An Introduction to Dialectical Logic: The Recovery of Probable Certainty as the Labor of the Human Intellect

Recently, I ran an eight week seminar (for the Lyceum Institute) on the nature of dialectical logic in the philosophical tradition downstream from Aristotle (though with various contributions from later classical and medieval sources). The course was primarily propaedeutic, an attempt to lay the groundwork for later, more detailed engagement with the Topics of Aristotle and its reception. Our approach was therefore somewhat “guided” from the outside, following above all the work of Yvan Pelletier, along with the writings of Dominican Fathers Ambroise Gardeil and Timothée Richard. In these authors (above all, Pelletier), we found remarkably able guides for situating dialectical logic among the disciplines of so-called “material logic.” All of us in the seminar came away surprised at how much this engagement changed our outlooks concerning both noetics in general and logic specifically. In the present essay, I wish simply to present some synthetic reflections based upon our reading and discussion. At the end of this text, I will include a bibliography of the works we gathered for the reader’s further consideration.

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It is an often-told tale: modern epistemology vacillates between a haunting desire for clear and demonstrative certainty, on the one hand, and a kind of mere statistical probabilism or even pragmatism, on the other. I am generally averse to grand narratives, for they risk distorting history for ideological ends. Too often they carry the undertone of an insider’s story about reality, a narrative that claims to unveil the “real” causal links of history and humanity, enabling those “in the know” to look with some scorn upon those who supposedly do not understand how things truly are constituted (the “real story”). My own diagnosis of this epistemic vacillation must therefore be taken as expressing only one part of what is likely a more complex truth; nonetheless, I believe it has genuine explanatory force for at least part of this oft-recounted tale.

We all stand downstream of Aristotle’s Organon. It is not for nothing that he believed himself to be inventing the science of logic (though, we must admit, he drew upon a broad experiential basis formed during his years in the Platonic Academy). The structure of formal and material logic—even in its more mathematicized modern forms—remains downstream of the Aristotelian investigations into the “instrument” of reason.

Within the reception of these logical works, there is some variation regarding the canon. The strictly peripatetic account includes the Categories, On Interpretation, Prior and Posterior Analytics, Topics, and Sophistical Refutations. The Arab-language scholastic tradition (followed by a number of Latin scholastics, including Thomas Aquinas) also placed the Rhetoric and the Poetics within the logical corpus. Among these works, the Rhetoric, Topics, Posterior Analytics, and Sophistical Refutations gradually came to be understood as forms of “material logic,” investigating logical relations precisely in view of the material content of reasoning.

It is not surprising, then, that this tradition developed a marked tendency to emphasize “scientific” knowledge—the epistēmē treated in the Posterior Analytics. This logical form came to be regarded as demonstration in the strict sense. Demonstration required an ultimate foundation upon per se nota (immediately known) truths, reasoning through necessary connections between subject and predicate (with middle terms properly defined for such connections), above all in the form of per se explanatory causal argumentation (propter quid). We might say that this is the “gold standard” of human reasoning, and indeed it provides the etymological root of the modern discipline of “epistemology.”

Once, in a public lecture, the very able scholar of Arab-language scholasticism, Dr. Thérèse Druart, emphasized that the Latin schoolmen inherited from their Arab-language interlocutors a kind of obsession with demonstrative science. Even if one wishes to challenge this claim as overly-sweeping, I think there is something to it. One need only consider Ibn-Rushd’s (Averroes’s) Decisive Treatise Determining the Nature of the Connection between Religion and Philosophy, written against his fellow Muslims who were “theologians.” In that work, he places philosophical demonstration at the pinnacle of intellectual achievement and relegates the religious disputation of his contemporaries to the dustbin of merely probabilistic dialectics—clearly with the aim of discrediting their positions and placing them under the judgment of the philosophers, who alone, he claims, possess the capacity to evaluate matters according to their “necessary reasons.” (From what I recall, Dr. Druart attributed this emphasis on demonstration, at least in part, to the much earlier influence of al-Fārābī on the various later Islamic scholastics.)

Whatever the precise genealogy, Averroes’s stance is structured upon a particular understanding of the tasks of logic within the Aristotelian schema. The “Commentator” (as he was called in the Latin Middle Ages) devoted considerable effort to commenting on Aristotle’s Topics, the treatise dedicated to dialectical or probable reasoning. Thus, probable reasoning certainly has a place—but it is non-demonstrative and, ultimately, of second order and second class.

Granted, Aristotle is quite insistent on the variability among the sciences themselves, and this is how he was generally received by his later scholastic interpreters as they unfolded their detailed appropriations of the Posterior Analytics. This sensitivity helped to prevent a complete mathematicization of scientific certainty in this tradition. (The meeting of Aristotelian demonstration and neo-Pythagoreanism in the early modern period would change this trajectory, however, in ways that remain with us to this day.) There are different kinds of certainty, yet wherever the requisite conditions are met, science / episteme remains possible. It is, for Aristotle too, the “gold standard.”

In comparison with such demonstrative knowledge, merely probable premises and conclusions can appear pale. It is all too easy to say, “Well, then, you can only get probable conclusions out of probable premises, even if you employ certain common logical principles.” Probability thus seems an embarrassing lack of certainty—a failure of reasoning, a halfway-house for those unable to complete the full journey of speculative cognition. Indeed, modernity will be haunted by the desire to make every science as certain as geometry, such that genuine knowledge must, de iure, proceed more geometrico, according to the geometric mode of demonstration.

And, in modern Catholic thought, the emergence of probabilist casuistry was a symptom of broader shifts in the understanding of probability itself. Whether or not this development was directly connected to the rise of the modern mathematical notion of probability, the moral-theological understanding of probable certainty gradually came to signify not a position supported by real reasons—strong enough to outweigh competing positions, though not demonstrative—but rather any opposition that appeared “colorable,” one among several stances each possessing some degree of “probability.” At best, the notion of probability was reduced to a kind of more-or-less grounded suspicion. Depending on one’s casuistic school (probabilist, equiprobabilist, probabiliorist, tutiorist), different interpretive canons were formulated for adjudicating moral choices. Yet, as will be discussed below, within this schema the notion of probability was largely evacuated—except among the “probabiliorists,” who, despite the significant limitations of the casuist approach, retained the classical idea of probable certainty as a genuine inclination of the mind to assent to one position over all others, even if some “fear of error” remained. Otherwise, probability lost its gravitational pull toward truth and became merely the label for positions that could be tallied side by side, each possessing a kind of “probability,” as we say in colloquial speech.

Now, in moral matters, the situation is uniquely complex, owing to the importance of virtue (and thus rectified appetite) in the exercise of prudence and in the distinctive kind of certainty proper to the moral judgments of the virtuous person. Casuistry risked obscuring this fact by replacing an awareness of prudence’s integrated cognitive-appetitive character (for prudence is both intellectual and moral) with a kind of impersonal tally-sheet method for determining moral choices.

However, this confusion concerning the nature of probable certainty also had deep effects on the understanding of human knowledge and on the process by which we gradually attain to the essences and causes of things. By failing to take seriously the role of probable certainty in classical noetics, scholastic thinkers risked implicitly accepting the very terms of modern epistemology—committing, in their own way, the sin of Descartes, whom Maritain accused—rightly, I think, at least on the whole—of a kind of “angelism.”

In fact, what was Descartes’s position on probable certainty? It appears to have been rather bleak. In his manifesto of sorts, the Discourse on Method, it is precisely the probable certainty of philosophy that serves as his justification for dismissing the entire tradition of scholastic thought that preceded him. Where Ibn-Rushd tossed aside the religious thinkers for their dialectical reasoning, Descartes does the same for the philosophers:

Of philosophy I will say nothing, except that when I saw that it had been cultivated for many ages by the most distinguished men, and that yet there is not a single matter within its sphere which is not still in dispute, and nothing, therefore, which is above doubt, I did not presume to anticipate that my success would be greater in it than that of others; and further, when I considered the number of conflicting opinions touching a single matter that may be upheld by learned men, while there can be but one true, I reckoned as well-nigh false all that was only probable.

As to the other sciences, inasmuch as these borrow their principles from philosophy, I judged that no solid superstructures could be reared on foundations so infirm; and neither the honor nor the gain held out by them was sufficient to determine me to their cultivation: for I was not, thank Heaven, in a condition which compelled me to make merchandise of science for the bettering of my fortune; and though I might not profess to scorn glory as a cynic, I yet made very slight account of that honor which I hoped to acquire only through fictitious titles. And, in fine, of false sciences I thought I knew the worth sufficiently to escape being deceived by the professions of an alchemist, the predictions of an astrologer, the impostures of a magician, or by the artifices and boasting of any of those who profess to know things of which they are ignorant (Discourse on Method, pt. 1, trans. John Veitch, emphases added).

Admittedly, he shows himself conflicted, for he holds some esteem for those who at least have worked in the world (not at a mere scholar’s desk), and treats such men as having opinions worth listening to:

For these reasons, as soon as my age permitted me to pass from under the control of my instructors, I entirely abandoned the study of letters, and resolved no longer to seek any other science than the knowledge of myself, or of the great book of the world. I spent the remainder of my youth in traveling, in visiting courts and armies, in holding intercourse with men of different dispositions and ranks, in collecting varied experience, in proving myself in the different situations into which fortune threw me, and, above all, in making such reflection on the matter of my experience as to secure my improvement. For it occurred to me that I should find much more truth in the reasonings of each individual with reference to the affairs in which he is personally interested, and the issue of which must presently punish him if he has judged amiss, than in those conducted by a man of letters in his study, regarding speculative matters that are of no practical moment, and followed by no consequences to himself, farther, perhaps, than that they foster his vanity the better the more remote they are from common sense; requiring, as they must in this case, the exercise of greater ingenuity and art to render them probable. In addition, I had always a most earnest desire to know how to distinguish the true from the false, in order that I might be able clearly to discriminate the right path in life, and proceed in it with confidence (ibid.).

Yet, although he protests that he still holds esteem for the teaching of “the schools,” he is very clear that among all the subjects he lists, the one that receives the most dismissive treatment is philosophy, which “affords the means of discoursing with an appearance of truth on all matters, and commands the admiration of the more simple” (ibid.). If anything, the probable certainty of the philosopher appears to him as a kind of sophistry or, at best, a form of manipulative rhetoric suited for the simple. But, it would seem that the domain of opinion remains only for the practicalities of life, due to the uncertainty of practical and moral affairs (cf. “second rule” in ibid., pt. 3). For the attainment of the speculative, however, the task seems rather straightforward for him: one must root certainty in one’s own apprehension, with this becoming the determining criterion of truth: “I have always taken not to accord belief to new opinions of which I had not the most certain demonstrations, and not to give expression to aught that might tend to the hurt of any one” (ibid., pt. 3).

As noted already, Descartes appears somewhat conflicted on this matter. He is too well aware that human knowledge requires time and effort. Thus, something of the “positive skepticism” of dialectic remains present as an important moment in the project laid out in his manifesto. Nonetheless, the guiding spirit of his philosophical aspiration and outlook is most clearly revealed in the remark cited above: “I reckoned as well-nigh false all that was only probable….” He is not wrong to wish that truth be vitally assimilated by the individual knower, seen and contemplated personally. Yet where he errs—and even a small error at the start becomes immense over time—is in treating probability as “well-night false.” In so doing, he gives the impression that the human search for truth must, in the end, be “spun out” like a thread from a spider, generated from within the vital immanence of the knower and marked by a suspicion of whatever lies outside oneself and one’s own judgment. It is akin to the pride of the angel who would contemplate on the basis of the initial endowment of infused knowledge while rejecting the Source of that knowledge and His ongoing activity

But humans are not angels. And it is a great sin to mistake the angelic and the human. The task of being human is, in a real sense, to labor toward achieving humanity across a long arc of history. Our particular intellectuality is unique among intelligent beings precisely because it is historical in nature. Our knowing “lives,” so to speak, across generations. We enter the noetic labor of those who came before us, and we leave this noetic environment both more and less developed as we pass it to those who follow. Human knowing is a social and communal endeavor.

It makes sense, therefore, that this communality would be reflected in the very structure of the logic that governs our knowing. The point is not merely that each generation must undertake the labor of discovery (inventio). Taken by itself, such a claim remains ambiguous. A certain modern-liberal mindset happily affirms: yes, therefore, each of us must reclaim the truth anew, for oneself. But while this observation contains something true, it too often conceals an implicit denial—namely, that each person must, de iure, seek the truth as an individual accomplishment. Whatever role society plays would then become merely an occasion for one’s personal grasping of truth. Few would put the matter so starkly, but we should all remain attentive to the individualism that quietly accompanies such a view.

Rather, we enter the fray of knowledge from within a community of inquiry. We take our first positions on the basis of the proposition of those who speak to us with a kind of credibility (in the case of teachers) and with a kind of probability (in the case of “experts” with whom we can discuss the reasons for probability). In other words, we begin our reasoning by considering the positions held by all (for common sense contributes something to our basic encounter with reality), by many (for we must critically eliminate what is false), and by “the wise” (for there are those who, after much labor, truly see things clearly). To use the jargon of the tradition, we enter into the nexus of endoxa, the accepted opinions that serve as the starting point of knowledge as we begin our own labors in seeking the truth.

But our intellect is an intellect. In other words, we are not entirely ruled by the limitations of the bodily (which make our intellect discursively rational). Yes, because we are embodied, we must win our way to the truth and often fail to reach it. In this, our intellect experiences the limitations that befall all embodied beings—at times the form fails because of a deficiency of the matter. So too our reasoning fails, not always through sophistry, but even through very high probability: just as even the healthiest turtle will, someday, die.

But we are not constrained to death, and human knowledge can arrive at insight and the principles which are “self-evident.” Such self-evidence is subject to degrees, and it is often hard-won. But the tradition descending from Plato and Aristotle is correct in holding that we can truly see reality intellectually, that definitive acquisitions are possible in human knowing. On the basis of such acquisitions, it becomes possible to reason toward necessary conclusions, such that human knowing attains true demonstration. These are difficult achievements. And although the scholastic tradition rightly recognizes that insight into first principles is what makes us most angelic (most intellectual), I would argue that even in the discursive, rational work of our knowing, we draw near to the angelic whenever we see conclusions in principles—that is, whenever we have scientific demonstration. Scientific demonstration is rare, and it is the closest discursive analogue to the way an angel sees a plurality of truths within a single truth.

But the mind must labor in the midst of embodied knowledge. This is simply a fact of our particular intellectual structure. The spiritual soul is the form of the body, and it requires the senses and the phantasms in order to win its way gradually toward the truth. And this task is universal. Our intellectual work tends toward definitions and demonstrations in all matters. We seek to know the what and the why. We have a natural aptitude to discuss all things, seeking to use every logical tool in our toolkit, not merely the proper per se (i.e., scientific) principles of this or that particular subject under consideration.

The logic of this labor is dialectical logic. It is not a “merely probable” substitute for the only truly useful kind of knowledge, demonstrative knowledge. Instead, it is the natural labor of the mind as it inherits a tradition for itself and continues to explore the vast terrain of all being, for which the intellect is made to unite itself.

It is here that we must make important remarks about probable certainty. (I recommend that the reader also consult Gardeil’s text on this, which I have translated for online use, as well as a relevant section of his articles dedicated to theological “loci”.) At first glance, the expression may seem contradictory. “Probable” appears to negate “certainty.” Yet it does not. Probability designates the particular kind of certainty belonging to truths that are not mere doubts but possess a real verisimilitude ad verum, a likeness to truth. In other words, probable truths are truths “on the way,” supported by a series of reasons that militate on behalf of this truth against its competitors. These reasons may arise from the intrinsic labor of argumentation or from the extrinsic authority of those whom we have good reason to believe have attained the truth they propose.

Such probable certainty gives rise to an opinion. By this I do not mean simply one position among many, but rather a position supported by arguments sufficiently strong to justify holding it, among all known alternatives, as the position to be held at this time. It is not characterized merely by diminished doubt or suspicion but by “probability”—that is, by its being truer than the others that one has considered in some way. (And thus, one can, without paradox, say that the mark of the classic notion of probability is, in fact, in modern jargon, probabiliority.) When such a state of mind is achieved, we are justified in holding this position even if we do not yet apprehend its intrinsic reasons (whether by direct insight in the case of per se nota truths, or by demonstrative reasoning). Such opinions function as a kind of “foresight” of definitive knowledge, such that we can even attain a genuinely stable opinion (opinio vehemens), which stands as a transitional state between opinion and certainty (whether the certainty of insight or of demonstration). Here the knower does not yet see the intrinsic reason for the connection between subject and predicate, but nevertheless possesses a cluster of strong reasons for holding the position. We stand somewhat like a sailor who knows the shore is there, though he cannot yet see it. Thus arises a certain “fear of error,” born from the fact that the intellect has not yet settled itself upon intrinsic evidence or upon intrinsic, demonstrative reasons for the truth in question. And yet, all the same, we remain certain—not demonstratively certain, but vehemently–probably certain:

And thus, when the hard work of discovery, of inventio, comes to its close, when the probable, that “dawning radiance of tomorrow’s science,” rises at the end of a laborious night, the man who lives his life precisely as a man—under the scientist absorbed in the progress of his thought—naturally and inevitably feels a sense of dread—“What if this possibility of error, as yet unreduced to certainty, were suddenly to spread out like a dark cloud in a stormy sky! What if today’s contingency became tomorrow’s error!” He does not doubt… He remains attached to the ray of light filtering through the clouds, like the captain upon his bridge in the dark of night, with eyes fixed upon the lighthouse on the shore, alternately shining and then disappearing back into the darkness. But, because he cannot yet see the luminous source of this ray, he experiences a feeling of dread. This fear is not essential to opinion, but in the man who thus opines, it naturally springs forth, per se, ex natura rei (Gardeil, “Probable Certainty”)

The work of dialectic is what helps us to reach this kind of certainty—gradually, step-by-step. Beginning from the endoxa of our personal and contemporary intellectual environment, it moves outward toward the definitive acquisition of truth. Dialectic and probability are not yet fully settled in the truth, but they make sense only in view of its definitive acquisition. The definitive dicendum quod is the desired terminus of any honest labor of inventio and disputatio. Dialectic is positive skepticism—a positive σκέψις (skepsis), an investigation into the truth. It is only when one denies the experience of definitive acquisitions—and such acquisitions can be shown to be a completely certain experiential datum of human intellectual life—that dialectic devolves into negative skepticism: an endless desire to destroy all positions, not merely to test them for their truth, but to show continually that nothing at all is certain, that reality itself floats on the surface of an ever-changing, never-stable flux. Negative skepticism is, ultimately, a denial of the logos-structure of reality.

The work of dialectic is not, however, a lonely affair. I sometimes say, somewhat lightheartedly, that in the Topics Aristotle is trying to give an account of “what the heck” Socrates was doing whenever he was debating people in the streets of Athens, and what the members of the Platonic Academy were doing in their constant discussions. More seriously, the Topics seeks to articulate the general structure of what the human person does when intellectually seeking the truth by way of dialogue. Such dialogue sometimes unfolds only within our own mind: we posit a position, consider the reasons that militate against it, and then examine whether those reasons strengthen the position or give solidity to the opposing one, which now seems more plausible. But it is rare to find a mind capable of sustaining this entirely on its own, and thus most of us must undertake this labor with another person. Hence the need for a ready method by which a “common work” might be achieved through question and response, enabling us to articulate a provisional truth that we will continue to test and refine.

This is why dialectic (or its native environment, dialogue) can seem so very destructive. It is indeed a kind of skeptical undertaking, one that tests whether the reigning opinion can in fact be destroyed—not because it is “well-nigh false,” but because it has not yet emerged into a state of evidence or demonstration. Gradually, as repeated back-and-forth argumentation fails to overthrow the position in question, we arrive at a stable state of quite solid probability. And although dialectic can ascend no further, it is precisely the preparatory work for a kind of intellectual substantial change, disposing the knower for that moment when he or she may (perhaps) definitively grasp the truth.

I say “perhaps” because much of our intellectual life is lived in the midst of probable certainty. It is very difficult to reach insight or demonstration, even for the ablest of minds. Evidential knowledge of principles and demonstrations is an achievement to be cherished, and typically the fruit of considerable intellectual preparation and labor. Such achievements, once they enter the intellectual life of a culture, deserve to be protected as noble accomplishments of the human spirit. But for all of us, even truths that are indeed “self-evident” (per se nota) may, owing to the contingencies of our particular intellectual formation, remain known only within the bounds of opinion. And this is all the truer when dealing with matters that are themselves objectively contingent—a domain in which probable certainty most properly reigns. (On the various kinds of contingency involved in probable certainty, see “Influence of the contingency of the probable on opinion,” as well as the entries on “contingent” and “contingency” in the aforementioned article by Gardeil.)

The Topics of Aristotle is dedicated to unfolding this question-and-answer task. It contains several major components. One essential skill the dialectician must acquire is the ability to maintain a discussion at the level of a common search for a truth that is not yet known, without allowing it to devolve into sophistry, mere sport for victory, or a didactic exercise in which one party already possesses the truth. Another indispensable tool is the set of general “instruments” used for generating possible propositions—potential theses and their corresponding oppositions—to be tested within the dialectical exercise. And, most famously and in greatest detail, the Topics presents the treatment of problems and their loci, the particular “natural places” from which maxims arise that function within dialectical syllogisms.

For the purposes of the Topics—which is meant to be a general work of logic, applicable to the most common problems encountered in day-to-day intellectual life—Aristotle distinguishes moral questions (treated more briefly in the Topics, but receiving important development in the Rhetoric), physical questions (which, interestingly, draw upon certain common principles from the Categories, such as the general nature of qualities, quantities, and so forth), and “logical questions” (the principal concern of the Topics itself). The central books of the treatise are devoted to the general principles that allow us to investigate whether an attribution has the modality of genus (and species), definition, property, or an accident. It is precisely at the level of these specific inquiries that our seminar concluded its work for the semester. Below, I will offer a few resources to guide further engagement with these sections of the Topics. Even so, it was already a considerable labor merely to reach this point of preparation—and it would have been impossible without the helpful guidance of Pelletier and Gardeil.

To say that dialectical logic must be recovered is no nostalgic attempt to reinstate “classical purity.” Rather, it represents an honest appraisal of the human scale of knowing. Insight and demonstration remain the apex of discursive reason—but they are a terminus, not the long and arduous via by which we humans seek out the truth. We advance toward science through dialogue, through the disciplined testing of received positions (endoxa), gradually acquiring probable certainty. It is through the communal labor of seeking what is ever better that we move toward the truth—both as individuals and as societies. Dialectic, when rightly practiced, guards against the arrogance or angelism that treats the intellect as an x-ray machine, and against the despair of negative skepticism or pragmatism, which abandons hope for any definitive intellectual acquisitions. In short, the practice of dialectical logic preserves the embodied, historical humanity of our knowing. It reminds us that the movement from ignorance to insight and demonstration is not the lonely ascent of a soldier-philosopher sitting alone by his stove, but the shared work of those who reason together, trusting that truth, however difficult, is indeed attainable. To retrieve this heritage of dialectic is to bolster our confidence in the rational and social nature of the human person, who communally seeks truth definitively acquired.

Several resources and bibliography

Summary of various kinds of assent

Evident assent: firm and evident assent

• Directly, “self-evident” or per se nota truth (intellectus, assensus sine cogitatione)

• Discursive, demonstrative certainty (scientia, cognitio et assensus)

Doubt (nihil de assensu, sed tantum de cogitatione): devoid of firm assent on both sides
Suspicion: very slight motive for inclining to one side
Conjecture: based upon quick observation (solertia as a virtue helps)
Hypothesis: a position posited for possible investigation (“let’s consider X…”)

Probable certainty / opinion (cognitio sine assensu perfecto, but “on the march”): to incline toward one side for good reasons; reveals the intrinsic truth of the object, but only in limited fashion; opinion is a diminished and imperfect act (deprived of absolute, evident knowledge)

• Occasionally absolutely probable (according to some theorists, but not all, fear is not experienced)

• Most often merely probability (=probabiliority in the modern sense). Fear fought by the executive agency of the will, removing prohibiting factors and positively determining only the exercise of the will

• Sometimes, probability is purely dialectical; sometimes it is rhetorical (where affect plays a more essential role, closer to specifying)

Faith / Belief (assensus cum cogitatione): will operative through freedom of specification (assent occurs under motion of will); imperfect act and does not reveal the intrinsic truth of the object (deprived of evidence / vision)

• Involves arguments for (speculatively-practical) rational credibility for believing the person whom one believes. (Note: belief differs from opinion through the distinction between credibility in authority, in contrast to opinion which involves dialectical argumentation for the very position itself.)

• But also involves “reasons of the heart” (affective inclination on the goodness of the assent, either objectively or, at least, merely because truth is the good of the intellect)

Prudence: the will is incredibly important throughout (deep freedom of specification) for deliberation, judgment, and command; the practical intellect determines the will (in the order of extrinsic formal causality) and the will determines the practical intellect (in the order of efficient causality, by freedom of specification and exercise)

Assent to merely apparent truth, not known as such (sophistry)

Ignorance, no knowledge (nihil de assensu aut de cognitione)

Bibliography and Other Resources

• Slide-notes from lectures / discussions for Lyceum Institute

• Charts for various dialectical situations (referenced in lecture), drawn from Pelletier

• Rough outline of loci from Themistius and Peter of Spain Loci for Lecture (referenced in lecture, but it is important to note that these are not arranged the same as Aristotle)

• Albert the Great’s Topica Commentary (Rough Draft Side-by-Side Translation Chat GPT – thanks to Mitchell Kengor [now, Br. Hyacinth Kengor, OP] and Dr. Matthew DuBroy for help transcribing this)

Albert the Great. In Aristotelis octo libris Topicorum commentaria. Parisiis: Vivès, 1890. (See above for sketch translation.)

Alexander of Aphrodisias. On Aristotle’s Topics. Books 1–3, trans. Johannes M. van Ophuijsen (vol. 1) and Laura M. Castelli (vol. 2 and 3). London: Bloomsbury, 2014–2021.

Aristotle. Topics, Topics Books I and VIII. Translated with commentary by Robin Smith. Oxford: Clarendon Press, 1997.

———. Topics Book VI. Translated with commentary by Annamaria Schiaparelli. Oxford: Clarendon Press, 2024.

Averroes. Averroes’s Three Short Commentaries on Aristotle's “Topics,” “Rhetoric,” and “Poetics.” Edited and translated by Charles E. Butterworth. Albany, NY: SUNY Pres, 1977.

———. Middle Commentary on Aristotle’s Topics. Trans. Charles E. Butterworth and Ahmad Abd al-Magid Haridi. Cairo: The American Research Center in Egypt, 1979.

Boethius. De topicis differentiis. Translated and edited by Eleonore Stump. New York: Cornell University Press, 2004.

Byrne, Edmund. Probability and Opinion: A Study in the Medieval Presuppositions of Post-Medieval Theories of Probability. The Hague: Martinus Nijhoff, 1968.

Cicero. Topica. Edited, Translated, and Commentary by Tobias Reinhardt. Oxford: OUP, 2002.

De Pater, W.A. Les Topiques d'Aristote et la dialectique platonicienne, méthodologie de la définition. Fribourg: St-Paul, 1965.

Gardeil, Ambroise. “La certitude probable,” Revue des sciences philosophiques et théologiques 5 (1911), 441-485. Translation available at https://www.athomist.com/s/Gardeil-Probable-Certainty-FULL.pdf

———. La notion du Lieu théologique (Paris: Gabalda, 1908). Translation by Matthew K. Minerd available at https://www.athomist.com/articles/ambroise-gardeil-the-notion-of-a-theological-locus-complete-text.

———. “Overview of Aristotle’s Topics” in La notion du Lieu théologique. Paris: Gabalda, 1908. Translation available at https://www.athomist.com/s/Final-Gardeil-Lieux-RSPT.pdf.

Newman, John Henry. An Essay in Aid of a Grammar of Assent. Notre Dame, IN: University of Notre Dame Press, 1992.

Pelletier, Yvan. La dialectique aristotélicienne: Les principes clés des Topiques. Laval: Société d’Études Aristotéliciennes /Bellarmin, 1991. (Detailed bibliography in this text. Very important text for anyone working on this topic in much greater detail than I ever will.)

———. “L’articulation de la dialectique aristotelicienne.” Angelicum 66 (1989): 603-620.

Régis, Louis-Marie. L’opinion selon Aristote. Paris: Vrin, 1935.

Richard, Timothée. “Les conditions de la certitude et la critique.” Revue thomiste (1904): 682–705.

———. “Autour de la probabilité unique.” Revue thomiste (1905): 165–195.

———. “De la nature et du rôle de l'induction d'après les anciens.” Revue thomiste (1908) 301–310, 411–421.

———. “Des causes de l’assentiment dans la croyance et l'opinion.” Revue Thomiste (1910): 590—617. (Translation will be made available on To Be a Thomist.)

———. “Du raisonnement en matière contingente dans la science moderne.” Revue thomiste (1909): 313–336.

———. “Pensée et affection.” Revue Thomiste (1905): 418–437. (Translation will be made available on To Be a Thomist.)

———. “A propos d'un article récent sur le probabilisme - Etudes critiques.” Revue thomiste (1924): 404–415.

———. “Notion philosophique de l’opinion.” Revue Thomiste (1920): 319–348. (Translation will be made available on To Be a Thomist.)

———. “La probabilité et la raison pratique.” Revue thomiste (1926): 503–516; (1927): 61–71.

———. “Probabilité unique ou douteuse - Précisions et réponses - Notes et discussions.” Revue thomiste (1925): 452–473.

———. Le probabilisme moral et philosophie. Paris: Nouvelle Libraire Nationale, 1922.

———. Philosophie du raisonnement dans la science: d'après saint Thomas. Paris: Maison de la Bonne Presse, 1918.

———. Études de théologie morale: (1) Le plus parfait. Doctrine et pratique. (2) De la probabilité à la certitude pratique. Paris: Desclée de Brouwer, 1933.

Rubinelli, Sara. Ars Topica: The Classical Technique of Constructing Arguments from Aristotle to Cicero. New York / Berline: Springer, 2009.