases it, and his admirers set out to replace that logic with something more fit for purpose. This wasn't going to be the rhetorical art proposed by the humanists, but a simpler and more intuitive logic that could be put to use in Cartesian science. Descartes made initial efforts in this direction, as we see with his interest in method. Various successors then competed to provide the definitive statement of Cartesian logic. In 1654, Johannes Clauburg published brought out his Old and New Logic, whose very title indicates his agenda. In the same year, Jacques Durhort published a work covering both Scholastic and Cartesian logic and proclaiming the latter more useful. Durhour then produced an abridgment of true philosophy that drifted even further towards Descartes and away from Aristotelianism. But the competition to produce the standard Cartesian logical text was won by Antoine Arnauld and Pierre Nicole, whose treatise was named after the stronghold of the Jansenists, the Port Royal Logic. It was first published in 1662 and went through four revisions, with the final version appearing in 1683. It has been called the representative par excellence of Cartesian Logic, and for good reason, as we'll see shortly. But the work does not break completely with scholastic tradition. It covers most of the same topics that would be found in a university textbook of logic, and even says some of the same things about those topics. One difference, though, is that Arnaud and Nicole try to avoid the temptation to explore logical questions that go beyond the strictly useful, as they explain in a preface. The Port Royal Logic was conceived as a textbook for a young nobleman, here unnamed, though we know that they are referring to Charles Honore d', Albert, whose aristocratic father had translated Descartes Meditations into French. Originally, Arnaud and Nicole wanted to dash the thing off in a day. In the end, the project proved more daunting, and it took them all of four or five days to complete a first draft that was then expanded to form the published version. For our two authors, the purpose of logic is educating our judgment and making it as precise as possible. Or, as they concisely put it later on, the aim of logic is to think well. Anything that turns out to be unnecessary for that goal is, in theory, excluded. Some more technical material is included because it had always been standard in scholastic logic, but our authors invite their readers to skip them. They also use concrete examples drawn from the sciences to illustrate logical points, to bring home that this is a logic that is to be put to real use. Other authors are criticized for failing to do this and for indulging in pointless discussions that will never lead anywhere, including in other fields like mathematics and metaphysics. People are not born to spend their time measuring lines, examining the relations between angles, or contemplating different motions of matter. The mind is too large, life too short, time too precious to occupy oneself with such trivial objects. When it comes to many familiar questions of metaphysics, like whether the created world could be eternal, they say that the safest thing is to get rid of them as quickly as possible and, after studying cursorily how they arise, to resolve in good faith, to ignore them. This all sounds extremely Cartesian. The Port Royal Logic borrows the impatient tone he takes with the Scholastics as well as the confident tone he adopts when describing his own methods. More than that, it explicitly announces towards the beginning that it will be drawing on Descartes, whose mind is as sharp as those of others, are confused. So it is that canonical items on the usual logical syllabus, like the theory of the 10 categories, the five types of predicate, and the use of standard patterns or topics to devise arguments, are dismissed as a waste of time in favor of clear and distinct ideas. As we saw last time when talking about his views on free will, Arnault thinks it is impossible to reject such ideas. We find that point in the Port Royal Logic as well. Arnault and Nicole write that no marks are necessary to recognize the truth, but the very brightness which surrounds it and to which the mind submits, persuading it in spite of itself. They connect the notion of clear and distinct ideas to the chief concern of Aristotelian logic, which is the analysis and combination of sentences in which a predicate is applied to a subject. In the case of an unclear and indistinct idea like pleasure is good, it is an open question whether the predicate good applies truly to the subject pleasure. By contrast, everything contained in the clear and distinct idea of a thing can truthfully be affirmed of it. If, for example, we clearly and distinctly grasp God as being infinite, then we can be sure that infinity is a predicate that truly belongs to God. These, by the way, are my examples. But I think that Arnaud and Nicole would approve, since they put so much emphasis on the use of examples when explaining logic. Since clear and distinct ideas are perfectly reliable, we might wonder why we need anything else. Why not just stick with the propositions that spell out the content of these ideas and suspend judgment about everything else? One reason would be that we can make progress by combining clear and distinct ideas to produce further conclusions. I'd better give another example. Any Cartesian would agree it is a clear and distinct idea that God is infinite and that no body is infinite. So we can combine these two propositions in a syllogism to yield the conclusion God is not a body. Admittedly, that is pretty easy if not trivial. But the syllogisms do get more complicated than that, which is why we need logic. Though actually, Arnaud and Nicole say that it is pretty rare for people to make mistakes simply because they reason invalidly. Usually error results from false premises, not failures of logic. Maybe this is one reason the Port Royal logic was so. It constantly reassures you that the stakes are pretty low and that the more difficult and technical parts probably aren't going to matter at all. Another reason we cannot make do with nothing but clear and distinct ideas is that we also get knowledge from sensation. Some contemporaries would go further. There are no innate, clear and distinct ideas, perhaps no innate ideas at all. And in fact all our knowledge derives from sensation. Most of us would think here of the British empiricists like Locke, Berkeley and Hume. But when the Port Royal authors think of empiricism, they have in mind a target who is for them closer to home. Gassandi and his followers Arnaud and Nicole cite Augustine for the idea that we do depend on sensation for knowledge, this being a weakness in our minds inflicted by original sin. But we often have conceptions not derived from sense experience, something they illustrate with the chiliagon, meaning a thousand sided geometrical figure, though it sounds more like a lack of supplies at a Mexican restaurant. Examples like the Chili Agon show that Ghassandi was wrong to say that nothing is in the mind that was not earlier in the senses. And in fact things we discover through pure thought are of anything more certain than what we can learn from sensation. Just take our knowledge that we exist, about which we can be certain ghosts. Given the undeniable inference. I think, therefore I am. If there were any doubt about the Cartesian credentials of the Port Royal Logic, that example should banish them. It seems, in fact, that this textbook proves beyond doubt the close connection between Jansenism and Cartesianism. This association, which I already mentioned in the last episode, is also apparently confirmed by witnesses of the time, like one who said in 1690 that there are very few Jansenists who are not Cartesians. But Stephen Nadler, an expert on early modern philosophy in general and Cartesianism in particular, has questioned this judgment. Given our current preoccupation with logic, we might put Nadler's point by saying that such statements illicitly infer a universal judgment from a particular case. Clearly, Arnaud was powerfully influenced by Descartes. The Port Royal Logic wears that influence on its sleeve, and we already saw that his whole thought is shot through with Cartesianism. But as it turns out, other members of the Jansenist movement had their doubts. One friend of Arnaud warned him not to embrace Cartesianism because of the theological problems it would entail. For instance, strict dualism raises doubts about bodily resurrection and transmission of original sin through physical inheritance. One important Jansenist named Le Mastre de Sacy actually rejected Descartes in no uncertain terms, writing, what new ideas can I obtain of the grandeur of God when I am told that the sun is a mass of metal filings and that animals are clocks? He was no fan of Aristotle either, whom he compared to a thief who had usurped power within the Church. But for him, Descartes was like a thief who has killed another thief and made off with his spoils. We might assume that Pierre Nicole, Arnault's co author in writing the Port Royal Logic, must have been a staunch Cartesian, but elsewhere he proclaimed himself neutral on the merits of Descartes, given that his philosophy was full of uncertainties and obscurities. When we recall that another Jansenist, Pascal, included a note in his Pensee stating simply descartes, useless and uncertain, we realize that Arnaud may have been more the exception than the rule in being a stridently Cartesian Jansenist. If so, then a devotion to Descartes is not the only characteristically Arnauldian feature but the Port Royal Logic. I already mentioned that it cites Augustine, which is another sign of his handiwork, and more generally, theological concerns are not hard to detect in the work. With scarcely disguised glee, the logic offers Protestant reasoning about the Eucharist as an illustration of bad logic. These heretics thought that the host does not really become Christ's body in a Catholic Mass, giving the argument that when he said, this is my body at the Last Supper, the word this refers to bread, not body. This argument is dispatched with ease on the grounds that the word this is an ambiguous or confused term. Thus, when Augustus Caesar said, I found the city of Rome made of brick and left it made of marble, the word it refers to something that has been changed precisely in its material constitution, just as happens in the Eucharist. According to Catholics. At the end of the Port Royal Logic, theological concerns again come to the fore as we discover that there is another source of knowledge. Alongside sense experience and clear and distinct ideas, there's also faith, which is the most powerful conviction we can have, but never conflicts with other sources of our knowledge. In one of several clues that Pascal had some input in the writing of the logic, emphasis is put on faith in miracles. And the Protestants, called the heretics of our time, are again attacked in this case for their skepticism concerning the miracles of the saints. The work concludes with an even clearer sign of indebtedness to Pascal, as faith is justified on the grounds that it is more rational to wager for the existence of God than against. Theological concerns seem to have helped inspire a particular focus in the Port Royal Logic. On one topic that looks more relevant to philosophy of language, the theory of signs. A sign is, of course, something that signifies something else. This could be a literal sign, like a placard with a picture of a crossed out cigarette. It could be linguistic, like an attendant on a plane telling someone who's about to light up, hey, this is a no smoking flight, or even a gesture, like a wagging of the figure at someone who fishes out a lighter and a pack of cigarettes. All three are signs of the idea of not smoking. But as Augustine pointed out in a treatment of this issue that influenced the logic, not everything is a sign. A rock is just a rock, unless, of course, someone decides to use it to signify something. Of particular interest to our authors are signs in the form of spoken words, which in themselves are just noises. With regard to this material level, speaking is common to humans and parrots, as Arnaud and Nicole say in a companion text on grammar called, of course, the Port Royal Grammar. But when humans use these noises, they are signifying things at the spiritual level, namely their own ideas. All this is important to the context of logic because the terms used in a proposition signify either things or ideas. For instance, in the statement giraffes are not rocks, the word Giraffes refers to giraffes, the word rocks refers to rocks, and the words are not signify the idea of negation. None of this sounds particularly religious, apart from the use of Augustine. But as it turns out, Arnaud and Nicole wrote yet another work together on the Eucharist, in which they argue that the sacramental host is not just a sign of Christ, as the Protestants claim. That is because in this miracle, the spiritual Christ is actually united to the material body of the bread. This in contrast to the case of human language, where the material noise of words does merely signify a spiritual concept. This brings us to the aspect of the Port Royal logic and may have received the most attention in modern scholarship. It stands to reason that just as words refer to simple concepts or things, so entire sentences should refer to complex ideas. Thus, the sentence a giraffe is in the kitchen would call to mind the idea of a giraffe being in the kitchen. But it needn't do any more than that. One could simply entertain this idea without actually having any opinion as to whether there is in fact a giraffe in the kitchen, or at least so you would think. But the Port Royal Logic seems to take a different view. It apparently claims that the complex idea expressed in a sentence always involves making a judgment. So whenever you think a giraffe is in the kitchen, you have to be asserting that there is a giraffe in the kitchen. This seems to follow from their definition of judgment, which reads in part, judging is the action in which the mind, bringing together different ideas, affirms of one that it is the other, or denies of one that it is the other. The point being that as soon as you have brought together two ideas like giraffe and being in the kitchen, you've already made a judgment that affirms a connection between the two things or denied it. In keeping with this, the text seems to use the terms proposition and judgment as if they were synonymous, because every time you think of a proposition, you are making a judgment. Some interpreters have found it hard to believe that this is what the authors of the logic really want to say, because it causes so many problems. The most obvious is the one I just mentioned. One can understand a certain statement without taking a view on it. Suppose my friends tell me there's a giraffe in the kitchen, and I suspect they're just teasing me. But I'm not sure, because, after all, my door is always open to giraffes, my door is unusually tall. And there are other problems, some of which are More technical. For instance, suppose I'm trying to refute my friends and say if there were a giraffe in the kitchen, I would already hear it making dinner, but I don't hear anything, so there is no giraffe in the kitchen. In this argument we have a so called hypothetical premise where I say what would follow if there were a giraffe in the kitchen. Clearly, when I propose this possibility, I'm not judging that it is true. To the contrary, it's part of an argument designed to show that it is false. Or here's a more straightforward case. If I say my friends must be crazy, they believe there is a giraffe in the kitchen, then I'm using there is a giraffe in the kitchen to express what they are judging, not what I am judging in my own judgment. The most compelling solution is provided by Jennifer Marusi. She suggests that the Port Royal logic means what it says and that it really does equate propositions with judgments. But that is only the most simple case in which we straightforwardly affirm or deny something. In more complicated cases, as when we merely entertain something, propose it hypothetically, or say what someone else thinks, we are actually making a judgment about a judgment. This is clearest in the last example where I say that my crazy friends are making a judgment about a giraffe, which in my view is false, and I myself am making a judgment too, namely that they believe this crazy thing about a giraffe. It works for the other cases too. If I were merely entertaining a proposition, I could be judging that the judgment in question may be either true or false. But I'm always making some judgment or other. As Marusic puts Once one holds that forming a complete thought of the form S is P is a matter of judging that the ideas of S and P agree, it becomes possible to explain other more complex thoughts in terms of the basic case. While this is an interesting philosophical issue in its own right, also historically significant, John Locke seems to have had a similar view. For instance, and more generally, any teaching that could be found in the Port Royal logic was going to find its way to a wide readership. It has been called the most influential general education textbook of the 18th and 19th centuries. It was to give just one striking example, recommended in 1726 by Cotton Mather in colonial Massachusetts, though when I was growing up there in the 1970s and 80s, the text was no longer in vogue and reminded here of the late ancient Platonist Porphyry, who achieved a spectacularly wide readership lasting the better part of a millennium by writing a very short introduction to Aristotle's Logic. As publishers nowadays are well aware, works of individual and idiosyncratic genius are great, but they don't sell nearly as well as a useful textbook. In fact, I can hardly think of a way to communicate philosophical ideas to an even wider audience. Unless one were perhaps to produce a podcast, for example, a podcast that has covered important and influential French thinkers like Descartes, Elizabeth of Bohemia, Gossendi, and Arnault. After which, I guess one would need to move on to the greatest proponent of occasionalism, Nicolas Malabranche. Yeah, someone should really cover him on a podcast. Maybe an occasion will arise next time here on the History of Philosophy without any gaps, Sam.