 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 episode, Seeing is Believing, Nicholas of Autokort's Skeptical Challenge. Is having knowledge more like being pregnant or more like being hungry? What I mean is that pregnancy is an all-or-nothing affair. It's like being alive or being located above the equator, either you are or you aren't. Being hungry, by contrast, admits of degrees taking in everything from Winnie the Pooh's hankering for a little something to the ravenous and permanently unquenched appetite of the cookie monster. If knowing is like this, then you could have more or less certain knowledge of things. You would presumably be prepared to say, for instance, that you know how old you are, but if pushed, you might admit that, though you do know this, you aren't as absolutely certain about it as you are about, say, the fact that 2 plus 2 equals 4. After all, one could devise remotely possible scenarios according to which your actual age is different. Perhaps in your first year of life, you were mixed up with another baby who had a different birthday. Or perhaps your parents are spies who falsified your birth certificate. If you start taking such scenarios really seriously, you might conclude that you don't really know how old you are after all. Then you would be starting to think that knowing is like being pregnant. Real knowledge would have to have the highest degree of certainty, and if this sort of certainty is absent, then knowledge too would be lacking. Often it is the skeptic who insists that knowledge is like this. The philosopher who leaps to mind immediately is Descartes. In his meditations, he famously subjects all his beliefs to rigorous doubt, inspecting them to see whether any of them rise to the level of absolute certainty. But Descartes was not the first to advance such a demanding test for knowledge. It was a challenge already issued by the academic skeptics in antiquity. They took advantage of the Stoics' assumption that knowledge is indeed like pregnancy, an all-or-nothing cognitive state that rules out all possibility of error. In turn, the academics propose that no belief has guaranteed certainty, so by the Stoics' demanding epistemological standards, we should admit that we know nothing, like Socrates did. Though a work by the later ancient skeptic, Sextus Empiricus, was translated into Latin around the turn of the 14th century, it doesn't seem to have had much impact, and we might easily suppose that the religious confidence of the medieval would have prevented them from seriously exploring skepticism anyway. But if we did suppose this, it would be a case where we ourselves fall into error. In fact, a number of 14th century thinkers mounted serious skeptical challenges, albeit without necessarily embracing skepticism in the end. Among them was Nicholas of Otzekor. Born around 1300, he was a contemporary of John Buridan at Paris, lecturing on theology there around the 1330s. He provides us with another entry in our melancholy list of medieval thinkers who were condemned for their teachings. This occurred in 1346, with Nicholas retracting the problematic theses in 1347. It's an interesting and rather ironic case of condemnation. Typically, we assume that philosophers ran into trouble for embracing Aristotelian doctrines too enthusiastically, as with the Parisian masters targeted in 1277. But Nicholas's unacceptable teachings were part of his polemic against Aristotelianism. In the prologue of his late work, Exigit odo Exicucionis, also known as the Universal Treatise, he complained bitterly about scholastic contemporaries who endorsed every claim in Aristotle and of Aries as if it were a self-evident truth. Nicholas sought to undermine these pretensions and in so doing, suggested that almost nothing can be known with certainty. The occasion for this onslaught on scholastic theories of knowledge was an exchange of letters with a certain Bernard of Oretzo. Two of the nine letters Nicholas wrote to Bernard survive. In the first letter, Nicholas is drawing out what he sees as the consequences of Bernard's own ideas about knowledge. These ideas included the now familiar notion of intuitive cognition, the sort of direct apprehension of something that we have in sensation. It is on this basis that we judge whether or not things exist. But Bernard admitted, it could happen that we have an intuitive cognition of something that doesn't exist. What he must have in mind is a scenario like the one that worried Occam. God might create in someone the impression that they are seeing something that isn't there, like by miraculously making me see Groucho Marx standing before me. Occam foresaw the potential of such hypothetical cases to undermine our knowledge, so he insisted that genuinely intuitive cognitions do not give rise to false beliefs. In the scenario just described, if I am really having an intuitive cognition of a non-existent Groucho, that could only mean seeing Groucho while understanding that he is non-existent. Thus, intuitive cognitions are reliable and can still serve as the foundations of all our knowledge. But there's an obvious complaint to be made here, and it duly came from that specialist in complaining about Occam, namely Walter Chatton. Chatton points out that if God wants to, he can create in me the experience of seeing a non-existent Groucho that is just like the impression I would have if I really saw Groucho. So if we admit that such a miraculous event could involve an intuitive cognition, then we have to admit that such cognitions can be misleading after all. All this is the scholastic version of later skeptical puzzles like Descartes' evil demon hypothesis, or more recently, the hypothesis that all of Keanu Reeves' experiences might be a computer-generated alternate reality called the matrix. Since the illusion case is indistinguishable from the case where we are having a normal experience, shouldn't we admit that all our normal experiences are, as far as we know, illusions? We don't have to wait for Descartes or Keanu Reeves to find an affirmative answer to this question. It is precisely what Nicolas Avotacourt says in his letter to Bernard. We cannot infer with certainty that Groucho is really in front of us when we see him unless we assume that our experience is arising normally and not thanks to a supernatural intervention or other deviant source. And, since that assumption is not one we can make with certainty, we cannot ever be certain that what we are seeing is real. Nicolas is not shy in pointing out the pervasive skepticism that is looming here. If intuitive cognitions give us no certainty about the existence of the things they report, then his correspondent Bernard cannot know whether the pope exists or even whether he has a head. Nor could the apostles have been sure that Christ was crucified or rose from the dead. Seeing is believing, but it isn't knowing. Is there anything we could still be certain of in the face of these sweeping skeptical worries? Nicolas addresses himself to this question in a second letter which offers a still more penetrating critique of Aristotelian epistemology. Aristotle and the tradition he inaugurated were committed to what is nowadays called foundationalism, that is the idea that all our knowledge rests on indubitable first principles. This must be so, since otherwise we would always be justifying every proposition we assert with reference to some further proposition and this process would go on indefinitely. Nicolas is ready to admit that there is one principle that is genuinely certain. He formulates it as follows, Contradictories cannot be true at the same time. Thus, while I might not be sure whether Groucho exists, I can at least be sure that Groucho does not both exist and not exist, and that he cannot be both pregnant and not pregnant. The latter would be the better bet here. It's at this point that Nicolas shows himself to be a proponent of the all-or-nothing understanding of certain knowledge. Having granted the absolute certainty of this first principle of reasoning, he says that if anything else is to be genuinely certain, it must have the same status as that principle. Anything less certain than it will fall short of being completely evident. But this is an extraordinarily high standard for certainty. It means, as Nicolas points out, that nothing is certain unless supposing it to be false entails a contradiction. In fact, it might seem that nothing at all could be certain in this sense apart from the very principle that contradictories cannot both be true. However, Nicolas thinks that there may be other truths that are, as he puts it, reduced to this first principle. These would be propositions where the subject and the predicate are somehow really the same. For example, if human is defined as rational animal, it could be completely certain that humans are animals, since to deny this would be to contradict oneself, it would amount to saying that rational animal is not animal. Similarly, Nicolas admits that from the statement, a house exists, one can infer with total certainty that a wall exists since there can be no house without a wall. The catch is that, as we know from the first letter to Bernard, we can never have this level of certainty that any given house exists or that any given human exists. The things we know for sure simply derive from the meanings of the words. They never include anything that could on any scenario, no matter how far-fetched, be false. Nicolas's anti-Aristotelian motives become clearer as he spells out the consequences. For one thing, we cannot be sure that there are substances underlying the accidents of which we are aware. It's natural to assume that there is a substance, namely a human, underlying the sounds and visible shapes we see when we are aware of Groucho, but it is not a straightforward contradiction to suppose that accidents exist in the absence of any substance to which they belong. Here, it may be on Nicolas's mind that accidents do supposedly survive without their original substance in the case of the Eucharist, where the color and taste of bread persist even though the bread has miraculously become the body of Christ. So this is not just a bizarre yet theoretically possible scenario. According to the Christian faith, it actually happens. For another thing, we cannot be sure about necessary causal connections between things. Obviously we are accustomed to expecting that fire will heat things up, but if this should fail to occur, no contradiction would result. Thus our belief that a fire will heat a stone brought near to it falls short of true certainty, the certainty possessed by the first principle about contradictory. The upshot, as Nicolas gleefully remarks, is that all of Aristotle's physics and metaphysics is entirely deprived of certainty. But was Nicolas really seeking to replace the confident convictions of Aristotelian science with thoroughgoing skepticism? Apparently not. At the end of his first letter, Nicolas mentions briefly that in disputations at the Sorbonne in Paris, he has affirmed the evident certainty of the deliverances of the senses and of our own actions. It would have been nice to hear more about this. But it seems at least to show that Nicolas is far from embracing the skeptical implications he has just outlined. His point is rather that Bernard's more traditional scholastic position would lead to those disastrous implications. In fact, when Nicolas was later attacked for his teachings, he did emphasize that everything stated in his letters to Bernard was intended only as a dialectical refutation, not as a statement of his own views. Yet we may still wonder, in the face of his arguments, how could any confidence in our everyday beliefs be restored? One obvious way out would be to reject Nicolas's assumption about the all-or-nothing nature of knowledge and certainty. This is how supporters of Aristotelian orthodoxy responded. One of them, named Master Giles, wrote a letter to Nicolas in which he insisted that certainty does come in degrees. So here we are back to the idea that knowledge is like being hungry in that it admits of more and less. As Giles points out, Aristotle himself said that in a proper demonstration, we should be more confident about our premises than the conclusion since we are trying to reason from what we know better to what is as yet unknown. Yet the conclusion may nonetheless be certain, having been established through this very demonstration. Another more subtle way to reply to Nicolas might be to say that whether one counts oneself as certain depends on context. The standards of certainty appropriate to mathematics are not the same as those appropriate to knowing how old I am. In mathematics, all the certain truths are full-blown logical necessities. It would be unreasonable to demand that our everyday beliefs need to meet that standard. A version of this answer was put forward by John Buridan. He agrees that some principles are certain because denying them would involve embracing a contradiction. These would include such things as saying that human is animal. But not everything of which we are certain has certainty in this strongest degree. When we are doing natural philosophy, we should seek and accept the type of certainty relevant to natural things. This means we are allowed to exclude the occurrence of miraculous examples like the ones that worried Occam and Chatton. Sure, God can make accidents exist with no substance, prevent fire from burning things, or cause something to appear to exist when it does not. But if we are doing natural philosophy, this is irrelevant because the conclusions reached in that context are certain under the proviso that the causes involved are indeed natural, not supernatural. Buridan's solution hearkens back to the stance of Boethius of Dacia, one of the so-called Latin Averroists in the 13th century. He too claimed the right to set aside theological possibilities as long as one is doing physics. Thus, he could show that the world is eternal because no natural motion can arise from nothing, while admitting that this conclusion is overturned once we take into account supernatural creation by God. This sort of response is actually one that Nicholas anticipated himself. He pointed out that certainty about the deliverances of the senses can be secured so long as one assumes that no miracle is taking place, but with his typically demanding approach, added that that assumption is itself uncertain. But I tend to think that Buridan is right. The best way to answer the skeptic is not to show that our knowledge can survive radical scenarios like miracles, evil demons, or the matrix. It is to say that that test is too demanding, and that our beliefs can count as knowledge even if we cannot absolutely rule out the possibility that the beliefs in question are false. Nicholas himself seems to have realized this. In the aforementioned universal treatise, he too lowers the bar for human knowledge, albeit in a different way than Buridan. Here, Nicholas still insists that complete certainty is nearly impossible to achieve. In fact, he even goes so far as to say that the principle about the contradictories, named in his second letter as the sole example of absolute certainty, may not be so certain after all. He imagines someone being habituated to suppose that two contradictory things could both be true. Instead of embracing radical skepticism though, he admits that we may not need absolute certainty anyway. We should instead accept that our grasp of the truth is, as Nicholas puts it, merely probable. This means that we have better reason to affirm the belief than deny it, perhaps much better reason, without being able actually to prove it beyond all possible doubt. The human mind is able to find itself at rest in endorsing such beliefs, confident of being right while still accepting the theoretical possibility of being wrong. But if we are expecting Nicholas to restore the teachings of Aristotelian scholasticism with the sole caveat that they are probable rather than certain, we have another thing coming. We saw other scholastics of this period flirting with the idea that there could be atoms, indivisible components of which perceptible bodies are made. Nicholas doesn't just flirt with this idea, he asks it to come home with him for the night and makes it breakfast in the morning. In themselves, he argues, the components of the universe are eternal. When we seem to see substances being generated and destroyed, in fact we are seeing eternal atoms combining and separating. This revisionary account of physical change goes nicely with his continued doubts about the causes invoked by Aristotelian thinkers. Like Al-Ghazali before him and David Hume after him, Nicholas suggests that experience of the connection between events only yields an expectation that things will be similar in the future. His examples here are well chosen, the way that magnets attract iron and the efficacy of medicine. In these cases, we have no clear understanding of the relation between cause and effect, only a habit of expecting the iron to move towards the magnet and of the disease to be cured. Nicholas of Autocourt was not the only one to voice skeptical ideas around the middle of the 14th century. Similar worries about causation can be found in John of Miracourt, another Parisian thinker who was in fact centred in 1347, the same year that Nicholas was forced to recant his views. For John too, the knowledge that a cause will yield an effect lacks the certainty possessed by a certain first principle. In England, the same sort of ideas were put forth by Robert Holcott, who emphasized the absolute power of God to stop causes from working normally. Even when heat does follow fire, this does not prove that fire caused it any more than the fact that people get afraid in the dark shows that darkness is the cause of fear. More radical still was the Oxford theologian Nicholas Astin. For him, we can never be certain about anything unless it is necessarily true and nothing outside of God is necessary. In theory at least, this banishes all common sense belief from the realm of genuine knowledge. Astin gives some memorable examples, as for instance that there is no outright contradiction involved in the same person being in two places at the same time. If this is possible, then it should also be possible for a person to walk up to another version of himself and cut off his own head. Astin also addressed himself to a question raised by the early medieval theologian Peter Damian, asserting that God can change the past, since no necessary truths would be violated were he to do so. What accounts for this spread of skeptical concerns in the 14th century? The most obvious explanations is that scholastics were impressed by God's power to do anything that is logically possible. With this threat lurking in the background, all knowledge about the created world would seem to be, as it were, marked with an asterisk. It may be true that fire heats, that substances underlie accidents, and that people can't be in more than one place at a time, but all of these truths presuppose that God is not overturning them by performing a miracle. On the other hand, it's not as if God's omnipotence was only discovered in the 14th century. Earlier, medievals likewise held that God can do anything that is logically possible without then engaging in the sort of skeptical worries we've been discussing in this episode. Remember too that Nicholas's skeptical challenge was incited by a more technical and specific doctrine, namely the idea that an intuitive cognition can have a non-existent object. So, while late medieval skepticism did involve allusions to miracles, it may have had its roots more in the epistemology of the time than the fear that the good Christian God sometimes acts like Descartes' evil demon. Still, there's no doubt that Nicholas and other skeptically-minded authors of this period managed a striking anticipation of Descartes and other early modern thinkers. It seems evident, insofar as anything is evident, that this period represents an earlier high-water mark in the history of philosophical skepticism. So I'm sure, insofar as I'm sure of anything, that you'll want to join me for an interview with one of the world's leading experts on medieval skepticism, Dominic Perler. It will be an interview worth waiting for, which is just as well, since it won't appear until mid-September. As usual, I'm having a summer break with a hiatus of one month in both the medieval episodes and the episodes on philosophy in India. Once we get back, we'll be on the home stretch to finish off both of these series. After that, beginning in early 2018, we'll be launching the next two series on Byzantine philosophy and Africana philosophy. So there is certainly plenty to look forward to here on The History of Philosophy Without Any Gaps.