12. The Three Acts of Reason and Logic's Structure

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Lecture Notes

Main Topics #

The Three Acts of Reason #

Logic is fundamentally organized around three sequential operations of reason:

1. First Act: Understanding what a thing is (simple apprehension or intelligentia indivisibilium)

   • Grasping the nature of individual things (e.g., “man,” “stone,” “animal”)
   • Sometimes called “simple grasping” because one must separate something from everything else to understand it
   • The word “grasp” is borrowed from physical grasping—just as you cannot grasp the center of a table without separating it, you cannot understand a thing without mentally separating it
   • This act is presupposed to all subsequent acts

2. Second Act: Understanding the true or the false (composition and division)

   • Making affirmative statements that put together concepts (e.g., “man is an animal”)
   • Making negative statements that separate concepts (e.g., “man is not a stone”)
   • Thomas prefers “understanding truth or falsity” because “putting together” and “separating” have multiple meanings in logic
   • Truth and falsity exist only in statements, not in simple concepts
   • This act presupposes the first act

3. Third Act: Reasoning (rationatio or “discourse”)

   • Proceeding from known truths to discover unknown truths
   • Going from multiple known statements to a new conclusion through syllogism or other arguments
   • The characteristic act of reason: coming to know what one does not know through what one does know
   • This act presupposes the second act (at least two statements are needed to reason to a third)

The Hierarchical Order of the Acts #

• Each act presupposes the previous one in strict logical order
• Without grasping what a man is and what a stone is, one cannot understand the true statement “man is not a stone”
• Without understanding at least two true or false statements, one cannot reason to a new conclusion
• Example: Understanding “every mother is a woman” and “no man is a woman” allows reasoning to “no man is a mother”

Aristotle’s Treatment in On the Soul (Book III) #

• Aristotle identifies the first two acts as operations of understanding (intelligentia)
• He calls the third operation reasoning (rationatio)
• The first act concerns “understanding of indivisibles” or simple concepts
• The second concerns “putting together and dividing”—affirmation and negation
• The third is characteristic of reason: proceeding “from the known to investigation of the unknown”

Corresponding Aristotelian Logical Works #

Thomas divides the Organon (the logical works) according to the three acts:

First Act:

• Categories (about simple concepts/names)

Second Act:

• Peri Hermeneus (Interpretatione in Latin)—about statements (affirmative and negative)

Third Act:

• Prior Analytics—about the form of arguments (whether conclusions follow necessarily from premises)
• Posterior Analytics—about the matter of arguments (whether premises are necessarily true)
• Topics—about dialectical arguments (probable reasoning)
• Rhetoric—about rhetorical arguments (persuasion through likelihood and emotional appeal)
• Sophistic Refutations—about false arguments (bad reasoning that leads astray)

The Three Tools Corresponding to the Three Acts #

Logic provides three essential tools for perfecting the three acts:

1. Definition - for the first act

   • A speech composed of multiple names that enables understanding what a thing is
   • Example: “A perfect number is a number equal to the sum of all numbers that measure it”
   • Without definitions, students cannot grasp what something is

2. Statement - for the second act

   • A speech that affirms or denies something of something
   • Makes truth and falsity possible
   • Example: “Man is an animal” (affirmative) or “Man is not a stone” (negative)

3. Syllogism/Argument - for the third act

   • A speech composed of multiple statements that enables reasoning from known to unknown
   • Example: “Every mother is a woman; no man is a woman; therefore, no man is a mother”

The Acts as End; the Tools as Subject Matter #

• When discussing what logic is about, we refer to the three acts (the purpose or end of logic)
• When discussing the subject matter of logic, we refer to the three tools (definitions, statements, arguments)
• Logic is analogous to eyeglasses or microscopes: these are tools that perfect and enable the act of seeing
• Logic provides and examines the tools that perfect and order the acts of reason

Logic as Tool of Philosophy #

• Logic is not a principal part of philosophy but a tool that serves all other sciences
• Unlike the speculative sciences (mathematics, natural philosophy, metaphysics), logic is not pursued for knowledge of its own subject matter
• Rather, things studied in logic “are not sought to be known for themselves, but as a help to the other sciences”
• Logic provides the definitions, statements, and arguments necessary for all other knowledge
• Logic is sometimes called more a “tool of science” than a science itself (following Boethius)
• It is the “art of arts” because it directs reason itself, which directs all other arts

Key Arguments #

The Necessary Hierarchical Order #

• Premise 1: The first act (understanding what a thing is) is necessary before one can make any affirmative or negative statement

• Premise 2: One cannot understand a true statement without having first grasped the terms involved

• Conclusion: The first act is ordered to (presupposed by) the second act

• Example: If students don’t know what a “perfect number” or “composite number” is, they cannot understand the statement “a perfect number is a composite number”

• Premise 1: The second act (understanding truth/falsity) is necessary before one can reason

• Premise 2: Reasoning requires at least two known statements from which to derive a third

• Conclusion: The second act is ordered to (presupposed by) the third act

Why Logic Must Examine All Three Acts #

• Premise 1: Logic is the “science of reason”
• Premise 2: Reason operates through these three acts
• Conclusion: Logic’s consideration must extend to all three acts and the things pertaining to them
• This is why Thomas divides Aristotle’s logical works according to the three acts

The Gradation of Arguments #

Following Plato’s analogy in the Phaedo, arguments exist in a hierarchy:

• Demonstration (Prior and Posterior Analytics): Arguments you can trust completely

  • Produce certitude of knowledge
  • Require both valid form and necessarily true premises

• Dialectical Arguments (Topics): Arguments you can trust up to a point

  • Produce opinion or belief
  • Built from probable premises (opinions of all men, most men, or the famous)
  • Reason turns wholly to one side of a contradiction, though with some fear of the other

• Rhetorical Arguments (Rhetoric): Arguments you can trust even less

  • Produce suspicion rather than full opinion
  • Based on likelihood and emotional appeal
  • Reason is more inclined to one side than the other, but not wholly
  • Include representation and poetic arts

• Sophistic Arguments (Sophistical Refutations): Arguments you cannot trust at all

  • Simply bad arguments that lead astray
  • Based on fallacies and defects of reasoning

This mirrors nature: some things happen always necessarily (like the sun rising), some most of the time (like healthy babies), and some fail (producing something defective).

Important Definitions #

Definition (definitio) #

A speech composed of multiple names that signifies what a thing is. Example: “A square is an equilateral right-angled quadrilateral.” Each part has meaning by itself, and the whole depends on the parts.

Statement (enuntiatio) #

A speech that affirms or denies something of something, thereby making truth or falsity possible. Example: “Man is an animal” (affirmative) or “Man is not a stone” (negative).

Syllogism (syllogismus) #

A speech in which certain statements being laid down, another statement follows necessarily because of those that were laid down. Example: “Every mother is a woman; no man is a woman; therefore, no man is a mother.”

Simple Apprehension (intelligentia indivisibilium) #

The first act of reason: grasping or understanding what a thing is without affirming or denying anything about it. Also called “simple grasping.”

Composition and Division (compositio et divisio) #

The second act of reason: putting together (affirmation) or separating (negation) concepts in statements.

Discourse (discursus) #

The characteristic act of reason: coming to know what one does not know through what one does know. A “looking before and after” to see the order of causes and effects.

Reason (ratio) #

The ability for discourse—for moving from one thing to another to come to knowledge of the unknown through the known.

The Organon #

Greek word for “tool.” The collective title for Aristotle’s logical works, which serve as the tool of philosophy.

Examples & Illustrations #

Understanding Through Definition #

If a student doesn’t know what a “perfect number” is, Berquist provides the definition: “A number equal to the sum of all numbers that measure it.” The first perfect number is 6 (measured by 1, 2, and 3; and 1+2+3=6). Four is not perfect (measured by 1 and 2; but 1+2=3, not 4). Without this definition, students cannot grasp what a perfect number is, and therefore cannot understand statements about perfect numbers.

Similarly, without understanding what a “composite number” is (a number measured by itself and some other number), one cannot understand that “a perfect number is a composite number.”

The Table’s Center and Grasping #

You cannot grasp the center of a table while it is intact because you cannot separate it from the rest of the table. But if you take a saw and cut out that piece, then you can grasp it. This illustrates what it means to understand something: you must be able to separate it conceptually from everything else.

Wine Tasting and Judgment #

Wine judges are given blind tastings (without seeing the bottle label) to properly judge quality. If they don’t know what wine they’re tasting, they cannot properly distinguish between wines and judge their relative worth. Similarly, one must first understand what things are before making true or false statements about them.

The Stepmothers in Fairy Tales #

Children fear stepmothers because fairy tales represent them as cruel, not because of actual experience. This shows how representation influences our conclusions. This is why poetic arts can be dangerous if they present immoral actions in an attractive way, and why they belong to logic in a broad sense—they lead people to conclusions through representation.

Othello and Iago #

Iago persuades Othello that his wife is unfaithful through:

1. Projecting himself as a trustworthy friend
2. Appearing observant and hesitant to state suspicions
3. Working on Othello’s emotions (arousing jealousy)
4. Providing weak evidence (the handkerchief) that seems convincing to a jealous mind

Iago himself notes: “To a man who’s in this state of mind now, this jealousy, even a flimsy proof will seem like sacred scripture to him.” This illustrates how rhetoric uses arguments, character projection, and emotional appeals to persuade.

Demosthenes’ Political Rhetoric #

Demosthenes made fun of his opponent for scrubbing benches as a young man, implying he was a nobody from no noble family. This was effective rhetoric in aristocratic Greek society. However, the same rhetoric would be ineffective today in a democratic society that admires the self-made man. A speaker must know the forms of government and customs studied in political philosophy to be persuasive to different audiences.

The Uncle Tom’s Cabin Example #

This novel persuaded many people against slavery through representation, not through formal arguments. This shows how poetic arts, through representation rather than logical argument, can lead people to conclusions—which is why poetics belongs to logic in a broad sense.

Notable Quotes #

“And I understand what a stone is, I might separate them in a negative statement and say, man is not a stone, right? And I’d be understanding something, what, true, right?”

“If I didn’t understand in some way what a man is, and I didn’t understand in some way what a stone is, I wouldn’t understand the true statement that man is not a stone, right?”

“So, you can see how this first act is presupposed to the second, then.”

“The operation of the understanding is twofold… One which is called the understanding of indivisibles… the understanding of indivisibles or the incomplex by which it conceives what a thing is.”

“Grasping is another word almost for understanding. I can grasp this glass, because I can separate the glass from the air around it. But I can’t grasp the center of this table, because I can’t separate the center of this table here from the rest of the table.”

“Unless I’ve grasped in some way what a man is, right? Unless I’ve understood in some way what a man is, and I’ve grasped also in some way what an animal is, right? And understood in some way what an animal is. Unless I’ve done that first, I couldn’t really, what? Put them together and understand what it means to say man is a, what? Animal, right?”

“So that first act, in a way, is ordered to the second act.”

“The things however which logic is about are not sought to be known for themselves, but as a help to the other sciences.”

“Logic is called the tool of philosophy.”

“And organon is a Greek word, or we get our word organ, by the way, huh? Organon, organon is simply the Greek word for tool, okay?”

“There is another, however, proceeding of reason, in which the true is for the most part concluded, not, however, having necessity. And the third proceeding of reason is that in which reason departs from the true, because the defect of some principle that should have been observed in reasoning.”

“Arguments are like people. There are few arguments you can trust, what, completely. There are some arguments you can’t trust at all. Most arguments are in between.”

Questions Addressed #

Why is the order of the three acts important? #

Berquist demonstrates that each act logically presupposes the previous one. Without understanding what things are (first act), one cannot make true or false statements about them (second act). Without at least two understood statements, one cannot reason to a new conclusion (third act). This hierarchical order is not arbitrary but reflects the structure of human reasoning itself.

How do definitions serve understanding? #

Definitions are necessary tools for grasping what things are. When students don’t know what a “perfect number” is, the definition enables understanding. The definition allows one to “separate” the thing conceptually from everything else, which is what understanding requires. Without definitions, students cannot grasp the nature of things and therefore cannot proceed to make true statements about them.

Why do truth and falsity exist only in statements? #

Berquist points out that simple concepts like “man,” “stone,” or “animal” are neither true nor false. Truth and falsity only become possible when concepts are put together or separated in statements. When one affirms “man is an animal” or denies “man is a stone,” the statement is either true or false. This is why the second act (composition/division) is necessary before one can evaluate the truth or falsity of claims.

How do Aristotle’s logical works correspond to the three acts? #

Thomas divides the Organon according to which act each work addresses: the Categories addresses the first act (simple concepts); the Peri Hermeneus addresses the second act (statements); and all the remaining works address the third act (reasoning), subdivided into demonstration (Prior and Posterior Analytics), dialectical arguments (Topics), rhetorical arguments (Rhetoric), and bad arguments (Sophistical Refutations).

What is the relationship between the acts and the tools? #

The three acts of reason are the end or purpose of logic. The three tools (definition, statement, syllogism) are the subject matter of logic. Logic perfects and orders the acts by providing and examining the tools. This is analogous to how eyeglasses or microscopes enable and perfect the act of seeing without being themselves an act of seeing.