Journal of Didactics of Philosophy 3 (2019) 5 THE APORETIC STRUCTURE OF PHILOSOPHICAL PROBLEMS Wolfgang Barz Goethe-University Frankfurt am Main barz@em.uni-frankfurt.de Received: 1 December 2018 Accepted: 16 January 2019 Abstract The central idea of this essay is that philosophical thinking revolves around aporetic clusters, i.e., sets of individually plausible, but collectively inconsistent propositions. The task of philosophy is to dissolve such clusters, either by showing that the propositions in question, contrary to first impression, are compatible with each other, or by showing that it is permissible to abandon at least one of the propositions involved. This view of philosophical problems not only provides a very good description of well-understood philosophizing, but is also better suited than others to explain some seemingly strange characteristics of philosophy, most notably its armchair character, the large variety of incommensurable doctrines by which it is characterized, and its concern with its own history. Keywords: aporetic cluster, Nicholas Rescher, armchair philosophizing, philosophical disagreement, skepticism 1. Introduction The most important task of those who teach philosophy at colleges and universities is to cultivate passion in their subject. To be in a position to develop a passion for philosophy among students, teachers need to have an answer to the question "What is philosophy good for?"-because nobody wants to study a subject unless it is clear why it is worth pursuing. Thus, the question "What is philosophy good for?" is one of the most pressing questions in the didactics of philosophy. In the absence of an answer, philosophy will appear as an incoherent hotchpotch of conflicting views about all and sundry that have contingently emerged over time, lacking any common objective. As a consequence, studying philosophy will seem to be a pointless and anemic enterprise, repelling those with a sincere desire for knowledge. Thus, it is of the highest importance for teachers of philosophy to be equipped with an adequate explanation as to what philosophy is if we do not want to lose our most talented students to other disciplines. Unfortunately, but predictably, opinions differ widely on the question of what philosophy is all about. According to a view popular among those outside the discipline, philosophy is the study of the written remains of the grand old philosophers, similar to literary studies. While this is not completely false, it is not entirely correct either. Certainly, students of philosophy will spend a lot of time reading and interpreting the written remains of the grand old Journal of Didactics of Philosophy 3 (2019) 6 philosophers. However, doing philosophy is not the same as reading and interpreting texts of other people. Consider the ancient Greeks, who were among the first to practice philosophy: undoubtedly, they did philosophy, but did they study the written remains of still other philosophers? No. How could they? There were no remains of other philosophers to study. If doing philosophy is not the same as reading and interpreting the written remains of the grand old philosophers-what is it then? The answer on which most people inside the discipline would agree is that philosophy is the systematic study of fundamental questions such as "How can we know about the external world?," "What is the relationship between the physical and the mental?," "Do we act freely?," "Where do our moral obligations come from?," "What is a scientific explanation?," and "What makes an object a work of art?," and so on. What, exactly, is the rationale behind these questions? Why are these questions worth raising? And what do we want to find out by addressing them? In my view, the most promising answer is that philosophical questions arise from certain kinds of problems, and by addressing philosophical questions we want to solve these problems. This essay aims to illuminate the kind of problems with which philosophers are concerned. The conception of philosophical problems that I suggest is neither new nor particularly original. It can be found in the works of Plato, Aristotle, and Thomas Aquinas. Descartes, Kant, Hegel, Ryle, and Wittgenstein also hold views similar to the notion presented in this essay. It might even be said that the conception of philosophical problems that I have in mind has been around for as long as people have pursued philosophy. However, it seems to me that it never got the appreciation it deserves. Its central idea is that one should regard a philosophical problem as a particular sort of aporetic cluster, i.e., as "a set of individually plausible propositions which is collectively inconsistent" (Rescher 2001: 5). The task of philosophy is to dissolve such clusters, either by showing that the propositions in question, contrary to first impression, are compatible with each other or by showing that it is permissible to abandon at least one of the propositions involved. This view of the subject matter of philosophy not only provides a very good description of well-understood philosophizing but is also better suited than others to explain some seemingly strange characteristics of philosophy. More importantly, it presents philosophizing as a meaningful and indispensable activity in our intellectual lives. I will develop the said conception of philosophical problems step by step. First, however, I will take a small detour by playing devil's advocate and formulating a thought that is painful for us philosophers: that philosophizing is a hopeless enterprise, an activity not worth pursuing. I will, of course, cast away this tormenting thought as I progress. Nevertheless, it is worthwhile to discuss the rationale on which it is based, for it compels us to elucidate to ourselves and others what we philosophers actually do, and what we want to know or come to know, i.e., what renders philosophy a meaningful intellectual enterprise. Thus, considering the tormenting thought is not an end in itself, but it opens our eyes to the true nature of philosophizing. 2. A Tormenting Thought Debates in contemporary philosophy often unfold according to a depressingly simple script. One day, somebody publishes a paper on a specific topic. This paper is met with broad interest Journal of Didactics of Philosophy 3 (2019) 7 by colleagues, who produce their own papers in response. Journals fill up continually with papers discussing this subject, but views disperse in completely different ways. Fundamental discussions flourish. Conferences are held on the topic. Monographs and anthologies are published, the debate gets more and more technical and detail-oriented, and dissertations systematically explore the topic to its most subtle ramifications. Specialists emerge who are the only ones to keep track of this increasingly differentiated debate, and so on.1 It is certainly not inherently bad that philosophical disputes follow this pattern. What other way is there for an academic debate to unfold? Moreover, the pattern is not peculiar to philosophy. Other academic disciplines develop their debates in similar ways. Nevertheless, there is something disturbing about this. From time to time, I cannot help feeling alienated by the fact that philosophical debates always follow the same old formula (and I hope some of my colleagues feel the same way). When that happens, I am tempted by the tormenting thought that the activity I usually practice with devotion and joy- philosophizing-is ultimately a worthless endeavor. Certainly, philosophy enjoys a very good reputation due to its venerable past. Surely, we are paid well for what we do. Publishers print our books and papers, and there is no lack of public recognition. Still, is it not possible that we, philosophers, are all caught in a collective self-deception? Is it not possible that philosophy, despite our outward pretense, is not a discipline that aims at knowledge and truth? Is it not possible that everything we do is pseudo-scientific shadowboxing, quite amusing as entertainment but in no way deserving the title it claims for itself, "love of wisdom"? This tormenting thought might seem as though it were concocted from thin air. However, one can indeed find reasons to believe it is true. Specifically, I would like to discuss three allegations that are repeatedly made against philosophy. The first accuses it of being an armchair discipline. Most of us would agree that philosophy is an a priori activity. It does not require laboratories, experiments, or scientific field research yielding empirical data. The work of the philosopher is simply to think. The opponent might argue that this is not a sufficient certificate of quality regarding a discipline that claims to generate deep truths about man's place in nature, the limits of our knowledge, or the relationship between mind and body. On the contrary, philosophy's armchair character proves that philosophers produce nothing but mere conjectures reflecting their own prejudices. The second allegation supporting the tormenting thought criticizes philosophy for not generating any progress. Philosophy is characterized by a large variety of incommensurable doctrines whose proponents are caught up in everlasting disputes. This stands in vast contrast to the natural sciences, where, after a period of competition, one theory establishes itself as universally accepted. There is not the slightest prospect that this will also happen one day in philosophy. The opponent might argue that this proves that philosophers desperately seek to provide answers to questions that do not actually have answers, ultimately rendering those questions meaningless. Thus, if there is any role of philosophy, it is surely not to yield knowledge about man and the world but to create confusion. The third allegation might be the most agonizing. It denounces philosophy as being pathologically obsessed with its past. "A science which hesitates to forget its founders is lost," 1 I borrow here from Andreas Kemmerling's apt depiction in Kemmerling 2017: 568. Journal of Didactics of Philosophy 3 (2019) 8 Whitehead once said (1929: 107). Philosophy has never forgotten its founders. On the contrary, it seems to obsess over analyzing long-gone thinkers. This is precisely what provides the opponent with a target to discredit philosophy yet again. There is not a single other discipline that lavishes so much care and attention on the doctrines of its old masters like philosophy does. In this regard, philosophy resembles religion more than science. Philosophers must face these three allegations time and again, and they fuel the tormenting thought that philosophy might be nothing but sophisticated nonsense. I admit that I experience moments of weakness in which I am sensitive to this thought, but in the end, I am convinced that we should face it most resolutely. However, there are different approaches to opposing this thought, and some are better suited to defend philosophy against its detractors than others. To support the strengths of the strategy which I prefer, first I would like to outline some alternatives that I do not consider particularly promising. The first strategy is simply to ignore the allegations that lead to the tormenting thought. This strategy rests on philosophy being a well-established academic discipline that is currently flourishing like never before. Philosophers are well-liked in public opinion, at least in Germany. Some of our colleagues' books-even if we might not appreciate their work-have made it on the bestseller list. We even get our own TV shows! Why, then, should we care about the tormenting thought? I might take the tormenting thought too seriously, but this strategy seems too easy. Even though we might consider it to be ridiculous, the tormenting thought should give us pause. Another strategy seeks refuge in appeasing those who despise philosophy. "There is something to your allegations," one might say. "The way we pursued philosophy in the past and still pursue it today is problematic, so we should change that." There are several suggestions on how to change our practice accordingly. The first is already somewhat out of fashion. It recommends practicing rigid self-restraint in choosing our subjects and research methods. The participants in the Vienna Circle-although they are not the only ones- followed this approach, advising philosophers to practice only logic of science. A second example is Edmund Husserl. One could understand Husserl's phenomenology, with all its methodological precautions and safety measures (keyword: phenomenological reduction), as another program of philosophical self-restraint, enabling philosophy to progress and therefore ending all the quarrels that damage its reputation. Even though phenomenology and logical empiricism have nothing in common in terms of content, they do seem similar in metaphilosophical respects. Specifically, both hope that the adaptation of their program will free philosophy from the scandal of conflicting schools. A second suggestion regarding how we should change our ways of practicing philosophy is that we leave our convenient armchair and take empirical action. We should at least collaborate with natural scientists. (It seems that this is the favorite suggestion of educationalpolicy makers and science managers, often embellished with the notion of "interdisciplinary research.") This suggestion culminates in the emergence of experimental philosophy, which is on everyone's lips today. One more proposal for changing philosophical practice-which responds to the claim that philosophy focuses too strongly on its own history-suggests disparaging the study of longgone philosophers' writings. Gilbert Harman provided us with a good example when he affixed a note to his office door in Princeton. The note was jokingly based on a slogan by Journal of Didactics of Philosophy 3 (2019) 9 Nancy Reagan. Instead of "Just say no to drugs!" it read "Just say no to the history of philosophy!" While Harman himself might have had a more subtle view on the subject (see Sorrell and Rogers 2005: 43-44), the message seemed quite clear: well-understood philosophy does not deal with its own history. Plato, Aristotle, Descartes, or Kant might be mentioned in an overview of the history of philosophy. However, if one wants to become a philosopher, the thoughts of those thinkers can be safely ignored. If one wants to become a chemist, it is likewise not necessary-and is even harmful-to study the writings of the alchemists. None of these strategies is suitable to defend philosophy against its detractors. On the contrary, they pave the way for its downfall. First, philosophy lives on the diversity of contradictory positions. To take disciplinary action against this diversity would be poisonous for philosophical research. These aspirations aim at an idea of progress that simply does not work for philosophy. Second, it is essential for well-understood philosophizing to be pursued from the armchair. We do not have to be ashamed of that. All proposals that aim to make philosophy empirical simply do not understand what philosophy is about. Finally, philosophical debates are dependent on conversations with the dead. Thus, philosophers cannot simply ignore the history of their discipline. If they did, they would rob themselves of their most important sparring partners. Presently, the preceding statements are no more than confessions of faith. However, I hope that I can render them plausible in the discussion that follows. The core of my strategy consists in converting the allegations against philosophy into requirements that wellunderstood philosophizing must fulfill. Thus, to keep the detractors in their place, we need a metaphilosophical theory that explains (i) why philosophy must be practiced in the armchair, (ii) why it is characterized by a variety of opinions, and (iii) why its own history plays an indispensable role in the discipline. 3. Aporetic Clusters as Epicenters of Philosophical Deliberation The metaphilosophical approach I would like to present in this section draws heavily on ideas by Nicholas Rescher (1985), who himself refers to Nicolai Hartmann (1949).2 The main idea 2 An anonymous referee has suggested that the recent discussion between Peter Hacker (2009) and Timothy Williamson (2007) on the question of whether and how philosophy is to be understood as an armchair discipline might also be relevant for this paper's topic. However, it seems to me that the discussion between Hacker and Williamson mainly revolves around the question of whether philosophy is concerned with concepts rather than things themselves. In short, Williamson says that philosophy is concerned with things, not concepts (and thus more akin to natural science than many philosophers are inclined to think), whereas Hacker says that "being concerned with concepts" and "being concerned with things" are not mutually exclusive options. Philosophy, according to Hacker, is concerned with things by means of analyzing concepts. As far as I can see, neither Hacker nor Williamson, in their discussion, touches on the question of the nature of the problems from which philosophical thinking arise. Note, however, that Hacker gave a brief explanation of philosophical problems a few years before his quarrel with Williamson in "Verstehen wollen" (2001). There, Hacker says that philosophical problems arise out of conceptual unclarity and confusion, which, in turn, arise from our lack of overview of a concept. Although I am sympathetic to many things Hacker has to say about philosophical methodology, I disagree on this point. As will become clear in a moment, my view is that philosophical problems do not arise due to a cognitive flaw for which we are responsible ("lack of overview"), but due to an inconsistency between fundamental elements of our conceptual scheme. This inconsistency is not a mere impression that results from our being confused (and thus might be eradicated by unraveling our confusion), but it is real (and thus can only be eradicated by revising certain fundamental elements of our conceptual scheme). Journal of Didactics of Philosophy 3 (2019) 10 is that philosophical deliberation centers around so-called aporetic clusters. The concept of an aporetic cluster refers to a set of propositions that seem plausible individually but cannot be true collectively. Aporetic clusters are nothing unusual. We encounter them in our daily lives as well as in the empirical sciences every time two well-reasoned, but incompatible opinions collide. Thus, not every aporetic cluster brings philosophy on to the scene. To become the subject of philosophical research, an aporetic cluster must be of a particular kind. The special characteristic of aporetic clusters central to philosophical thought is that they cannot be solved by means of empirical research.3 This is because their conflicting propositions put very general, fundamental, deeply rooted intuitions into words. Even though those propositions are not analytically true, they enjoy a state of empirical untouchability nonetheless. The distinctive character of aporetic clusters significant to philosophical thought is best explained by using an example. Thus, let us examine the aporetic cluster that underlies epistemological skepticism.4 The modern version of this problem revolves around the notion that I am in the clutches of a mad scientist who has destroyed every part of my body with the exception of my brain, which he keeps in a vat filled with nutrient solution. As if that is not perfidious enough, we shall also imagine that the mad scientist supplies my brain with electric impulses that lead me to have sensual experiences indistinguishable from those I would have had if I had not been kidnapped. Although it seems to me that I am sitting at my desk right now, I (or what is left of me) am actually in the laboratory of the mad scientist in, say, Silicon Valley. If this version of the problem is taken as a basis, the aporetic cluster consists of the following sentences: (1) If I know that I am sitting at my desk right now, then I also know that I am not a brain in a vat right now. (2) I do not know that I am not a brain in a vat right now. (3) I know that I am sitting at my desk right now. These three propositions are quite complex, both grammatically and semantically. Therefore, it might not be initially obvious as to why they are incompatible, in the characteristic sense of an aporetic cluster. Thus, let us look at the sentences' propositional logic: 3 It might be objected that not being solvable by means of empirical research might be necessary, but surely is not sufficient for being an aporetic cluster central to philosophical thought since some mathematical problems can be formulated as aporetic clusters as well. There is a more and a less concessive response to this concern. The more concessive response would be to say that there are no strict boundaries between philosophy and mathematics: there is a twilight-zone of problems that are both mathematical and philosophical. The less concessive response is that aporetic clusters central to philosophical thought have the distinctive feature of incorporating propositions that revolve around notions being of high significance for human life. I tend towards the non-concessive answer. At the same time, I frankly concede that I cannot provide a clear-cut definition of "being of high significance for human life." I thank an anonymous referee for raising this point. 4 Another paradigm example is the mind-body problem, which is characterized by the following propositions: (1) Mental phenomena are not physical. (2) Mental phenomena can cause physical phenomena. (3) Physical phenomena have physical causes only. (See Bieri 1981: 5; see also Lepore and Loewer 1987: 630. Additional examples can be found in Rescher 1985). Journal of Didactics of Philosophy 3 (2019) 11 (1) p → q (2) ¬q (3) p The lowercase "p" stands for "I know that I am sitting at my desk right now," while "q" is the abbreviation for "I know that I am not a brain in a vat right now." It is easy to see the incompatibility of these three propositions now. Propositions (1) and (2) logically imply the negation of (3): ¬p. Moreover, (2) and (3) logically imply the negation of (1): ¬ (p → q). Finally, (1) and (3) logically imply the negation of (2): q. As much as we might wish to keep all three propositions, we cannot adhere to all of them. If we want to be rational-as we should be-we must relinquish at least one of the three propositions. However (and this creates a sticky situation), all our options are equally unappealing because every single one of these propositions, taken on its own, has a significant degree of persuasive power. First, let us take a closer look at proposition (3), "I know that I am sitting at my desk right now." The reasons why this is true are simply overwhelming. In fact, they are so overwhelming that it seems ridiculous even trying to deny (3), at least if one is guided by common sense and not already philosophically biased in some way or other. (I will go into more detail about this restriction in a moment.) What about proposition (2), "I do not know that I am not a brain in a vat right now"? This, too, seems undoubtedly true. The brain in a vat scenario is conceived in such a way that nobody can rule it out. The sense experiences I would have as a brain in a vat would not differ at all from those I actually have. Therefore, whether I am in a skeptical scenario cannot be judged from my perspective. There is neither a tangible sign telling me that I am, nor is there one appeasing me that I am not, in the hands of a mad scientist. However, unless our experiences provide evidence to the effect that I am not a brain in a vat, I cannot know that I am not a brain in a vat. (Just as with proposition (3), this reasoning will not be the final, but merely a preliminary evaluation of the plausibility of (2).) Finally, what about proposition (1), "If I know that I am sitting at my desk right now, then I also know that I am not a brain in a vat right now"? Those who are familiar with epistemology might have realized that (1) is an instance of a general maxim commonly called the principle of closure. Formulated crudely, it states that if a person S knows p, and p logically or conceptually entails q, then S knows q as well. Phrased this way, the principle of closure is surely wrong since there are a lot of situations where we do not know everything a particular known proposition entails logically or conceptually. For instance, just think of examples from the field of mathematics. Thus, one should formulate the principle more carefully, like this: "If a person S knows p and comes to believe q by correctly deducing q from p, then S knows q." This is the so-called principle of closure under known entailment. It seems highly plausible since it describes a natural, familiar intuition that we all have. Many epistemologists even think it would be crazy to abandon it (cf. BonJour 1987; DeRose 1995; Feldman 1995).5 5 If we want to take into account the principle of closure under known entailment, we should phrase propositions Journal of Didactics of Philosophy 3 (2019) 12 In summary, propositions (1), (2), and (3) are not just incompatible. Seen individually, each has a significant degree of persuasive power. Thus, we face a trilemma: if we want to be rational, we must surrender at least one of the three propositions. However, no matter which proposition we choose, we will always repudiate something we find true at the bottom of our hearts. At this point, I will probably be met with strong resistance. "Propositions (1), (2), and (3)," some will hold against me, "are not at all equally plausible!" Someone under the influence of Fred Dretske (1970) or Robert Nozick (1981) will find proposition (1) less plausible than (2) and (3). Those who have read Austin's "Other Minds" (1961) or studied Moore's proof of the external world (Moore 1959) may find (2) less plausible than (1) and (3). Finally, a convinced subjective idealist of the likes of Berkeley might find (3) less plausible than (1) and (2). However, this does not mean that we are not facing a genuine aporia, but that we must adopt a certain attitude to recognize it: we must block out our entire laboriously-earned philosophical expertise. If one judges right from the outset that the principle of closure is implausible anyway because one believes everything Dretske and Nozick argue, then there is no problem. One is, so to speak, epistemologically at peace with the world. Similarly, if one would say, "It is obvious that I cannot know anything about the external world. Everything I can know is about me and my own consciousness," then the aporia will not be visible for him or her. One is then in a state of theoretical bliss, which is fine. However, being in a state of bliss, one will not find access to philosophy, which requires an intellectual uneasiness resulting from a certain kind of theoretical humility, austerity, or naiveté, if one will. One must parenthesize one's philosophical expertise to recognize a philosophical problem as a problem. Those who look at the world through specific philosophically-charged glasses are liable to be blind to philosophical problems. This is precisely where perhaps the greatest challenge of philosophical didactics lies: opening the eyes of those who study philosophy so they may become aware of philosophical problems. This is only possible when philosophy teachers restore the philosophical innocence of their students-which may lead to paradoxical situations. On the one hand, our didactical aim is to give our students an understanding of Dretske's and Nozick's arguments against closure. We want them to know how Moore, Austin, and other proponents of ordinary language philosophy argue against the skeptic, and also how subjective idealism works. On the other hand, if we want them to recognize philosophical problems for what they are, we must pretend as if these theories, systems, and arguments do not exist. Thus, making philosophical problems visible is such a strenuous effort that teaching philosophical doctrines seems like child's play in comparison.6 (1) and (3) differently. We should add a clause along the lines of: "I believe that I am not a brain in a vat because I know that someone who sits at his desk cannot be a brain in a vat." To keep the problem simple and clear, I will do without this modifier. 6 See Meyer et al. (2018) for a promising suggestion on how to make philosophical problems visible in high school philosophy classes. The aim of the "Strukturmodell" is to provide the teacher with techniques to animate pupils to detect dissonances in their belief system and thus to reveal the philosophical puzzles dealt with in the class. Thus, Meyer et al.'s "Strukturmodell" could be regarded as a concrete implementation of the more abstract ideas presented in this paper. Thanks to an anonymous referee for drawing my attention to the "Strukturmodell." Journal of Didactics of Philosophy 3 (2019) 13 Quite frequently, students are already married to a certain philosophical doctrine. This poses a very special didactic challenge. Adherents of subjective idealism, constructivism, and relativism are good examples because these philosophemes are very popular, especially with first-year students. Due to their theoretical bias, these students are unable to recognize the scandalous nature of external world skepticism because they consider themselves to be in the matrix, anyway. They will also not understand the point of large-scale damage limitation exercises such as Kant's transcendental idealism. The main task of the teacher, then, is to bring such students back down to earth, for philosophical problems are recognizable as problems only from this point of view.7 After this slight digression, let us return to the characterization of aporetic clusters central to philosophical thought. Not only are propositions (1), (2), and (3) incompatible, even though they seem equally plausible to us (in a state of philosophical innocence), but to make things worse, we cannot delegate the decision regarding which proposition should be dismissed to the empirical sciences. Our reason is on its own with this decision. To illustrate this point, consider an empirical research project that aims to falsify the principle of closure under known entailment. What might the framework of such a research project look like? One might say, "That is fairly simple. One analyzes a sufficiently large group of people who know p and believe q because they know that p entails q. Then, one checks if all these people also know q. If there are some who, under the described circumstances, do not know q, then we have proved the principle of closure under known entailment wrong." The problem with this is that we cannot determine that a person does not know q under the described circumstances without already giving up the principle we want to falsify, since the principle warrants that every person knows q under the described circumstances. In other words, we can only disprove the principle if we presume that it is wrong. Surely that is no empirical research project worth funding. At this point in dialectics, philosophers enter the arena equipped with an arsenal of nonempirical means to solve the problem. It is not clear from the outset what the exact means are. Some hold conceptual analysis and logical reconstruction in high esteem, while others prefer thought experiments and counterfactual deliberations. Still others try to identify and question specific background assumptions that feed into the formulation of the problem. There are virtually no limits to methodic imagination in philosophy. Everything is permissible if it serves to achieve the goal of solving or dissolving the initial problem.8 4. The Explananda Explained Regarding philosophy as a reaction to aporetic clusters allows us to refute the allegations I described at the beginning of this essay. We are now able to explain why philosophy must be done from the armchair, why the diversity of opinions in philosophy is principally irreducible, and why philosophy's own past is so important to the discipline. 7 In order to forestall possible misunderstandings, please note that I do not recommend confronting students with philosophical problems without teaching how to resolve them. I merely emphasize the significance of making philosophical problems visible before teaching how to resolve them. 8 One might ask, "Even empirical means?" Yes, of course! If the problem turns out to be solvable through empirical research, it simply did not belong to the class of genuinely philosophical problems. Journal of Didactics of Philosophy 3 (2019) 14 We can quickly deal with the first point-characterizing philosophy as an armchair discipline. Philosophy must be practiced in the armchair because the aporetic clusters with which philosophers deal cannot be solved by empirical means. The second point-the irreducible diversity of opinions-requires a more comprehensive explanation. We cannot principally reduce the diversity of opinions, because there will always be a plurality of options to solve or dissolve an aporetic cluster and different people will have different opinions on the question of which option is best. Let us look at the problem of skepticism again. There are at least three options: dismiss proposition (1) and keep (2) and (3), dismiss (2) and keep (1) and (3), or dismiss (3) and keep (1) and (2). All these options have found supporters throughout the history of philosophy. As mentioned before, Fred Dretske and Robert Nozick sacrifice the principle of closure and thus dispatch proposition (1). This way, they can adhere to (2) and (3). In contrast, Austin and Moore sacrifice the second proposition to save (1) and (3). Additionally, subjective idealists suspend the third proposition and are thus able to sustain (1) and (2). There are certainly other solutions, as well. One is to argue that (1), (2), and (3) are actually quite compatible. This is the position of contextualism. Contextualists claim that the verb "to know" assumes different meanings within the three propositions. Thus, they claim that it is incorrect to represent (1), (2), and (3) as I did above, by "p → q," "¬q," and "p," respectively. In fact, contextualists claim there is no inconsistency in the conjunction of (1), (2), and (3) (cf. DeRose 1995). I will not discuss these suggestions in detail. The point of reviewing the multiplicity of philosophical approaches to skepticism is merely to emphasize that aporetic clusters central to philosophical thought always leave room for more than one solution-at least if you look at them open-mindedly. Moreover, proponents of each of the suggested solutions can provide good reasons for their preferred option: Austin, Berkeley, DeRose, Dretske, Moore, Nozick, and others did not randomly choose an option, but made every effort to support their position with reasons-they argued for their preferred option, and they argued very well. Thus, it seems that all options are equally reasonable. Unlike empirical problems, philosophical problems do not appear to have a "correct" solution that will ultimately prevail. At this point, a difficulty may suggest itself. If all options were equally reasonable, and there was no better or worse, then philosophy, understood as the struggle to solve aporetic clusters were entirely pointless. Why should one argue for a specific solution if it is clear in advance that it will not be better than the solutions suggested by one's philosophical rivals? If there is no better or worse, why quarrel with others about the best way to solve a philosophical problem? Doesn't the claim that all solutions are equally reasonable amount to the claim that philosophical puzzles are unsolvable in the end? If philosophical puzzles are unsolvable, we could spare ourselves the effort of trying to solve them.9 I would like to mitigate these concerns by drawing an analogy to politics. Consider political battles in democracies. Conservatives and social democrats, say, share the aim of promoting the well-being of the whole society. However, they differ over the question of how to achieve it. For example, conservatives advocate reducing taxes in order to keep the economy growing, while social democrats champion a moderate increase in taxes in order to 9 I owe this objection to two anonymous referees. I thank them for pressing me on this point. Journal of Didactics of Philosophy 3 (2019) 15 redistribute money to the poor. Both sides have good arguments for their cause. Moreover, there is no neutral vantage point for assessing which option is more reasonable than the other. (Surely, there are those economists who pretend to be the voice of reason, but closer attention reveals that even the most "neutral" economist is already driven by political motives.) Thus, in a sense, there is no better or worse: there is no independent, presuppositionless measure by which it could be determined whether reducing taxes is more reasonable than increasing taxes relative to the overall aim of promoting the well-being of the whole society. However, in another sense, there is a better and a worse. Regarding politics, at least regarding "big" political issues such as taxation, no one can adopt the stance of a disinterested observer-for each of us occupies a specific position, plays a certain role in society which goes along with particular needs and wants that, in turn, impose certain political norms and values on us. (If you are a well-paid CEO you typically hold other things in high regard than someone who is unemployed.) Thus, we cannot help looking at political issues from a prejudiced perspective, a perspective that suggests a certain political action as the most reasonable. So even if there is no independent measure to use to decide which action is most reasonable, political disputes over the issue of which action should be taken do not become pointless. Something along these lines is true of philosophy as well. There is no neutral vantage point for assessing which of the possible solutions to an aporetic cluster is the most reasonable solution. In this sense, there is no better or worse. However, each of us comes already equipped with certain cognitive norms and values: for example, some are drawn to simplicity, hold empirical adequacy in high regard, and have confidence in common sense, whereas others attach greater importance to originality, theoretical elegance, and wideness of scope.10 Thus, we cannot help looking at philosophical puzzles from a prejudiced perspective, a perspective that suggests a certain solution as most reasonable.11 For example, if you have confidence in common sense, you will find subjective idealism repellent. In contrast, if you are deeply suspicious of common sense, you may find subjective idealism attractive. In this sense, there is a better and a worse. A dispassionate stance towards the multiplicity of incompatible solutions to a philosophical puzzle is quite impossible. From our standpoint, the solutions preferred by our philosophical rivals seem utterly unreasonable. Thus, even if there is no independent measure to use to decide which solution is most reasonable, philosophical disputes over the issue of which solution should be preferred do not become pointless. By the same token, it is quite impossible to reach an agreement: since subjective differences in ranking and applying cognitive norms and values are pervasive, different people tend to prefer different solutions to one and the same aporetic cluster. To enforce an agreement (by whatever means) would run counter to human nature. 10 Other examples of cognitive (or, as they are sometimes called: epistemic) values include coherence with other accepted theories, completeness, internal consistency, explanatory power, precision, and predictive accuracy. Cognitive values also manifest themselves in our judgments about what is, relative to a certain issue, significant or unimportant, obvious or far-fetched, and so on. For more on cognitive values, see Rescher 1985, chap. 6. The locus classicus on cognitive values and their role in theory assessment is Kuhn 1977. 11 Thus, the stance, described above, that should be adopted in order to recognize philosophical problems for what they are is highly artificial. It requires much effort: not only bracketing one's philosophical background knowledge but also restraining one's cognitive temperament, so to speak. Journal of Didactics of Philosophy 3 (2019) 16 It might be objected that this diagnosis vitiates philosophy even more. If philosophical disagreement about the "correct" solution of an aporetic cluster stems from differences in cognitive norms and values, then arguing for a specific solution would be entirely pointless. Preferring one over another solution would be just a matter of taste, not open to rational assessment. However, this objection confuses norms and values with mere preferences. Norms and values are not mere preferences. Whereas mere preferences cannot be rationally assessed, norms and values can be. The question "Is it rational to prefer coffee over tea?" does not make sense. However, the question "Is it rational to have confidence in common sense?" does make sense. Moreover, preferences are not judgment-sensitive, whereas norms and values are: thinking thoroughly about common sense may change my attitude towards it. However, thinking thoroughly about the taste of coffee does not change my preference for (or aversion to) coffee. Thus, arguing for a specific solution to an aporetic cluster is not pointless at all, because our preference for a specific solution is not a blind reflex, determined by factors that are rationally impenetrable, but is a reason-driven decision, determined by factors that are themselves open to rational assessment (cf. Rescher 1985: 145-151). Allow me to add a didactic corollary. Here lies a profound challenge of philosophical didactics: to convey the idea that there is no neutral vantage point for assessing which of the possible solutions to a philosophical puzzle is the most reasonable, and at the same time to encourage students to systematically think about which of the possible solutions is the most reasonable. Again, there is something paradoxical about it. On the one hand, we want students to develop (and defend) a well-justified view on the question of which solution to a philosophical puzzle is the best. On the other hand, we want our students to remain openminded and sensitive to the thought that their preferred view-even if brilliantly argued- might not be the last word on the issue. The ideal student of philosophy unwaveringly follows the voice of reason, but at the same time wonders whether it leads to the right way. Probably the best a teacher can do to achieve this ideal is to promote intellectual integrity: encourage students to put up a bitter resistance to philosophical views that seem unreasonable to them after carefully weighing all the pros and cons, but at the same time admonish them to be prepared to convert as soon as the rival's argument seems cogent. One gets the impression that the attitude described has a poor reputation in public opinion (even though, in driveling speeches, one frequently hears speakers pay lip service to it). Public opinion generally prefers people who rigidly stick to their views, once formed, throughout their life (as if persistence was an intrinsic value). Thus, in philosophy classes, it is important to lead by example: do not pretend to know it all, but be self-critical, admit errors on your side. Moreover, familiarize students with intellectual biographies such as that of Ludwig Wittgenstein, Laurence BonJour, or Frank Jackson (to cite just a few), who, at some time or other in their career, rebelled against views they formerly held or even converted to views they once had fought against. Let me end by adding a few remarks about the relation between philosophy and its history. Philosophy is so concerned with its own history because both formulating (or should I say: discovering?) an aporetic cluster and exploring its various solutions is an utterly lengthy process. The timeframe in which these processes take place is neither comparable to a talk show nor a term of office. Usually, it takes decades to centuries to fully develop a particular solution to an aporetic cluster. There is no single person who can accomplish this task in his Journal of Didactics of Philosophy 3 (2019) 17 or her limited lifetime. Thus, we must regard philosophy as a conversation spanning over centuries, as an intergenerational enterprise for which the thoughts of philosophers who lived hundreds of years ago are still systematically relevant. The idea of ahistorical philosophizing fails to recognize this. If we did not care about the thoughts of our ancestors, we would cut off important conversational threads and would thus be unable to run through ideas that might just be emerging. Ultimately, there is no reason to despair of philosophy. The discipline might have its oddities, but they are due to the nature of the problems with which philosophy is concerned. 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How to cite this article Barz, Wolfgang (2019), "The Aporetic Structure of Philosophical Problems," Journal of Didactics of Philosophy 3(1): 5-18. URL: www.philosophie.ch/jdph.