Logic (2016) #
A comprehensive treatment of classical Aristotelian logic. These lectures cover the three acts of reason, the ten categories, syllogistic reasoning, and dialectical tools as presented by Aristotle and St. Thomas Aquinas, providing the foundational art for all philosophical and theological inquiry.
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Lectures #
1. Logos, the Three Acts of Reason, and the Division of Logic #
This lecture explores the equivocal nature of logos (word, thought, and reason) and its theological significance in John’s Gospel, then systematically examines Thomas Aquinas’s division of logic into three parts corresponding to the three acts of reason: simple understanding, composition/division, and reasoning. Berquist compares Thomas’s three-part division with Albert the Great’s two-part division (defining and reasoning), and establishes the foundational distinction between names and speech as the basic building blocks of logical discourse.
2. Logic, Predication, and the Three Acts of Reason #
This lecture explores the foundational structure of logic as the discipline directing the acts of reason. Berquist examines how logic proceeds by way of predication, distinguishes Thomas Aquinas’s threefold division of logic (based on three acts of reason) from Albert the Great’s twofold division, and explains the natural progression from sensible words to intelligible concepts. The lecture establishes how definition, statement, and argument correspond to the three acts and emphasizes logic’s role as the ‘art of arts’ that directs reason itself.
3. Equivocal Names and the Five Predicables #
This lecture explores how words become equivocal by reason—through dropping part of their meaning or proportional extension—and introduces Porphyry’s five predicables (genus, species, difference, property, and accident) as fundamental to understanding definition, division, and demonstration. Berquist demonstrates the practical utility of these concepts across mathematics, ethics, politics, and natural philosophy, emphasizing the epistemological and ontological ordering of predicables and how property differs from accident through connection to nature.
4. Porphyry’s Isagoge and Aristotle’s Categories: Genus, Species, and Highest Genera #
This lecture examines Porphyry’s treatment of genus and species in the Isagoge, explaining why species is defined by its relation to the genus above it rather than by what is below it. Berquist explores the logical principle that not every genus can have a genus above it (avoiding infinite regress), leading to the question of highest genera. The lecture then turns to Aristotle’s Categories, analyzing the three types of names—equivocal (homonyma), univocal (synonyma), and denominative (paronyma)—and establishing that ‘being’ cannot be a single highest genus because it is not said univocally of all things.
5. Categories Chapter 2: Being Said Of and In a Subject #
Berquist examines Aristotle’s foundational distinctions in Categories Chapter 2, analyzing the fourfold division of beings based on whether things are said of a subject and whether they exist in a subject. The lecture demonstrates how these distinctions prepare the ground for understanding the ten categories, with particular emphasis on individual substance as the fundamental subject of predication and how all other things are predicated of individual substances in different ways.
6. The Ten Categories and their Enumeration #
This lecture completes Aristotle’s Anti-Predicaments by enumerating and exemplifying the ten highest genera (categories). Berquist examines Aristotle’s deliberate use of concrete terminology (poson, poion, prosti) rather than abstract terms, explains why substance is privileged as the first category, and illustrates how each category is distinguished by the way predicates are said of individual substances. The lecture emphasizes the importance of precise translation and concrete language for understanding both Aristotelian logic and Trinitarian theology.
7. The Ten Categories and Modes of Predication #
This lecture explores Aristotle’s doctrine of the ten categories (predicaments) as the highest genera of being, focusing on how they are distinguished by the modes in which things are predicated of individual substances. Berquist explains why being is not univocally said of all things but rather equivocally by reason, and demonstrates Thomas Aquinas’s three-fold division of predication: by essence, by inherence in the subject, and by extrinsic denomination. The lecture emphasizes the connection between logic (modes of predication) and ontology (modes of being), grounding metaphysical understanding in foundational philosophical distinctions.
8. Aristotle’s Four Causes and the Ten Predicaments #
This lecture explores Aristotle’s distinction of four causes (material, formal, efficient, and final) as the organizing principle for understanding Thomas Aquinas’s exposition of the ten categories or predicaments. Berquist uses concrete examples to demonstrate how substance, accidents, and extrinsic denominations are systematically derived from the ways things can be predicated of individual substances, with particular focus on how the efficient cause generates the categories of action and passion, and how extrinsic measures (time and place) yield their own predicamental categories.
9. Being, Predication, and the Ten Categories #
This lecture explores Aristotle’s division of being through the framework of predication and the ten categories. Berquist examines how being cannot be treated as a genus, how words like ‘being’ are equivocal by reason with ordered meanings, and how the ten highest genera (categories) are distinguished by the diverse ways something can be said of individual substances. The lecture carefully distinguishes three fundamental ways predicates relate to subjects: signifying what the subject is (substance), signifying something in the subject (quantity and quality), and signifying something outside the subject (relation, action, passion, habitus, when, where, and position).
10. Equivocal Terms by Reason and Theological Applications #
This lecture explores how words become equivocal by reason—a fundamental concept for understanding how a single term can have multiple ordered meanings across different contexts. Berquist demonstrates three primary ways equivocation by reason occurs: when one thing keeps a common name while another receives a new name, when part of a term’s meaning is dropped in generalization, and when a name is carried over by reason of proportion or likeness of ratios. The lecture illustrates these principles through philosophical examples (substance, habit, sensation, motion) and theological applications (the Trinity, divine attributes, the relationship between philosophy and revealed theology).
11. Substance, Equivocation, and the Division of Categories #
Berquist explores Aristotle’s treatment of substance in the Categories, examining why Aristotle divides substance into first and second substance rather than into species as he does with quantity and quality. The lecture centers on understanding equivocal words by reason—words with multiple meanings ordered among themselves—as essential for grasping the distinction between individual substance and universal substance, and for understanding how substance can be predicated of both while remaining fundamentally ordered toward the first substance.
12. Equivocation by Reason and the Properties of Substance #
This lecture explores equivocation by reason as distinct from equivocation by chance, examining three primary ways terms become equivocal by reason: through one thing keeping a name while another receives a new name, through dropping part of a term’s meaning, and through proportional relationships (analogy). Berquist also introduces the properties of substance from Aristotle’s Categories, distinguishing first and second substance and examining how the categories relate to understanding being itself.
13. Substance, Categories, and the Trinity #
This lecture continues discussion of Aristotle’s categories with focus on the properties of substance, particularly how substance differs from accidents in terms of contraries and individuation. Berquist explores the distinction between first and second substance, examines how definition applies to substances versus accidents, and concludes with extended theological application to the hypostasis of Christ and the Trinity, including numerical symbolism in Thomas Aquinas’s treatment.
14. Order, Beauty, and the Distinction of Being #
Berquist explores the fundamental importance of order in understanding reality, connecting Shakespeare’s definition of reason as ’looking before and after’ with Aristotle’s account of order as the first form of beauty. The lecture moves from aesthetic and rational principles to examine the most basic distinctions in being, asking whether the distinction between being and non-being, or between being in act and potency, is more fundamental than the distinction of the ten categories.
15. Continuous and Discrete Quantity: Definitions and Measures #
This lecture examines Aristotle’s division of quantity into discrete (number) and continuous (magnitude) categories, focusing on why these categories receive different definitions in logic versus natural philosophy. Berquist explores how the logician defines continuous quantity affirmatively (parts meeting at a common boundary) while the natural philosopher defines it through divisibility, and explains why numerical measure is more fundamental than physical measure due to the simplicity of the indivisible one.
16. Quantity, Measure, and the Nature of Number #
This lecture explores the nature of quantity as divisible into parts, examining the fundamental distinction between discrete and continuous quantity. Berquist discusses how different types of quantity are measured, the role of the one as measure, and the relationship between the one convertible with being and the one that begins number. The lecture traces through Aristotelian categories and Thomistic metaphysics to clarify how reason apprehends quantity through its parts.
17. Perfect Numbers, Proportions, and the Properties of Quantity #
This lecture explores the mathematical foundations underlying philosophical categories, particularly the properties of quantity and the role of proportion in understanding discrete and continuous quantities. Berquist examines how perfect numbers and proportional relationships illuminate the nature of quantity’s individuation, its distinction from accidents like quality, and its special proximity to substance. The discussion connects mathematical abstractions to theological problems, especially the Eucharist and the individuation of material substances.
18. Conceptions, Abstractions, and the Nature of Number #
This lecture examines how the understanding conceives of things in three distinct ways: as likenesses of external things, as intentions that follow from the way of understanding, and as false conceptions with no foundation in reality. Berquist explores the relationship between abstract conceptions (particularly mathematical abstractions) and things, using the example of number to illustrate profound difficulties about unity, composition, and how multiplicity relates to being. The discussion culminates in theological applications regarding the Trinity and God’s omnipotence, showing how mathematical abstraction differs from physical reality.
19. Relation, Order, and the Nature of Towards-Something #
This lecture examines Aristotle’s category of ’towards-something’ (ad aliquid/πρός τι), exploring why Aristotle deviates from his enumerated order of categories to discuss relation before quality. Berquist analyzes the distinction between relatives secundum dici and relatives secundum esse, examines properties of relations including reversibility and co-knowledge, and discusses the metaphysical implications of relations for understanding substance, unity, and theological concepts like the Trinity.
20. Logic, Predication, and the Categories #
This lecture explores the fundamental distinction between logic and natural philosophy, examining how logic proceeds by way of predication while natural philosophy proceeds by way of motion. Berquist analyzes the predicables (genus, difference, species, property, accident) and the ten categories, emphasizing the Aristotelian framework for understanding how things are said of other things. The lecture traces these concepts through Cajetan’s commentary and Thomas Aquinas’s application to both metaphysics and theology.
21. Relations: Secundum Esse, Secundum Dici, and Real Relations #
This lecture explores Aristotle’s category of relation (ad aliquid), focusing on the medieval distinctions between relatives secundum esse versus secundum dici, and between real relations and relations of reason. Berquist clarifies why certain things (like knowledge and power) are fundamentally qualities rather than relations, and applies these logical distinctions to theological problems in Trinitarian theology, particularly how the Father generates the Son while maintaining divine simplicity.
22. The Category of Relation and Its Foundations #
This lecture explores the Aristotelian category of relation (ad aliquid), examining how things whose whole nature is to be toward another differ fundamentally from substance and other accidents. Berquist clarifies the distinction between relative secundum esse (things that are purely relational) and relative secundum dici (things fundamentally belonging to another category with relations following upon them), addresses why relations are real in creatures but not accidents in God, and explains how Thomas Aquinas applies these principles to understand divine relations in the Trinity.
23. God’s Immutability and Real Relations in the Incarnation #
This lecture explores the unchanging nature of God’s substance in relation to the Incarnation, examining how the union of divine and human natures involves real relations in the human nature but only relations of reason in the divine nature. Berquist discusses Thomas Aquinas’s treatment of relations as either real or rational, using examples of quantity and action/passion as foundations for real relations, and applies this framework to understanding how God can create and sustain creatures without undergoing change.
24. Relations of Reason and Five Kinds of Defective Relations #
Berquist examines Thomas Aquinas’s distinction between real relations and relations of reason, focusing particularly on five kinds of relations of reason that fall short of being true relations. The lecture explores how the understanding attributes order and relation to things that may not possess these relations in reality, and distinguishes between relatives secundum esse (according to being) and secundum dici (according to being said). Key examples include temporal relations (before and after), relations involving non-existent things, and the asymmetrical relation between the knowable and knowledge.
25. Quality and Its Four Species in Aristotle #
This lecture examines Aristotle’s treatment of quality as a category, focusing on its four species and how they relate to one another. Berquist explores the properties that distinguish quality (having contraries, admitting of more and less, conferring likeness or unlikeness), traces the linguistic connection between quality and the word “how,” and argues for understanding the four species through the principle of division by two or three. The lecture connects quality to virtue and vice, examines why certain species are more fundamental than others, and considers how quality differs from quantity and relation.
26. Quality, Modus, and the Four Species of Determination #
This lecture explores how Thomas Aquinas uses the term modus (mode, measure, boundary, limit) to distinguish the four species of quality and their different modes of determining a subject. Berquist examines why Thomas applies modus to quality despite it being associated with quantity, arguing that quality determines the subject according to nature, action/passion, and quantity itself. The lecture addresses the linguistic puzzle of how ‘modus’ and ‘determinatio’ function as synonyms and how measurable things must be limited, connecting this to Shakespeare’s use of ‘immeasurable’ and ‘infinite’ and the Fourth Lateran Council’s terminology for God.
27. The Four Senses of End and the Four Species of Quality #
This lecture explores Aristotle’s analysis of the term ’end’ (telos) in Metaphysics V, distinguishing four senses: the terminus of magnitude, the limit of motion, both extremes of motion, and the essence/definition of a thing. Berquist then connects this framework to the four species of quality in the Categories, examining why quality is equivocal ‘by reason’ rather than univocal, and develops thomistic applications to grace and theological virtues.
28. Quality, Character, and the Continuous Foundation of Analogical Language #
This lecture examines the nature of sacramental character and its classification within the species of quality, ultimately rejecting placement in the first, third, and fourth species before settling on the second species as a spiritual power. Berquist emphasizes how Thomas Aquinas’s insight that equivocal theological terms derive primarily from the continuous (magnitude, motion, time) provides the philosophical foundation for understanding how we speak analogically of God and supernatural realities. The discussion connects Shakespeare’s definition of reason with Aristotle’s treatment of act and potency, demonstrating how the continuous underlies our understanding of foundational concepts like beginning, end, form, and discourse.
29. The Final Six Categories and Post-Predicamental Concepts #
Berquist concludes his treatment of Aristotle’s ten categories by examining the final six (where, when, position, having, acting upon, undergoing) and introduces the post-predicamental concepts (opposites, order, motion, having). He emphasizes how understanding place and time as extrinsic measures requires transcending spatial imagination, and explores how these categories illuminate both natural philosophy and theological concepts like God’s eternal knowledge.
30. Post-Predicaments: Opposites and Distinction #
This lecture explores Aristotle’s doctrine of post-predicaments—concepts like opposites, before and after, and having that transcend single categorical placement. Berquist examines the four kinds of opposites (relatives, contraries, privation, and contradictories), their ordering, and their fundamental role in how reason operates through distinction. The lecture emphasizes how opposites are essential not only for subdividing categories but for understanding divine persons in theology and the universal structure of human thought.
31. The Post-Predicaments: Before, After, Together, and Having #
This lecture examines four of Aristotle’s post-predicaments—words that apply across multiple categories. Berquist focuses on the distinctions between different senses of ‘before’ and ‘after,’ the concept of ’together’ (hama/simul) defined by negation of before/after, and the seven senses of ‘having.’ Throughout, he emphasizes how these terms are named from the continuous (magnitude, motion, time) and traces their applications to understand order, distinction, and possession both in created things and in God.
32. The Four Kinds of Opposites and Divine Distinction #
This lecture explores Aristotle’s classification of opposites—relatives, contraries, privation, and contradictories—and their philosophical significance for understanding distinction, particularly in theology. Berquist examines how formal distinction in God must occur through relations rather than other forms of opposition, and discusses how opposites are foundational to how the mind distinguishes things. The lecture also addresses evil as privation and the nature of ignorance versus error.
33. The Trinity and the Senses of Before #
Berquist examines whether the Father is before the Son in the Trinity, using Thomas Aquinas’s analysis of the four senses of ‘before’ drawn from Aristotle’s post-predicaments. Through logical analysis of duration, nature, understanding, and dignity, the lecture demonstrates how formal distinction by relation (rather than temporal priority) preserves the equality and eternity of the divine persons. The discussion shows how abstract logical categories apply directly to Trinitarian theology and reveals the fundamental importance of the post-predicaments for Christian doctrine.
34. Motion, Change, and the Three Acts of the Intellect #
This lecture examines Aristotle’s classification of motion across the categories (generation/corruption, growth, alteration, and locomotion) and their hierarchical ordering in natural philosophy. Berquist then transitions to logic, introducing the three acts of the intellect—understanding what a thing is, understanding truth/falsehood through composition and division, and reasoning through argumentation—with emphasis on how these acts involve different relationships between concepts and how distinct knowledge emerges from confused knowledge.
35. The Eight Senses of ‘In’ and Thinking Out #
This lecture explores Aristotle and Thomas Aquinas’s analysis of the eight primary senses of the word ‘in’ (as in ’to be in’), from spatial location to final causality. Berquist demonstrates how each sense of ‘in’ corresponds to different ways that reason ’thinks out’ or articulates knowledge, showing that equivocal words are essential to philosophy. The lecture examines concrete examples of these senses and their application to understanding definitions, logical reasoning, and even theological concepts like the Trinity.
36. Definition, Statement, and the Structure of Reasoning #
This lecture distinguishes between definition and statement as two fundamental types of speech in logic. Berquist clarifies that while both are vocal sounds that signify, definitions are speech signifying what a thing is, whereas statements are speech signifying the true or false. The lecture explores the grammatical and logical structure of statements, including simple statements (composed of noun and verb) and compound statements (disjunctive, conditional, and conjunctive), with particular attention to how conditional if-then statements function logically.
37. If-Then Syllogisms and the Three Figures of Categorical Syllogisms #
This lecture covers the structure and validity of if-then (conditional) syllogisms, examining which of the four possible forms yield necessary conclusions and which do not. Berquist then transitions to categorical syllogisms, introducing the three figures determined by the position of the middle term, and establishes the foundational principles of the dictum de omni and dictum de nullo. The lecture explains why the first figure is most powerful and introduces the concept of conversion of propositions as essential for reducing the second and third figures to the first.
38. Conversion of Propositions and the First Figure of the Syllogism #
This lecture examines the conversion of categorical propositions (universal affirmative, universal negative, particular affirmative, and particular negative) and their differing degrees of logical power and necessity. Berquist analyzes the four universal cases of the first figure of the syllogism, demonstrating valid and invalid forms through examples, and establishes why the first figure is logically superior. The lecture also explores the nature of reason’s self-knowledge and the relationship between logic and wisdom as forms of inward philosophy.
39. The Three Figures of the Syllogism and Their Validity #
This lecture systematically explores the three figures of the syllogism, examining which conclusions necessarily follow from premises in each figure. Berquist demonstrates how to prove invalidity through counterexamples and explains why the figures possess different logical power, with the first figure being most powerful and the third least powerful. The lecture emphasizes the distinction between matter (the truth of premises) and form (the necessity of conclusion), showing how students can be deceived by true conclusions that don’t follow from the given premises.
40. Compound Statements and the Forms of Argumentation #
This lecture examines the nature and types of compound statements—disjunctive (either-or), conjunctive (and), and conditional (if-then)—and their role in reasoning and argumentation. Berquist explores how truth operates differently in compound versus simple statements, demonstrates valid forms of conditional reasoning, and discusses how compound statements function in logical discourse, with particular attention to how they structure theological claims and philosophical arguments.
41. Induction, Example, and Enthymeme in Reasoning #
This lecture examines three forms of non-syllogistic argument: induction, example, and enthymeme. Berquist explores how these arguments differ from the syllogism in their use of particulars versus universals, demonstrates two distinct senses of induction (from singulars to universal, and from less universal to more universal), and illustrates how Thomas Aquinas employs inductive reasoning in theological demonstration. The lecture also discusses the second figure of the syllogism and the conversion of propositions.
42. Syllogistic Figures and the Validity of Arguments #
This lecture examines the three figures of the syllogism, analyzing why the first figure is more powerful than the second and third figures. Berquist explores how conversion affects the validity of syllogistic forms, explains why certain figures can only yield particular conclusions, and demonstrates how to test syllogistic validity through counterexamples. The lecture also distinguishes between necessary conclusions and those requiring conversion to be evident.
43. Humility in Philosophy and the Three Figures of Syllogism #
This lecture examines the role of humility in philosophical inquiry, emphasizing how docility to wiser thinkers prevents pride-based errors in judgment. Berquist then transitions to formal logic, explaining the three figures of the syllogism, their proper ordering, the four universal cases within each figure, and why certain figures can only produce particular conclusions. The lecture demonstrates how formal validity differs from material truth and why examples cannot prove a syllogistic form is valid.
44. God’s Attributes: Simplicity, Perfection, Unity, and Infinity #
This lecture examines Thomas Aquinas’s treatment of God’s essential attributes as presented in the Summa Contra Gentiles and Compendium Theologiae. Berquist explores how simplicity and perfection correlate with unity and infinity, discussing the theological significance of God’s absolute simplicity, boundless perfection, and uniqueness. The lecture also addresses why God’s perfection (rather than simplicity) is more readily grasped as endless, and how these attributes relate to God’s immutability as a logical consequence of divine perfection.
45. Syllogistic Form, Matter, and Demonstration versus Dialectic #
This lecture explores the distinction between the form and matter of a syllogism, contrasting demonstrations (which employ necessary truths) with dialectical syllogisms (which employ probable opinions). Berquist uses concrete examples and the analogy of arithmetic operations to clarify how a syllogism can have correct logical form while possessing either true or false premises, and discusses how Aristotle and Thomas Aquinas treat these distinctions in their logical and theological works.
46. Definition, Demonstration, and the Art of Dividing #
This lecture explores the relationship between definition and demonstration, showing how a perfect definition mirrors the structure of a syllogistic proof. Berquist examines Albert the Great’s division of logic into the art of defining and the art of reasoning, then develops the principle of binary and ternary divisions for understanding complex distinctions, illustrating this with Porphyry’s five predicables, Aristotle’s ten categories, eight meanings of ‘in,’ and four senses of ‘cause.’
47. Demonstration, Definition, and the Four Tools of Dialectic #
This lecture explores the relationship between demonstration and definition as two forms expressing the same logical content in different structures, then transitions to Aristotle’s four tools of dialectical reasoning. Berquist emphasizes how dialectical reasoning depends on selecting and ordering probable opinions, distinguishing word senses, identifying differences in things, and recognizing likenesses through proportion. Throughout, the lecture illustrates these logical tools through examples from mathematics, ethics, natural philosophy, and theology.
48. The Four Tools of Dialectic and Their Application #
This lecture covers the four tools of dialectical reasoning as foundational to logical inquiry: selection of probable statements, distinction of word senses, finding differences of things, and consideration of likeness. Berquist emphasizes why these tools are ordered as they are, how they exercise the mind differently, and illustrates their application through concrete examples ranging from political terminology to Aristotle’s explanation of prime matter through proportional reasoning.
49. Dialectic, Doubt, and the Discovery of Truth #
This lecture explores Aristotle’s four reasons for employing dialectical method, focusing on how doubt well-ordered leads to discovery. Berquist examines the metaphor of the ’tied knot’—how recognizing contradictions in probable arguments creates productive intellectual confusion that drives toward truth. The lecture emphasizes that dialectic is not merely a logical tool but an essential method for any genuine inquiry, with applications across natural philosophy, ethics, and theology.
50. Fallacies, Deception, and the Two Sources of Error #
This lecture examines the nature of fallacies and sophistic deception, tracing their distinction into those arising from speech (ex parte vocis) and those from things (ex parte rei) following Aristotle and the medieval commentators. Berquist explores how error originates from two fundamental sources: defects in the understanding (represented by Shakespeare’s metaphor of fog) and vices of the will (represented by filth), illustrating how these sources of deception operate in both philosophy and contemporary moral discourse. The lecture also demonstrates how proper application of the tools of dialectic—especially distinguishing word senses and identifying differences between things—serves as protection against sophistic deception.
51. The Word of God, Wisdom of Nature, and the Soul’s Immortality #
This lecture explores the relationship between the Word of God and human language as reflected in Scripture, connects the wisdom of nature to philosophical understanding through Aristotle’s natural philosophy, and examines how reason’s immaterial operations demonstrate the soul’s immortality. Berquist draws on Aristotelian philosophy, Thomistic theology, and Shakespeare to illuminate how the human soul transcends material embodiment through its capacity for understanding universals.
52. Equivocation, Amphiboly, and the Fallacy of Figure of Speech #
This lecture explores the distinction between equivocation (a single name with multiple meanings) and amphiboly (a complete speech with multiple meanings), examining how words signifying through different categories can deceive the mind. Berquist analyzes concrete examples from Shakespeare, discusses the category of relation (prosti/towards something) and its theological applications to the Trinity, and demonstrates how understanding these fallacies from speech is essential to avoiding logical and philosophical error.
53. Fallacies from Speech: Figura Dictionis and Equivocation #
This lecture explores how deception arises from the mode of speaking rather than from the nature of things themselves, focusing on the fallacy of figura dictionis (figure of diction). Berquist uses Thomas Aquinas’s analysis of how understanding and the understood are not truly like agent and patient, how the Father and Son are one beginning of the Holy Spirit, and how forms come to be—all to demonstrate how grammatical similarity can mask metaphysical difference. The central insight is that imagination, delighting in likeness, causes error when we fail to distinguish between how things are expressed and what they really are.
54. The Fallacy of Accident and Per Se Predication #
This lecture examines the fallacy of accident (fallacia accidentis), the most deceptive of all fallacies, which occurs when something is predicated of a subject accidentally (per accidens) rather than essentially (per se), yet maintains the form of a valid syllogism. Berquist explores how this fallacy deceives even wise men by involving necessary statements, analyzes multiple examples ranging from categorical predications to change and becoming, and emphasizes the crucial role of reason—properly understood as ’looking before and after’—in detecting and avoiding such deceptions.
55. The Fallacy of Accident and the Per Se/Per Accidens Distinction #
This lecture explores the fallacy of accident (fallacia accidentis), a sophisticated logical error that occurs when what belongs to something accidentally (per accidens) is treated as if it belongs essentially (per se), or vice versa. Berquist examines the distinction between per se and per accidens through analysis of Porphyry’s five predicables (genus, difference, species, property, accident) and illustrates how this fallacy deceives even the wise by involving necessary truths. The lecture demonstrates how materialism and evolutionary thinking commit this fallacy by treating what is prior in potency as prior simply.
56. Fallacies: The Accident and Simplicity versus Particularity #
This lecture concludes the study of logic by examining two critical fallacies that deceive even wise people: the fallacy of the accident (fallacia accidentis), which confuses per se and per accidens predication, and the fallacy of simplicity versus particularity (simpliciter versus secundum quid), which confuses what is true simply with what is true in a limited way. Berquist illustrates these fallacies through examples from logic, natural philosophy, rhetoric, and theology, demonstrating their serious consequences for human knowledge and conduct.
57. Simply and Somewhat: The Fundamental Distinction in Philosophy #
This lecture explores the crucial distinction between what is true simply (simpliciter) and what is true in a limited or imperfect way (secundum quid), demonstrating how confusion between these senses generates errors across ethics, politics, theology, and metaphysics. Berquist draws on examples from Solon, Aristotle, Augustine, and Thomas Aquinas to show how this distinction applies to happiness, the celibate life, laws and government, and God’s attributes like infinity and simplicity.