49. Necessity, Per Se, and the Four Tools of Dialectic

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Lecture Notes

Main Topics #

The Connection Between Necessity and Per Se (Kath’auto) #

• Necessary truths are those that belong to a thing “as such” or “through itself” (per se in Latin, κατ’αὐτό in Greek)
• Whatever pertains to a thing’s definition belongs to it necessarily and as such
• Examples:
  • A triangle being a rectilineal plane figure belongs to it as such (part of definition)
  • A triangle having interior angles equal to two right angles belongs to it as such (follows necessarily from what a triangle is), though not part of the definition
  • A triangle being green does NOT belong to it as such (neither defines it nor follows from its nature)
• A property in the strict sense belongs only to a thing, to every instance of it, and always
• Aristotle establishes a reciprocal relationship: if something is necessary, it belongs to a thing as such, and conversely, if it belongs as such, it is necessary
• The nature of a thing (what it is) is first in that thing; you must be what you are before you can be anything else

The Role of Definition in Understanding Necessity #

• Definition makes known what a thing is (the nature of the thing)
• Once a nature is made known clearly through definition, one can see what follows necessarily upon that nature
• If the nature is not understood clearly enough, one may not see what follows from it
• Example: Knowing a triangle is defined as a rectilineal plane figure contained by three straight lines allows one to demonstrate that its interior angles equal two right angles

Demonstrative vs. Dialectical Syllogisms (Review) #

• Demonstration: Takes one half of a contradiction as necessarily true and excludes the other as manifestly false; leads to necessary conclusions
• Dialectic: Gives a choice between probable alternatives without claiming necessity; both sides can appear probable
• Sophistical syllogism: Appears to be a good dialectical syllogism but is not
• Both demonstration and dialectic are “good” forms of reasoning but serve different purposes

Dialectical Arguments: Syllogism and Induction #

• The dialectician uses two forms of argument: dialectical syllogism and induction
• Induction: Does not demonstrate that something must be so; establishes probability
  • Example: Cutting open a thousand frogs with three-chambered hearts does not prove all frogs must have three-chambered hearts
  • Produces universal statements based on observation but without necessity
• In some cases, understanding the nature of terms allows one to move from inductive experience to necessary knowledge
  • Example: Understanding what a whole and part are allows us to see necessarily that a whole is larger than its part
  • Example: Understanding odd and even numbers allows us to see necessarily that no odd number can be even
• Contrast with rhetoric: Rhetoric uses enthymeme and example (for singular, contingent matters); dialectic uses syllogism and induction (for universal matters)

The Four Tools of the Dialectician #

First Tool: Selecting Probable Premises #

• A probable opinion (probabilis) is:
  • An opinion held by all or most men
  • An opinion held by all or most men in a given art or science
  • An opinion held by the most famous and illustrious men in an art or science
• Probability derives from either quantity (how many hold it) or quality (how famous/authoritative those who hold it are)
• Requires recognizing what constitutes a probable statement
• Involves dividing probable opinions according to subject matter:
  • Natural philosophy (opinions about nature)
  • Logic (opinions about reasoning and language)
  • Ethics and political philosophy (opinions about choice, avoidance, and human conduct)
• Requires ordering opinions from general to particular:
  • Most general opinions influence all subsequent thinking in that field
  • Example in ethics: Understanding what “good” means is foundational to all ethical reasoning
  • One cannot properly reason about justice, courage, or temperance without first clarifying the concept of good
• Finding the most basic opinion of a thinker (especially if expressed as a definition) reveals what will influence all his other thinking
  • Example: If a man thinks “philosophy is the search” rather than discovering truth, this shapes all his subsequent philosophical method
• The ability requires both general experience with men and particular experience with men in specific fields

The Importance of Ordering Opinions: The Example of “Good” #

• The first definition of good: “good is what all desire” or “what all want”
• Socratic question: Do we want something because it is good, or is it good because we want it?
• The correct answer: We want it because it is good (not vice versa)
• If a man believes “something is good because we want it,” this false opinion will influence all his thinking about ethics
• Demonstrating this requires simple examples showing that what we want is not always good for us:
  • The extra drink at a party—what was wanted became recognized as not good
  • The reckless driving example—the youth wanted to drive fast but later recognized it was not good for him
• Once established that something is not good because we want it, one can then argue that something is not better because we want it more
• This foundational clarity allows proper reasoning about whether souls’ goods are better than body’s goods (Socrates vs. Athenians in the Apology)
• Similar ordering applies in political philosophy: Man is by nature a political animal → society is necessary → various forms of government → particular political questions

Key Arguments #

The Reciprocal Nature of Necessity and Per Se #

1. If necessary, then as such: Whatever belongs to a thing necessarily belongs to it as such (through its nature)
2. If as such, then necessary: Whatever belongs to a thing as such belongs to it necessarily
3. The nature is first: The nature of a thing (what it is) is what is first in that thing ontologically and epistemologically
4. Implication: The natural road (sensory to rational knowledge) and the first road (understanding what a thing is) are convertible because they both lead to understanding the nature

Demonstration from Nature through Definition #

1. Starting point: A thing’s definition makes known its nature
2. Necessity: From understanding the nature, necessary consequences follow
3. Example chain:
   • Definition: A triangle is a rectilineal plane figure contained by three straight lines
   • Consequence 1: It is necessarily a plane figure (part of definition, so per se)
   • Consequence 2: It is necessarily contained in a plane (follows from being plane)
   • Consequence 3: Its interior angles necessarily equal two right angles (follows from the nature of triangles and parallel lines)
4. Non-necessary properties: What does not follow from the definition cannot be demonstrated as necessary
   • Example: A triangle being green cannot follow from its definition, so it cannot be demonstrated

Probability without Necessity in Dialectic #

1. Induction’s limitation: Even repeated observations (a thousand frogs with three chambers) establish only probability, not necessity
2. Why: Induction covers only finite cases, not the infinite or essential nature
3. Exception: When the definition or nature is known clearly enough, induction can lead to necessary knowledge
4. Difference from demonstration: Dialectic aims at probable truth; demonstration at necessary truth

Important Definitions #

Per Se / As Such (κατ’αὐτό / per se) #

That which belongs to a thing through its nature or definition; what necessarily follows from what a thing is. Contrasts with accidental properties that happen to belong to a thing but do not flow from its nature.

Probable Opinion (Δόξα / opinio probabilis) #

An opinion that derives probability from being held by all or most men, or by the most famous and authoritative figures in a given field of knowledge. The foundation of dialectical reasoning, distinct from necessary truth known through demonstration.

Natural Road vs. First Road #

Two convertible paths to knowledge: the natural road (advancing from sensory experience to rational understanding) and the first road (understanding the nature of a thing as what is first in that thing). Both lead to grasping what a thing is.

Examples & Illustrations #

Triangles and Necessary Truths #

• Green triangle: A triangle might be green, but being green does not belong to triangles as such (not in definition, does not follow necessarily from triangle-nature). Therefore, one cannot demonstrate that a triangle is green; one can only observe it through the senses.
• Interior angles equal two right angles: This belongs to a triangle as such (follows necessarily from its nature), even though it is not part of the definition. A geometer can demonstrate this by showing how a line parallel to one side creates equal alternate angles that sum to two right angles.
• Spherical triangles: Drawing a triangle from the North Pole down to the equator and back creates a figure with more than two right angles in the sum. This is equivocation on the word “triangle”—it is not a plane figure, so the rule for plane triangles does not apply. One must use the word “triangle” univocally (understanding it always as a plane figure) for the necessary property to hold.

Snow and Probability #

• Observable whiteness: Snow appears white to us, and all snow we observe is white
• Inductive probability: From seeing white snow, one might inductively conclude all snow is white
• Lack of necessity: We do not see that whiteness belongs to snow as such (we do not understand the nature of snow well enough to know it must be white)
• Hypothetical counterexample: If someone reported green snow on Mars, we would be surprised but would not say it is impossible (unlike saying a non-right-angled triangle is possible)
• The principle: Without understanding why snow must be white (its nature), we hold the opinion as probable, not necessary

The Extra Drink at the Party #

• A guest accepts another drink from the host
• After consuming it, the guest recognizes: “one too many”
• Demonstrates: What we wanted (another drink) was not actually good for us
• Conclusion: Something is not good because we want it; rather, we want it because (or insofar as) it is good
• Implication: Challenging the foundational error that “good = what we desire” undermines all subsequent mistaken ethical reasoning

The Reckless Driver #

• A young man wants to drive his car at one hundred miles per hour down a curvy road
• He crashes into a tree
• Even he recognizes: It was not good for him to drive so fast, despite wanting to do so
• Significance: Even the agent himself can see the disconnect between wanting something and that thing being good for him

Homo Sapiens vs. The Naked Ape #

• The Naked Ape: A book title referring to humans; suggests nakedness (lack of fur) as a distinctive feature
• Scientific inaccuracy: Compared to apes, humans have less fur relative to body size, but humans are not “naked”
• Correct naming: Homo sapiens (the wise ape) properly identifies humans by their distinctive nature—reason or the excellence of reason
• Significance: “Sapiens” names the distinctive excellence (wisdom as the highest perfection of reason) rather than a superficial physical feature
• Connection to the lecture: Wisdom names the chief good or greatest perfection of reason; therefore, one who loves wisdom (the philosopher) must love reason itself

Philosopher’s Love of Reason and Wisdom #

• Question: Must a philosopher love reason? Must a philosopher love popcorn?
• Definition: A philosopher is defined as a lover of wisdom (φιλοσοφία = love of wisdom)
• Wisdom defined: Wisdom names the highest or greatest perfection of reason
• Necessary connection: If one loves wisdom (the chief good of reason) and wisdom is the excellence of reason, then one must love reason itself
• Analogy: Just as one cannot love health (the good of the body) without loving one’s body, one cannot love wisdom (the good of reason) without loving reason
• Application to man: Man is defined as an animal with reason; therefore, if man does not love reason, he does not love himself; if he does not love the good of reason (wisdom), he does not love himself
• Application to angels: Angels have understanding (immediate grasp of truth) rather than reason (discursive thinking). An angel naturally loves truth and wisdom, which is why fallen angels are tormented (unable to see God) and souls in purgatory are anxious to see God face to face

Notable Quotes #

“The demonstrator, right, he takes one half of a contradiction and lays it down as necessarily true, right? And excludes the other half, right? Discards the other half as manifestly false, right? The dialectician, in the concrete, in his conversation with other man, he gives you, what? A choice, right?”

“What something has through being itself, through being what it is, right? Obviously belongs to it, through itself, or as such, right?”

“One could never reason out that a triangle must be green, right? One could reason out that a triangle has its interior angles, it’s either the right angle. Because that is a necessary connection to what a triangle is.”

“If the nature is not understood clearly enough, you might not see what follows from it.”

“If something is good because you want it, and everything you wanted was good for you, wasn’t it?”

“You must be what you are before you can be anything else.”

Questions Addressed #

What is the relationship between necessity and per se (as such)? #

Answer: They are reciprocally related. Whatever belongs to a thing necessarily belongs to it as such (through its nature), and conversely, whatever belongs to a thing as such belongs to it necessarily. This connection is fundamental because the nature of a thing is what is first in that thing—you must be what you are before you can be anything else.

How does understanding the nature of something (through definition) enable demonstration of necessary truths? #

Answer: A definition makes known what a thing is. Once the nature is made clear through definition, one can see what follows necessarily upon that nature. For example, once we understand a triangle as a rectilineal plane figure, we can see that its interior angles must equal two right angles. If the nature is not understood clearly enough, one may not see what follows from it.

What is a probable opinion, and how does it differ from necessary truth? #

Answer: A probable opinion is one held by all or most men, or by the most famous and authoritative figures in a field. It derives probability from the quantity or quality of those holding it, not from necessity inherent in the nature of things. Necessary truths belong to a thing as such and are demonstrated through definition and logical consequence; probable opinions are held on the basis of observed frequency or authority but without the certainty of necessity.

Why must the dialectician begin by selecting probable premises according to subject matter and ordering them from general to particular? #

Answer: Because opinions are expressed in words and require understanding within a specific field (natural philosophy, logic, ethics, politics). More fundamentally, the most general and basic opinions influence all subsequent thinking in that field. For instance, understanding what “good” means is foundational to all ethical reasoning about justice, courage, and temperance. By ordering opinions from general to particular and identifying the most basic ones (especially definitions), the dialectician can select the premises that will be most influential and relevant to the inquiry.

Can induction alone establish necessary truth? #

Answer: No. Induction by itself establishes only probability. Observing a thousand frogs with three-chambered hearts does not prove that all frogs necessarily have three-chambered hearts. However, when combined with understanding the nature of things through definition, induction can lead to necessary knowledge. For example, understanding what a whole and part are allows us to see necessarily (not just probably) that a whole is larger than any of its parts.

Why is it important that one carefully distinguish whether something is good because it is wanted, or whether it is wanted because it is good? #

Answer: This distinction is foundational to ethics. If something is good only because it is wanted, then there is no objective standard for “better”—something would be better only if wanted more. This false opinion corrupts all subsequent ethical reasoning. Once one establishes (through concrete examples like the extra drink) that what we want is not always good for us, one can properly argue that the goods of the soul are genuinely better than the goods of the body, not merely because we want them more, but because they are objectively superior goods.