Aristotle

A. Introductory Remarks
B. The division of being into substance and Accident
C. Two Kinds of Predication
D. Theses about Primary and Secondary Substance
E. Lingering Questions
 

II. The Analysis of Change

A. Preliminary Remarks on Physics I
B. The Principles of Change: Matter, Form, Privation
C. Unqualified Change
D. A Problem or Two
 

III. Nature, the Four Causes, and Intrinsic Teleology

A. The Concept of Nature
B. Nature as Matter and as Form
C. The Four Causes
D. Teleology vs. Blind Spontaneity
E. Teleology in Plato and Aristole
 

IV. The Soul

A. The Soul: Form of a Living Substance
B. Kinds of Souls
C. Sensation and Intellection
D. Philosophical Anthropology:  the Immateriality, Immortality, Unicity of the Rational Soul
 

IA. Introductory Remarks

• Aristotle as student of and critic of Plato  (amicus Platonis, sed magis amicus veritatis)
• The division of logic and the philosophical sciences (see below)
• Interpreting the Categories: Things or terms?

IB. The Division of Being into Substance and Accident (preliminary framework for an account of how unqualified change is possible)

The TRANSCENDENTALS (so-called because they transcend the categories and are coextensive with being):

Every being, regardless of which category it falls into, has the following transcendental terms truly predicable of it:
 
being, one (individual or undivided), something, entity, true, good (see St. Thomas, Quaestiones disputatae de veritate, q. 1, a. 1)

The CATEGORIES: Beyond this, being, which is said in many ways, is divided into the categories:

• Substance (answers to the question, "What is it?"): that which is not present in a subject but exists per se, i.e., on its own, and not in alio, i.e., not in something else. That which is ousia, being or the really real in the paradigmatic sense.  This is the "privileged" sense of 'being' and its focal sense -- all beings in the other categories are defined by their relation to substance.  Each of the paradigmatic single members of the category of substance is a primary substance that belongs to a natural kind, a "this-such".
   
• primary substance: singular substance, e.g. Plato, Socrates, Arnie Aardvark, Ollie Oaktree, etc. (Corresponding linguistic terms: proper names of primary substances.) That which neither is said of a subject nor is present in a subject. (Note: These examples presuppose but do not prove that the really real can come into and pass out of existence. Aristotle's argument for this comes later, in the Physics.)
  
 
• secondary substance: the nature or natural kind or essence or "what it is to be a       " of a primary substance, e.g., human being, tree, tunnel spider, gold, water, etc.  (Corresponding linguistic terms: natural kind terms, including both genera and species of those genera, right down to the "lowest-level species.")  That which is said of a subject but is not present in a subject.  (The reason for saying that secondary substance is not "in a substance" will become clear below when we talk about essential predication.)  Secondary substance can also be characterized as (a) that which makes the primary substance to be a unified member of a given kind (the what it is to be of that sort of thing); (b) that which is the object of scientific knowledge (episteme); (c) that from which a thing's inseparable accidents or properties flow; and (d) the object of the so-called real definition of a thing (a definition given in terms of genus and difference -- see below).

Primary substances can be divided taxonomically into kinds (secondary substances = genera and species) by adding differences to genera at a higher level. Here is a very general taxonomy that divides substances by differences and goes from the most general genus (substance) to the "lowest-level species" human being. In each case the second member is further divided in the next level down, and all of the terms in parentheses are included in the category of substance as secondary substances:


• immaterial substance (= angel or intelligence) vs. material substance (= corporeal substance or body)
• inanimate material substance (= element/mineral) vs. animate material substance (= living substance)
• non-sentient animate material substance (= plant) vs. sentient animate material substance (= animal)
• non-rational sentient animate material substance (= brute animal) vs. rational sentient animate material substance (= human being)

Hence, the category of substance gives us a taxonomy from which theoretical inquiry can take its start.  And the purpose of such inquiry is to discover -- by reasoning from effects back to causes -- the essences and properties of primary substances.

• Accident (answers to the various forms of the question "How is it?"): that which is present in a subject and thus exists in alio, but is not said of any subject.  This is the non-primary sense of 'being'.  Each category of accidents provides the answers to various (further) questions that we can ask about a substance.  Aristotle says that accidents are not "said of" a subject because he apparently has in mind that which is designated by an abstract term, e.g., Socrates's wisdom -- which is a singular instance of wisdom and that by which Socrates is wise.  The term 'wise', on the other hand, is said of a subject and designates or signifies singular instances (tropes) of wisdom.  Here are the categories of accidents:
   
• quality: sensible characteristics of a substance (e.g., colors and sounds), shape, active and passive powers, dispositions, habits
• quantity: dimensions of a substance (continuous quantity, e.g., lines, surfaces:  the subject-matter of geometry); number (discrete quantity:  the subject-matter of arithmetic)
• relation: how a substance stands with respect to other substances (mother of, teacher of, to the left of, bigger than, etc.)
• where: place
• when: temporal characteristics
• action (acting): what a substance is doing
• passion (being acted upon): what is being done to a substance
• having: what the substance has on (e.g., clothes, makeup)
• position (or posture): how a substance's parts are ordered with respect to one another

IC. Two Kinds of Predication

• Accidental Predication: Analyzable as a (trans-categorial) relation between two singular entities, one of which (accident) has being only insofar as it is present in or inheres in or is (present) in the other (paradigmatically, a substance).  So an accidental predication presupposes that the substance in question is already constituted as a member of some natural kind.
   
• 'Socrates is wise' is equivalent to 'A (singular instance of) wisdom inheres in Socrates' (--- and not 'participates in' or 'exemplifies' the Form Wisdom).
  
  

• Essential Predication: Predication in which a species, genus, or difference (i.e., some 'secondary substance linguistic term') is predicated of a substance.
  
 
• 'Socrates is a human being' is not equivalent to 'Human nature inheres in Socrates' ........
  
 
After all, how could his human nature, which constitutes Socrates as a human being, presuppose Socrates's existence in the way an accident presupposes and depends upon the substance it inheres in?


Unanalyzability thesis: When a substance term (i.e., a species- or genus-term) is predicated of a primary substance, the resulting predication cannot be analyzed as a relation between two singular entities.

ID. Theses about Primary and Secondary Substance (from Categories, chap. 5)

• Primary Substance (PS):
 
• Every PS is a this-such, a kinded individual, an undivided unity.  (There are no "bare particulars" or "bare substances"---sorry, Anaximander)
• Every PS is an ultimate subject of predication and of accidents, but does not itself inhere in any subject.
• If no PS existed, then no accident would exist. (Note the contrast with Plato's "qualitative" Forms.)
• No PS of a given species K is more or less a substance of K than any other PS of K.
• Every PS is such that it admits of contrary accidents while remaining numerically the same PS.

• Secondary Substance (SS):
 
• An SS is said of a PS but is not present in a PS.  (It's not present in it because an SS constitutes a PS as a substance.)
• An SS exists only if it is truly predicable of some PS. (Note the contrast with Plato's "substantival" Forms, which exist whether or not they are exemplified.)
• Among the SS's, the species is more truly substance than the genus.  (It's 'closer' to the primary substance of which it is said.)
• An SS provides a privileged answer to the question "What is it?"

IE. Lingering Questions

• How is unqualified change possible, as it must be if plants and animals, which come into and pass out of existence, are primary substances and hence really real? (Physics 1)
  
 
• How can plants and animals be primary substances and hence undivided unities, given that they consist of elements and minerals? (Physics 2)

IIA. Preliminary Remarks on Physics I
 

• Method of natural philosophy:
  
 
• From what is better known to us to what is better known in itself
• From what is complex to principles and causes
• From effects to causes
 
• Basic Assumption:
  
 
• "Natural things are all or some of them subject to change" (Sorry, Zeno.)
  


• The principles of change:
  
 
• How many are there?
• What are they?

    Three descriptions of a single ordinary qualified change, where a qualified change is a change with respect to accidents (Physics 1.7):

(1) The man becomes knowing-music.

(2) From the ignorant-of-music comes the knowing-music.

(3) The ignorant-of-music man becomes the knowing-music man.

The third description is the most informative, since it makes clear the main elements, viz., (i) the contraries which serve as the formal terminus a quo or starting point (ignorant-of-music) and the formal terminus ad quem or endpoint (knowing-music) of the change, and (ii) the substance which serves as the substratum of the change. This, by the way, is Aristotle's reply to Parmenides' argument against the possibility of change.  What is comes to be in one sense from what is (the substratum with its potentiality for the new accident) and in one sense from what is not (the formal terminus ad quem). Let's look at it more carefully:

• The ignorant-of-music man becomes the knowing-music man.
  
 
• At the first level of generality we have three principles:
  
 
• ignorant-of-music = the privation from which the change proceeds.
• knowing-music = the accident toward which the change proceeds and which terminates the change.
• man = the substance which perdures through the change and is the subject first of the privation (with a potentiality for the accident) and then of the accident.
  
 
• At a higher level of generality we can see that any change (even an unqualified change, if such is possible) would have to involve three principles if it were a genuine change and not a mere succession of wholly distinct entities:
  
 
• ignorant-of-music = the privation: the absence of the perfection which will terminate the change.
• knowing-music = the form: the perfection (including, but not necessarily limited, to accidents) that terminates the change.
• man = the matter: that which serves (i) (before the change) as the subject of the privation and is in potentiality with respect to the form, and (ii) (after the change) as the subject of the form.  In other words, the matter is that which changes or is transformed.
  
 
• Notice that all three of these principles are essential. If the matter already has the form, then it cannot attain it through a change. If the matter acquires no form, then there is no change. If there is no matter or common subject of both the form and the privation, then at best we have a succession in which one matter has the privation and another--numerically distinct--matter has the perfection. But this would not be a change, strictly speaking, since there would be no common subject, even if the two distinct matters existed continuously, one after the other, in the same place. (A more interesting case would put pressure on the notion of continuity:  Suppose God were to annihilate the substance-cum-privation at t and re-create the very same substance, now with the form, at t+e, where e is a small as you please.)
  
 
• In general, then, the matter is the principle of potentiality or determinability, that which persists through the change and is the subject first of the privation and then of the form; the form is the principle of actuality or determination, that which actualizes the matter's potentiality for a given perfection.
  
 
• In qualified change, the matter of the change is a primary substance and the form is an accident. (Refer back to the list of accidents.) There are three basic types of qualified change, to which all other types of qualified change can be reduced (see On Generation and Corruption 1.4):
  
 
• alteration: change with respect to quality
• augmentation/diminution: change with respect to quantity
• local motion: change with respect to where (place)

IIC. Unqualified Change (Generation and Corruption)

Here we see the crux of Aristotle's anti-reductionistic reply to Parmenides, Empedocles, Anaxagoras and the atomists--the explanation of how real really things (ousiai) can come into existence and pass out of existence. What he has been working toward is a set of abstract concepts (a technical vocabulary, if you will) that helps us make sense of all kinds of change, both qualified and unqualified. His method in setting up this technical vocabulary is to extend his account of qualified change by analogy to the case of unqualified change.
(Note:  terminus a quo = starting point and terminus ad quem = ending point.)  There are two relevant features:

• In qualified change something complex or composite is the total terminus a quo (substance + formal terminus a quo, i.e. the privation), and something complex or composite is the total terminus ad quem (substance +  formal terminus ad quem, i.e., the accidental form).  More graphically,

 

QUALIFIED CHANGE
Total terminus a quo =	matter (the substance) +	formal terminus a quo (the privation)
Total terminus ad quem=	matter (the substance) +	formal terminus ad quem (the accidental form)

• In qualified change what is comes to be both from what is (the substance, which has the accidental form potentially) and from what is not (the privation of a form had only potentially by the substance).

The sperm and ovum become a pig (note:  Aristotle didn't have the biology exactly right, but that is irrelevant for the big claim he is making):

• The pig-sperm and pig-ovum (terminus a quo) must be thought of as a complex or composite, viz., as a subject or substratum (matter) that lacks the form by which something is a pig and has a contrary form instead -- yet with the potentiality of taking on the form by which something is a pig).
  
 
• The pig (terminus ad quem) must likewise be thought of as a complex or composite, viz., as a subject or substratum that has the form by which something is a pig.
  
 
• The matter of the change is thus something capable of "taking on" both the form by which something is a mere pig-sperm or pig-ovum and the form by which something is a pig. But notice that these forms are not accidental forms, since they are constitutive of primary substances and, unlike accidental forms, do not presuppose the existence of the relevant substance. Rather, each is a form by which something is a substance of a given type -- in other words, each is a substantial form that makes a substance to be a substance of a particular natural kind and is the source of the unity and activities that characterize substances of that natural kind as such (in this case, a living substance, a pig) -- and not just as collections of elements or of minerals, etc.  Likewise, the matter of such a change is not itself a substance but is instead something capable of becoming a substance -- even a living substance -- with its own distinctive character and principles of organization -- in other words, it is primary (or first) matter that is in potentiality to a substantial form. (We must here make a distinction between proximate matter and remote matter. This will become clearer below.)

In general, form is the principle of determination, actuality and perfection, whereas, in contrast, matter is the principle of determinability, potentiality, and perfectibility. Indeed, we can see the form/matter distinction itself as an instance of the more general distinction between act (actuality) and potency (potentiality), so that:

    A couple of notes:

• First of all, the changes in nature are ordered, so that not just any substance can be immediately generated from any other substance.  Rather, a substantial change is characteristically preceded by a series of accidental changes which prepare the way for the substantial change by rendering the substance which is the terminus a quo properly disposed for a substantial change.
  
 
• Second, Aristotle designates "first" or "primary" matter as the matter of a substantial change in order to emphasize the fact that the substantial form of a material or corporeal substance subordinates all the elements and/or minerals to the new substance in such a way that the new substance is a genuine unity (or genuine mixture of lower-level substances), with its own irreducible powers and characteristic activities, rather than a mere aggregation of independent elemental substances.  In other words, the elements entering into the constitution of a higher-level substance no longer exist as substances but have been "taken up" into the new substance and into the structures and processes which are peculiar to that new substance.  This is most evident in the case of living things, but it is nearly as evident in the case of minerals composed of elements.  The elements and minerals taken up into a living substance remain not in their substance but in their active and passive powers.  (More on this in a moment.)  Hence, even though primary matter never exists as such without any form, the unity of generated substances demands that the immediate subject of a substantial form be a matter capable of being totally "dominated by" the principle that makes a generated substance to be of a certain natural kind.  This is primary matter.
  

 

• The unity of substance (see Metaphysics, books 7-9)
  
 
• Categories: Every primary substance is a this-such, an undivided unity.
  
 
• Physics: Every (terrestrial) material primary substance is "composed of" primary matter and substantial form.

 
• Reductionism vs. emergentism (see Physics, book 2)
  
 
Are there good reasons for thinking that plants and animals are primary substances rather than just aggregates of primary substances (e.g., the elements or atoms or "seeds"), as Empedocles and the Atomists and Anaxagoras held?

• What is a nature?
  
 
• "An intrinsic source of change and staying unchanged, whether in respect of place, or growth and decay, or alteration."
  
 
• "A source and cause of change and remaining unchanged in that to which it belongs primarily and per se."
  
 

• What is nature as a whole?
  
 
A dynamic system of interacting substances endowed by their natures with active and passive causal powers and tendencies (vs. Plato's world-soul, which animates things from without). 

• What has a nature?
  
 
• Answer A: Whatever exists by nature rather than by art.
  
 
• Answer B: Anything that is a K, where <K> satisfies the following formula: Every K, as a K, has a nature
  
 
• Answer C: Every naturally occurring primary substance
  
  
  
THE BIG CLAIM (ANTI-REDUCTIONISM):
 
Minerals, plants, and animals, as such, have natures .... That is, they have intrinsic principles of change that are peculiar to them as such and that go beyond the natures of their constituents taken by themselves or as mere aggregates.  And this is just what it is to be a primary substance that belongs to a natural kind.  This entails that "bottom-up" scientific analysis and study of non-elemental substances will invariably be incomplete (though not without value); instead, such study needs to be supplemented by "top-down" synthetic considerations.
 

• Nature as matter: A substance's lower-level constituents (elements, minerals, etc.--at any level of description lower than the proper species of the relevant substance -- plug in whatever contemporary science identifies as constituents).

• Nature as form:
  
 
• The specifying powers and tendencies of the proper species as such
  
 
• Directedness toward an ideal paradigm of the species
  
 
• As noted above, one reason why substantial form is said to inform primary matter directly is that all the primary constituents are subordinated to the substantial form and cease to exist as substances in their own right. They exist, as it were, only in their powers, which are subordinated to the new higher-level substance as a unified whole.
  

IIIC. The Four Causes

• Intrinsic causes and principles of explanation as applied to natural substances:
  
 
• Material cause -- (a) the stuff out of which a substance is made, at whatever level of description (materia in quo) or (b) the stuff acted upon to effect a change (materia ex quo)  [Note:  these two notions pull apart in the case of a thing created directly ex nihilo -- it has a materia in quo but no materia ex quo]
  
 
• Formal cause -- the principle by which this stuff is constituted as a primary substance belonging to a certain lowest-level natural kind

 
• Extrinsic causes and principles of explanation:

• Efficient (agent) cause -- that which produces something by means of an action
  
 
• Final cause (teleological cause) -- that for the sake of which an effect is produced by an agent
  
 
Some examples that help us get clear about the difference between efficient and final causality:

• thermostat  (mechanism vs. goal of the operation of the mechanism)
• homeostasis (alternate mechanisms for getting to the same goal)
• normal vs. abnormal development of a living organism (both involve efficient causes, but only the former achieves the built-in aim dictated by thing's nature or substantial form)
• human action (roughly, how I did what I did vs. why I did what I did)
  
 
Aristotle: "Sometimes the formal, efficient and final causes are one." How can this be? Think of the normal growth and development of living organisms.  That growth and development are (a) effected intrinsically by parts of the substance itself [efficient cause], (b) ordered toward an end (roughly, flourishing or the good for this sort of thing) [final cause], where (c) this end is determined by the natural kind to which the substance belongs [formal cause, as in substantial form].  We will now explore the ordered nature of such change in a bit more detail.

IIID. Teleology vs. Blind Spontaneity

 Preliminary distinctions:

• Deterministic efficient cause vs. indeterministic efficient cause.  This is not what we're talking about here.
  
 
• End-oriented efficient cause vs. blind efficient cause [or, perhaps better, blind sequence of states of a system, since Aristotle denies that any efficient cause operates wholly blindly--even though some particular effects might be unaimed at or unintended by their agent causes].  This is what we're talking about here.

Two scenarios:

Scenario 1--the normal development of a red oak tree over time:

AFFFF .................................F......................>

BBGGG................................G.......................>

CCCHH................................H......................>   (a long and wonderful life for a red oak)

DDDDI.................................I.......................>

EEEEE..................................J.......................>

AFFF*F* ...............................F*
BBGGG*.................................G*
CCCHH*................................H*   (where the combination of F*, G*, H*, I*, J* = DEATH)
DDDDI*.................................I*

EEEEE.....................................J*

 

• Nature, both as a whole and in the red-oak, is wholly indifferent as regards these two scenarios. Efficient causes (if we can even talk of them on this view) or "mechanisms" work without any "directedness" in both cases, at least without any directedness at the level of living things.  So the red oak in Scenario 1 is not inherently a better or more perfect red oak than the one in Scenario 2.  There are just atoms or elements (or whatever) churning away and "producing" effects in utter stupidity and blindness in both cases.

• Complete explanations of the two scenarios can in principle be given in terms of efficient causes (or, better, blind mechanisms) alone, without recourse to teleological notions like tendency, impediment, prevention, compensation, etc.  Perhaps these complete explanations are too complicated (for now or even in principle) for human knowers to give, and so we sometimes have recourse to teleological notions to simplify things for ourselves.  But these teleological notions have no ontological significance.  That is, they don't correspond to anything distinctive in the real world.
  
 
• The "deviant" or "abnormal" is explicable wholly by recourse to mechanisms and without recourse to the "normal" defined by some mysterious goals supposedly built into living bodies. To think otherwise is just dark-age superstition.  Indeed, evaluative terms such as "deviant" or "abnormal" merely express our own preferences or interests rather than any fact about nature.
 

• Nature, both as a whole, and in the red oak, is not indifferent as regards the two scenarios. The red oak tree in Scenario 1 is a more perfect instance of red-oak-ness than the one in Scenario 2.  The natures of living things have built into them a tendency toward a norm for their species.

• In order to understand the two scenarios completely (i.e., scientifically) we must attribute various goal-directed tendencies and propensities to natures and to invoke notions like impediment, prevention, compensation, etc.  Once we understand a given nature scientifically, it is only deviant cases that require special explanation.
  
 
• What happens "always or for the most part" is indicative (though not infallibly so) of natural tendencies and propensities. What happens in nature happens because of the natural tendencies of the relevant agents.  To think otherwise is to be the victim of new-age scientistic superstition.

 

• "Laws of Nature"
  

What exactly are we saying when we say "It is a law of nature that salt dissolves in water"?  Not that every instance of salt is dissolved in water, or even that every instance of salt would dissolve if placed in water.  What, then?  How about:  Salt by its nature has a (defeasible or impedible) tendency to dissolve in salt.  The aim of science is thus to discover the natures of substances and hence their tendencies and characteristic ways of acting and being acted upon.

• Intrinsic Standards of Good and Evil
  
 
• 'This is a good tomato plant and that is a bad one'
• 'This is a good human being and that is a bad one'
  
 

Here we have the dreaded specter of Emotivism and the (alleged) Fact/Value Dichotomy vs. Aristotle's view of nature, wherein teleological standards of perfection or flourishing are built right into substances (especially living substances) by their very natures.

IIIE. Teleology in Plato and Aristotle

• Plato: The ultimate source of directedness in the physical world is extrinsic to to the physical world. (Shades of Divine Providence)
  
 
• Aristotle: The ultimate source of directedness in the physical world is intrinsic to the physical world.

Question: Are these two positions, appearances to the contrary, compatible with one another?  Stay tuned.

IVA. The Soul: Form of a Living Substance

• Distinction between two senses of actuality:
  
 
• First actuality (or First Act) = The possession of a power or set of powers
  
 
• Second actuality (or Second Act) = The exercise of a power or set of powers
  
 

• Three (more or less) equivalent accounts of the soul:
  
 
• Soul = The substance qua form (i.e., the substantial form) of a natural body that has life potentially.  ('Body' here is apparently being used here for something non-organic, i.e., some collection of elements as described in physics or inorganic chemistry.)
  
 
• Soul = The first actuality of a natural body that has life potentially.  (Same remark about 'body'.)
  
 
• Soul = The first actuality of a natural body that is organized into organs -- i.e., is an organism.  (Here 'body' is being used for an organism.)
  
 

• Salient points (neither dualism nor materialism):
  
 
• The soul is the (substantial)  form of a living thing.  A living body is not a bodily organism without its form (= soul).
  
 
• Each soul has its own proper proximate matter.
  
 
• Of all the souls of living things, only the rational soul is arguably immaterial and/or separable.
  
 
• Differences with Plato (and Descartes):
  
 
• The soul is an intrinsic, rather than extrinsic, mover of the body.
   
• The soul is ontologically constitutive of, rather than posterior to, the bodily organism.  That is, the soul is not something that is "added to" what is already a bodily substance.  Rather, the soul is the form or configuration of the matter in virtue of which this bodily substance is a tree, pig, aardvark, etc.
  
  
• Further difference with Descartes:  Plants and animals are ensouled and are not reducible to machines, i.e., not reducible to entities all of whose properties can be fully described in terms of the fundamental forces of physics or of any science below macro-biology.
  

IVB. Kinds of Souls

• Nutritive (Vegetative):
  
 
• Functions:  Nutrition, Reproduction
  
 
• Functions had by:  Plants, Brute Animals, Human Beings

• Sentient:
  
 
• Functions: Sentient Cognition (sensation, memory, imagination), Sentient Appetite (desire, pleasure, pain, fear, audacity, etc.), Locomotion
  
 
• Functions had by: Brute Animals, Human Beings

• Rational:
  
 
• Functions: Intellective Cognition (intellect: concepts, propositions, chains of reasoning), Intellective Appetite (will:  intention, consent, choice, joy, etc.).  (Aristotle has the notion of "rational desire," though not a well-developed psychology of will.)
  
 
• Functions had by:  Human Beings
  
  

What follows is a philosophical framework into which more specialized scientific information can fit, the main principle of which is that cognition must involve the union of the knower and the known, i.e., of the cognitive power and the object of cognition.

• Sensation:
  
 
• Sensation involves the alteration of the sense organs by the objects sensed.
  
 
• The objects sensed are external to the senses and act upon them to configure them in characteristic ways..
  
 
• The sensing faculty becomes like the object sensed (sensible species or likeness), and this underlies the alteration (or configuration) of the sense organ counting also as intentional, i.e., as being a type of cognition as well as a physical state of the organ.  Think of the sensible species or likeness of the object O as a certain configuration of the sense organ by virtue of which the organ is sensing-in-the-O-way.
  
 
• Sensing just is an operation of a physical or material organ, and this is why each sense is limited to a fixed range and intensity of object.

• Intellection:
  
 
• Intellection is similar to sensation in that the intellect becomes like the object which is understood. Aristotle conceives of sensation and intellection by analogy with the composition of material substances from form and matter:
  
 
• Reality: Object constituted by matter configured by form.
  
 
• Sensation: Matter* (sense organ) is configured by form* (sensible likeness corresponding to object)
  
 
• Intellection: Matter** (intellect as passive or receptive) is configured by form** (intelligible likeness corresponding to object)
  
 
• Intellection, unlike sensation, is not limited to present singular objects.  In fact, the unlimited nature of intellectual cognition is a sign that even though the higher cognitive operations of the rational soul presuppose the operation of the material powers of sensation, memory, and imagination, these higher cognitive operations are not in themselves the operations of material or bodily powers.
  
 
• Acts of the intellect: abstraction of concepts; composition and division (product:  propositions); discursive reasoning (product:  knowledge)
  
 
• The intelligible likeness (or species) is that by which the object is understood in a direct act, not that which is understood (as in representationalism, according to which the direct or immediate objects of sensation and intellection are mental objects or "ideas," to use the term used by Locke and Descartes).
  
  
• General note:  Despite what you might have heard in science classes or other philosophy classes, Aristotelians are neither stupid nor Cartesians.  They understand that brain injuries or diseases result in impaired cognitive functioning in human beings.  In fact, they explicitly assert that (in this life, at least) all cognitive functioning depends on various bodily processes, especially those involving sentience.  So you do not refute Aristotelianism by discovering that certain areas of the brain support speech, higher cognition, religious belief, etc.  To think otherwise is an ignoratio elenchi, i.e., failure to understand your opponent's position.  It's despicable, but widespread among cognitive scientists and their sympathizers.  (Fanatical philosophy majors who are really "into it" might want to check out "Good News, Your Soul Hasn't Died Quite Yet".)

IVD. Philosophical Anthropology:  Immateriality, Immortality, and Unicity of Rational Soul

• Immateriality: Intellection, unlike sensation, is not the operation of any bodily organ, even though it presupposes the operations of bodily organs in sensation, memory, and imagination.

• Immortality: Not clear what Aristotle thought.

• Unicity: Averroes takes On the Soul 3.5 to imply that there is just one intellect in both its active and passive functions. Some (Augustine at one time?) hold that there is just one active intellect, viz., an active intelligence (neo-Platonists) or God (Christians of a Platonist bent).

I. LOGIC (a necessary tool for the philosophical sciences):

• Categories: theory of terms [abstracting].
• On Interpretation: theory of propositions [composing and dividing].
• Prior Analytics: theory of syllogistic [discursive reasoning].
• Posterior Analytics: theory of demonstrative argument [science].
• Topics: theory of dialectical (non-demonstrative) argument [opinion].
• Sophistical Refutations: treatment of logical fallacy.

• Theoretical (or Speculative) Philosophy: has truth as its end, things that have principles of movement and change within themselves as its object, and analysis into causes or principles as its method.
  
 
• Natural Philosophy: has as its object things that (i) exist in matter, (ii) have matter in their definition, and (iii) are subject to one or more types of change, i.e., local motion (change in place), alteration (change in quality), augmentation (change in quantity), or generation and corruption (substantial or unqualified change).
  
 
• Physics: general principles of change and motion, causality, space and time, proof of the first mover.
• On the Heavens: principles of local motion.
• Meteorology: transmutation of the elements (chemistry).
• On Generation and Corruption: principles of alteration as ordered to substantial change
• On the Soul: general principles pertaining to things subject to augmentation (i.e., living things) (biology). 
• On Sense and the Sensible Object
• On Memory and Reminiscence
• On Sleep
• On Dreams
• On the Parts of Animals
• On the Motion of Animals
• On the Generation of Animals
  
 
• Mathematics: has as its object things that (i) exist in matter but (ii) do not have matter in their definition and (iii) are not changeable.
  
 
• First Philosophy: has as its object things that (i) do not exist in matter and (ii) do not have matter in their definition and (iii) are not changeable.
  
 
• Metaphysics
  

• Practical Philosophy: has rightly ordered action as its end, reason and appetite and their products as its object, and proceeding from causes to effects as its method.
  
 
• Nichomachean Ethics: virtue in the individual.
• Eudemian Ethics: virtue in the individual.
• Politics: virtue in the community.
• Rhetoric: theory of persuasive arguments.
• Poetics: theory of art.