Aristotle: Reason, Logic, & Ethics

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Doctrines & Discoveries

Notes & Quotes

Reason: the Intellect




- know how

- wisdom





- induction

- deduction


“But since Aristotle did not allow that forms of natural things exist apart from matter, and as forms existing in matter are not actually intelligible; it follows that the natures of forms of the sensible things which we understand are not actually intelligible. …  We must therefore assign on the part of the intellect some power to make things actually intelligible, by abstraction of the species from material conditions. And such is the necessity for an active intellect.”


Review: psyche -- soul -- the form/functioning of the body

Vegetative faculty: insofar as it lives (i.e., takes nourishment, strives to reproduce, etc.)

sensitive faculty: insofar as it senses (i.e., reflects the sensible forms from things round about it for the purposes of navigating its environment):

intellectual faculty (aka mind or reason): insofar as it conceives and judges (reflects the intelligible forms of things)

Issue concerning the difference between sensitive (e.g., in eyes) and nonsensitive reflection (e.g., in mirrors) of "sensible forms": a kind of uptake by intelligence must be added?

“But smelling is more than such an affection [as of the air] by what is odorous -- what more?  Is not the answer that, while the air owing to the momentary duration of the action upon it of what is odorous does itself become perceptible to the sense of smell, smelling is an observing of the result produced?”  (Aristotle, On the Soul ii:12)


"[W]e can dismiss as unnecessary the question whether the soul and the body are one: it is as meaningless as to ask whether the wax and the shape given to it by the stamp are one, or generally the matter of a thing and that of which it is the matter."

Controversy about the "active intellect" (430a17ff)

"When [active reason] has been separated it is that only which it is in essence, and this alone is immortal and eternal.  We do not remember, however, because active reason is impassible, but the passive reason is perishable, and without active reason nothing thinks.

Genesis of Reason out of Sensation

Lower faculties not encapsulated: vegetative and sensitive functions are mediated by the cognitive

Reason is beholden to sensation (as form to proximate matter)

thought the form of forms (uses sensory and intellectual images)

sense -> memory -> experience (habit) -> skill (expert habit) &  knowledge

"Thus it is clear that we must get to know the primary premises by induction; for the method by which even sense perception implants the universal is inductive."

Nature of Reason

Conception: "thinking of the simple objects of thought is found in those cases where falsehood is impossible"

Judgment: "where the alternative of true or false applies, there we always find a putting together of objects of thought in a quasi-unity"

Segue: Logic, the science of reasoning; ideal of correct reasoning illuminates what is reasoning: things are known by their working & their power.

1.        "[Perception] of the special objects of sense is always free from error, and is found in all animals, while it is possible to think falsely as well as truly, and thought is found only where there is discourse of reason as well as sensibility."

2.        "[S]ince everything is a possible object of thought, mind . . . must be pure from all admixture . . . can have no nature of its own, other than that of having a certain capacity."

3.        "[T]he soul is analogous to the hand; for as the hand is a tool of tools, so the mind is the form of forms and sense the form of sensible things."

4.        "Since according to common agreement there is nothing outside and separate in existence from sensible spatial magnitudes, the objects of thought are in the sensible forms, viz. both the abstract objects and all the states and affections of sensible things.  Hence (1) no one can learn or understand anything in the absence of sense, and (2) when the mind is actively aware of anything it is necessarily aware of it along with an image; for images are like sensuous contents except that they contain no matter."

5.        "So out of sense-perception comes to be what we call memory, and out of frequently repeated memories of the same thing develops experience; for a number of memories constitute a single experience.  From experience again -- i.e., from the universal now stabilized in its entirety within the soul, the one beside the many which is a single identity within them all -- originate the skill of the craftsman and the knowledge of the man of science, skill in the sphere of becoming and knowledge in the sphere of being."

6.        “The case of [active] mind is different; it seems to be an independent substance implanted within the soul and to be incapable of being destroyed.”

Logic: Science of Inference

Square of Opposition




Inference: combination of judgments to arrive at further judgments

Premises and Conclusions

combined judgments are called premises {3}

the judgments arrived at are called conclusions

Correctness of Judgment = Truth

Correctness of Inference: Truth Preservation

Standard of deductive Validity: Truth of the premises guarantees the truth of the conclusion

If the premises are true, so must the conclusion be.

There are formal principles of validity:

Syllogistic: articulates such principles holding for certain inferences: i.e., those involving

three categorical judgments (or propositions) {3}

 two premises

one conclusion

with three terms -- names of individuals or univocal predicates each occurring twice.

Correspondence Theory of Truth {1}

Laws of Thought: Contradiction; excluded middle.


1.        "To say of what is that it is, or of what is not that it is not, is true; to say of what is that it is not, or of what is not that it is, is false."

2.         “Things are said to be named `equivocally’ when though they have a common name, the definition corresponding to the name differs for each.  …  On the other hand things are said to be named `univocally’ which have both the name and the definition … in common.”

3.        ”A premiss then is a sentence affirming or denying one thing of another. This is either universal or particular or indefinite. By universal I mean the statement that something belongs to all or none of something else; by particular that it belongs to some or not to some or not to all; by indefinite that it does or does not belong, without any mark to show whether it is universal or particular, e.g. 'contraries are subjects of the same science', or 'pleasure is not good'.”

4.        "It is impossible for the same thing to be and not to be."
























But to feel [and do things] at the right times, with reference to the right objects, towards the right people, with the right motive, and in the right way, is what is both intermediate and best, and this is characteristic of virtue.



Naturalism: the good is that at which all things aim.

Relativity of Good: what's good is self-actualization: which depends on the kind of "selves" concerned: good paperweights are bad kites

No Univocal Form of the Good (no single concept the word "good" expresses).  Goodness relative to Type (like "large").  This is a kind of ambiguity (compare the "bank" argument).  The argument below commits the fallacy of four terms because it equivocates on "small": small(1) = "for and elephant", small(2) = "for an animal" {1}

Dumbo is a small elephant

Elephants are animals

Dumbo is a small animal 

Aristotle's Ethics Seeks the Human Good {6}

The human good can be adduced from actual human pursuits, naturally.

WTJ: The good for any thing is that which truly satisfies that thing.  {9}

this final satisfaction = the things aim or purpose {5}

The chief human good is happiness {7}

an inclusive good: the addition argument

activity in accordance with virtue {8}

virtue is a mean between excess and deficiency

doing with regard to specific human activities

it's (an art of) doing

to . . .the right person

to the right extent

at the right time

with the right motive

in the right way

as sense guided by reason (especially habits formed under the tutelage of reason) determines.

Practical Syllogism

MAJOR PREMISE (re: the principle): Such is best.

MINOR PREMISE (re: the particulars): This is such.

CONCLUDING ACTION: Therefore, I do this “forthwith”.

Case of Weakness of the Will (Incontinence) {2}{3}

To quit smoking is best. {10}

Not lighting now would be quitting

Nevertheless, I light up forthwith.

Analysis: moved by immediate isolated appetite (for a smoke, now) rather than comprehensive wish (for long run health & happiness).

Gimme smoke.

Lighting up now would be smoking.

Forthwith, I light up.

Wish: rational appetite: determines the end to be pursued


comprehensively: what's best all things considered.

Choice & Deliberation {11}

what deliberation decides to be the best means to our end

we choose

some acts are voluntary but not deliberate

The highest human activity is speculative thought: contemplation. {8}

1.      "The good then is not some common element answering to one idea."

2.       "[ M]ind is never found producing movement without appetite (for wish is a kind of appetite; and when movement is produced according to calculation it is also according to wish), but appetite can originate movement contrary to calculation, for desire is a form of appetite."

3.      "I want to drink, says appetite; this is drink, says sense, or imagination or thought.  Straightaway I drink."

4.      "[T]hat which appears good to the good man is thought to be really so."

5.      "Every art and every inquiry, and similarly every action and pursuit, is thought to aim at some good; and for this reason the good has been rightly declared to be that at which all things aim."

6.   "If then there is some end of the things we do, which we desire for its own sake (everything else being desired for the sake of this), and if we do not choose everything for the sake of something else (for at that rate the process would go on to infinity, so that our desire would be empty and vain) this must be the good and the chief good."

7.   "[Happiness] we choose for itself and never for the sake of something else, but honor, pleasure, and reason, and every virtue we choose indeed for themselves (for it nothing resulted from them we should still choose each of them), but we choose them also for the sake of happiness, judging that by means of them we shall be happy."

8.   "[A] clearer account of what [happiness or the chief good] is . . . might perhaps be given if we could first ascertain the function of man."

9.   "[F]or all things that have a function the good and the "well" are supposed to reside in that function, so too it would seem for man."

10.  "The use of language by incontinent men means no more than its utterance by actors on the stage."

11.  “That which is the object of appetite is the stimulant of [deliberation] and that which is last in the process of thinking is the beginning of the action."



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