Notes on Aristotle’s “Physics”

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Book I

Chapter 1

Physics studies the causes and principles of natural beings, those things that change in space and time.

[“Cause” and “principles” defined:]

I post this link because both of these words are significantly different in Greek from English.

Cause” (“aitia”) can mean either of the following:

  1. The normal sense of “cause”, which is some event or thing that affects itself or something else and effects some change in space or time.
  2. An “explanation”, which is a set of propostions of mental content that refers to either;
    1.  A “cause” in the sense given just above (#1),
    2. Or a cause in the sense of another propostion or other mental content.
    3. Or some sort of “law of nature”. (Note that it is hard to know what sort of thing a “natural law” is; it could fall under either of the above sense of “cause” or as some mixed case, or we could just forego answering this question and leave it as a third sort of “cause”.)

“Beginning/ principle” (“arche”) also has a similar ambiguity of meaning, being either

  1. Some sort of rule, law or other mental content
  2. Some actual thing that does something to effect change or perhaps even prevent some change,
  3. The nature of reality itself.
  4. A ruler / leader / or law-giver.
  5. The foundation of a building.
  6. A goal which was the cause of taking some action or an event that motivated some action on the part of some agent as a reaction,  Aristotle uses the example of an insult being the arche of a fight.

There are very very many cases in the works of Aristotle where ambiguiuty in the meanings of these and many other words will create confusion in the reader. Another famous case isthe use of “happiness” to translate “eudaimonia” You may as well get used to it, because this is just a fact of life when you are reading a translation of an author from a distant culture. Similar problems occur with translations from Chinese (look us “Tao“), Sanskrit (see “Dharma“), and other languages. There is no way around this, but it is a great way to free your mind from the tyranny of grammar and parochial assumptions concerning the fundamental nature of reality. If I have made this point for you, I encourage you to go back and read the above-linked work (“Metaphysics Book V”) and read the definitions of “cause” and “beginning / principle” so that you can get it from Aristotle himself. Then, scan the rest of the definitions, especially “elements” and “beginning” (which is actually how this translator translated “arche“, which is just something you will have to get used to when reading Aristotle.)

I just skimmed over Book I, and have taken note of the most interesting parts of it. I would prefer to focus on Book II. Because of this, I recommend that you skip straight to “Book II – What is nature?” below.

Q: How many elements are there, Aristotle?
A: Either two or three.

This is one of the many parts of the Physics that are primarily of historical value; if you can restate the arguments found here in a modern form, that would be great. But this chapter is mostly of interest in the way he goes about getting his answers.

“The principles in question must be either (a) one or (b) more than one. If (a) one, it must be either (i) motionless, as Parmenides and Melissus assert, or (ii) in motion, as the physicists hold, some declaring air to be the first principle, others water. If (b) more than one, then either (i) a finite or (ii) an infinite plurality. If (i) finite (but more than one), then either two or three or four or some other number. If (ii) infinite, then either as Democritus believed one in kind, but differing in shape or form; or different in kind and even contrary.” (Physics I.2)

Number of Principles

  1. One Principle
    1. Motionless (Motion merely apparent, not “really real”(onto on).)
      1. Zeno, Parmenides, Melissus
      2. Don’t even bother with these people.
        1. They deny the reality of change.
        2. Aristotle has already proven in his “Categories” and “Metaphysics” that
          1. change is possible and
          2. that changeable things are knowable.
        3. Thus the premise “There is change.” can be allowed into First Philosophy on the strength of our experience.
    2. In motion
      1. Urstoff
      2. Tao
  2. Many
    1. Finite in number
      1. 2 in number
        1. Yin/Yang
        2. Matter and Spirit
        3. Matter and Energy
        4. Temperature, Moisture (Aristotle)
      2. 3 in number
        1. Sattvas, Rajas, Tamas (the Vedas)
        2. Tripartite soul (Plato)
      3. 4 in number
        1. Earth, Air, Fire, Water
      4. or more
        1. Five Elements of TCM
        2. Four Elements plus Spirit – India, elsewhere
    2. Infinite in number
      1. Same or differ only in form – Atomism
      2. Contrary or Different in kind – Mind and Matter, for example.

The Elements and the Categories

First, he looks at the idea that “All is One.” This thesis was defended by many Greek thinkers, both naturalistic and otherwise, and by many other authors ancient and modern. Aristotle attacks them all at once using his doctrine of Categories, which can be found in his book Categories I.4. There is some weird jargon going on here, but it is not merely an exercise in logic-chopping. (The most masterful use of it is in the Nicomachean Ethics I.6, where he uses it to destroy Plato’s ethical theory as well as the possibility of the “Philosopher King”.)

A “category” is a way that one can use the verb “to be”, as in the following:

  • substance- “Lassie is a dog.”
  • quantity- “There are seven days in the week.”
  • quality- “The sky is blue.”
  • relation- “Plato was older that Aristotle. “
  • place- “I am here.”
  • time- “This is now.”
  • position
  • state
  • action
  • affection
  • etc.- and so on and so forth

There could be more categories, the key thing is here is what a “category” is. If you are saying “All is One.”, which category of “is” are you using? I fail to see how we can know if “all is one” or not if we do not know what the “is” means.

Somehow I still think that “All is One” in the sense that “we are all made of the same stuff, but have different forms”. Aristotle seems to think that there are either two or three “elements”, and he prefers two elements “hot/cold” and “dry/wet”, which then combine to form the Four Elements of Fire, Air, Water and Earth.

I and most modern physicists seem to think that there simply has to be one underlying stuff out of which matter, energy, space, time, or whatever all come. But once you read his use of the categories in other contexts, you will have lots of respect for it. In fact, it is one of the things where he really anticipates modern ideas of information useful in software development.


All change is from A to !A. Therefore, “All principles must be contraries.” (???? but substances cannot be contraries, as he says later.)

“(The universal is knowable in the order of explanation, the particular in the order of sense; for explanation has to do with the universals, sense with the particular)” (189a5-10)

Note that “aitia” here is ambivalent (it can mean either (“explanations” or “causes”); universals (according to Aristotle) can be explanations but not causes.


Q: How many physical principles exist?

A: NOT one, because no contrary.

NOT infinite, because unknowable.

Thus a finite munber of principles.
Q: Are yin and yang sufficient for physics?
A: “[I]t should be plausible to suppose then more than two. For it is difficult to see how either density could act on rarity… Love does not gatherStrife together and make things out of it.” (198a23)

Contraries cannot be the substance of the thing. (198a30)

“Substance” is the third thing, such as the monistic Arche of the Physiologoi: Water, Fire, Apeiron, Atoms. The indeterminate prime matter is best since it seems that fire, water et al are already one of the extremes.

Three principles:

  1. The One – Arche, Substance
  2. Excess
  3. Defect

It is common for thinkers to arrange their physical principles into categories of “active” and “passive”:

Active: Love, Strife, Fire, Mind

Passive: Apeiron, Earth, Matter

Book II

Section 1

What is nature?

“Nature” (Grk. phusis) – a principle of change in itself and not in an other.


  • Animals
  • Plants
  • “Simple bodies” –  The Four Elements: Earth, Air, Fire, Water

All of these has in itself its own principle of change or of staying unchanged.

  • Movement, Holding still
  • Growth
  • Decay
  • Alteration

A bed or a coat has no innate principle qua product of skill or art (Grk. tekne). However, the matter from which it is made is still natural, and thus has its own principle of change within it qua natural material. This means that if a wooden bed could grow, it would sprout a tree, not another bed. The natural movement of the bed is to fall if dropped, not to move about, mate with other beds, grow into a full-sized bed. Falling is the natural movement of its matter, not due to its artificial form as bed. Living creatures, on the other hand have natural movement specific to their forms. Snails and octopi are similar in matter, but not in form, and their form determines their natural behavior. But wooden furniture all behaves the same way which depends only on how they are used by others.

The bed is natural as matter, but not as bed (form). The form comes from  the craftsman, not the matter itself.

Both phusis and tekne are principles of change, but phusis is a principle of self-change.

A doctor uses tekne to heal an other, but natural healing is when the body heals itself. On occasion, doctors may treat themselves, but this is still not “natural” (kata phusis – “according to nature).  On the contrary, natural healing can never heal an other. This is even more clearly true of the skills of carpentry, masonry, sculpture, painting, et cetera.

[Another difference between nature and skill is that skill can also be used to create the opposite effect, for example a doctor can use their knowledge to kill or harm. The body’s natural healing powers can never be used to cause harm. See Metaphysics Book VII]

Various conceptions of “nature”.

Phusis as Matter (193.10)

Some believe that the nature of a thing is its matter, since the matter was there prior to form. For composite materials (“compounds”), the nature of the compound is derived from the nature of the simple elements that form the compound.

Some materialists have chosen one of the simple elements for the role of fundamental element. (E.g. Thales “All is Water.”)

Phusis as Form  (193.30)

Another way of defining nature is “the form which accords with its logos.”

“Men (anthropoi) come from men.” – Natural beings contain their own forms.
“Beds do not come from beds.” – Artificial beings do not contain their own form.

On this view of Phusis as Form natural beings can only be by having a form. On this view, matter without a form is not really a being (“ontos on“, Greek for “really real”). Matter comes to be a being by taking form, either by necessity, nature, or art.  (See Plato’s “Phaedo” and Aristotle’s “On Generation and Corruption” II.9)

Phusis as Telos (193.15)

Art does not produce art. Medicine produces health, not medicine.

Nature produces nature. Humans produce humans.

Is this true? -“The telos of nature is to produce the form, and the telos of the form is to manifest proper activity.” (This is just me talking, not Aristotle.)

On this view the nature of thing is its function, purpose or final cause. This is like saying that the “nature” of wings is to fly, the nature of humans is politics.

Section 2 – Nature and Mathematics

How natural or unnatural is mathematics?

Geometrical volumes are separate from physical matter.

  • “Geometry treats of natural lines, but not as natural. Optics treats of mathematical lines but as natural.”
  • “Two sort of things are called “nature”, form and matter.”
    • The physiologoi focused on matter.
    • But art treats of both matter and form, so maybe science should as well.
      • The doctor knows:
        • The Form/Telos of Health
        • The matter of the body.
      • The builder knows:
        • The form of the building.
        • The purpose of the building.
        • The matter for building.

List of senses of “form”

See also here for a more detailed treatment.

  • Genus/species
  • Quantity
    • Geometry
    • Arithmetic
  • Logical
    • Definition
      • Metadata
      • Data
    • Algorithm
  • “Mere” Recognition of Eidos
  • Biological Form
    • DNA
    • Other biological information
      • RNA
      • mDNA
      • other protein signatures
  • Technical Form
    • Know How
    • Design/Plan

Notes concerning this section from Aristotle, by Sir David Ross (pg. 68 ff)

  • Aristotle defines the nature of physics by
    • Comparing it with math
      • The mathematician studies nature as form only.
        • Terrestrial matter
        • Celestial matter
        • Intelligible matter
        • In any case, they ignore the matter and only treat the form.
      • The physicist studies nature as:
        • form and matter – doctors and builders
          • Primarily form
          • Matter as it relates to form
        • Agent and telos
        • The study of physics and tekkie both study all four causes.
    • Asking how it approaches nature.
      • As form?
      • As matter?
      • as both? (Yes to this one: pg. 70)
    • Questions
      • Why does a certain form require a certain matter?
      • Conversely, why does certain matter only take certain forms?
  • Aristotle compares Physics and Metaphysics as well:
    • Physics studies
      • Forms abstracted from nature
      • Ends serves by natural beings.
    • Metaphysics studies separately existing forms/ends
      • God
      • gods
      • Human intellects()?

Section 3 – The Four Causes

Material Causes

  • Bronze -> Statue
  • Silver -> Cup

Formal causes

  • “Account of what a thing might be”
  • “And its genera”
  • Octave = “ratio of 2:1” as well as other numerical relations/dimensions.

Efficient Causes

  • “Primary source of the change or of staying unchanged.”
    • One who has deliberated -> deliberate action
    • parent->child

Telos – “Final causes”

  • walking ->”health”/”keeping fit”
  • health is the telos of:
    • the quality of slimness
    • the action of purging
    • the use of drugs (as tools ?)

Section 4 – Chance and Automaton.

Yes, because…

Section 5 – What is luck (tyche)?

Loosely speaking, “luck” is a “cause”, but in reality they are very different from other causes. To explain why, we will review the others sorts of (more real) causes.

  • Nature
    • comes to be always or most of the time
    • Luck does not; it happens rarely
    • “Of the things that come to be, some come to be for something, some not. Of the former, some are in accordance with choice; some not, but both are among things which are for something.”

Ch. 6 – Luck and automaton.

Of things that are neither by nature nor by choice:

  • If it is for something, it is “luck”.
  • If not, it is automaton (Greek, “spontanaeity”, also translated as “automatic”.).

Luck is for something by concurrence, not by choice.

“But since automaton and luck are causes of things for which mind or nature might be responsible, when something comes to be responsible for these things by virtue of concurrence, and since nothing which by virtue of concurrence is prior to that which is by itself, it is clear that no cause by virtue of concurrence is prior to that which is by itself a cause. Hence the automatic and luck are posterior to both mind and nature…”(“Physics” 198 5-10)

Ch.7- What are causes?

What are causes? = “On account of what?”

There are four causes:

  1. Form – “What is it?”
  2. Efficient – “What first effects the change?”
  3. Final – “What is it for?”
  4. Matter- “What is it made of?”

1-3 “often coincide”.

  • Form is often the final cause.
    • The form of many products of skill is “whatever works“.
  • For natural beings:
    • The telos of growth is the mature form.
    • The Form is also the efficient cause, since the mature form is that which generates offspring.

Ch.8 – Telos: Natural and Artificial.

Ch.9 – Nature and Necessity

Book IV


Q: What is the essence of “place”?

A: Anything we say of place is either: 1) IN virtue of itself OR 2) In virtue of another.

“there is place which is common and in which all bodies are AND which is the proper and primary location of each body.”

Place is either 1) Form – as the container of each body or 2) Matter – as the extension of each body. [Or telos – the proper place of each body.]

“In so far as it is separable from the thing, it is not the form; and in so far as it is different from matter, it is not the matter.”

Book VII

Ch. 6 – The Prime Mover

Primary and ultimate source of change in nature

  • Eternal – because natural change is eternal, therefore there must be an eternal source of change.
  • Unmoved -Only an unmoved mover would be a constant source of change
  • Good – Only a final cause is unmoved.
  • Omniscient(?) – sort of, but only of the first principles of natural change
  • Omnibenevolent(?) – kind of, in the sense that it is “the Good”

Other treatments concerning nature and tekne in Aristotle.

Metaphysics V: Definitions of

Section 1: arkhe – “principle”, “beginning”, “leader”

Section 2:  aitia – “causes”, “exlanations”

Section 3: stoicheia – “elements”

Section 4: phusis – “nature”

Metaphysics VII, 7-9: Natural and artificial “powers” or abilites.

On the Soul I.1ff – Focuses on living natural beings.

Nicomachean Ethics I.1ff – “What is the telos of human life?” Focuses on natural living human beings.

If you like this post check out my podcast “The Aristotle Project“.


One thought on “Notes on Aristotle’s “Physics”

  1. Pingback: Notes on Aristotle’s “Metaphysics” Book VII | Zoon Echon Blogon

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