Phi2391A: Rise and Fall of Aristotelian Science 0 Aristotle

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Rise and Fall of Aristotelian Science



  • Science & Philosophy of Science begin with Aristotle

  • Who was Aristotle?

  • 384-322 BC Born: Stagira (The Stagirite)

  • Student of Plato

  • Founder of the Lyceum/Peripatetic school

Who was Aristotle?

  • First “systematic” thinker in the philosophical tradition

  • Prior to Socrates/Plato (pre-socratics):

  • Various schools of learning

  • Parmenides, Zeno, Thales, Heraclitus

  • Propose new ways of thinking

  • Explanations of the origins of the universe

  • Nature of matter

  • Nature of change

Who was Aristotle?

  • Ways of describing world that are opposed to

  • Myth/Religion

  • Philosophy at its origin irreligious

  • Early consequence: Socrates put to death by Athenians

  • We would say: seeks “natural” explanations

Who was Aristotle?

  • Socrates, his student Plato, initiate school of philosophy - The Academy

  • Central doctrines:

  • Theory of Forms

  • Theory of Recollection


  • All beings have (participate in) “forms”

  • Not spatio-temporal/material, but unchanging

  • Material world consists of copies of the forms

  • Knowledge consists in grasping formal character of things

  • Material objects not real

  • Learning a kind of “remembering” (mathematics)

Who was Aristotle?

  • Aristotle rejects Plato’s doctrine of forms (“School of Athens”)

  • Importance for us: theory of change

The problem of change

  • Zeno’s paradox

  • “Eleatic” (Elea) paradox of being and change

  • In change a thing (a being) becomes something different

  • Since it is not what it becomes, in change a being (what-is) becomes a non-being (what-is-not)

  • Conclusion: there is no change/becoming

  • Being simply is

The problem of change

  • Platonic “solution”: what is is a form

  • Material objects are copies/shadows of forms

  • As non-beings, they can change, but forms - beings - never change

  • Material objects are not, they merely appear

  • They are seemings, “phainomena”

Aristotle on change and forms

  • Aristotle rejects Plato’s “other world” theory

  • Beings have forms, but these beings are in this world:

  • Animals, rocks, trees, humans are all be-ings So how can they change?

Form & matter

  • The beings of this world are not just forms

  • They are “informed matter”

  • Matter (Gr. hylé - wood, Lat. materia) is not what we think of as matter

  • Matter is that aspect of a thing which is not its primary being

  • Each thing has a primary being that makes it “what it is” (later: Lat.“essentia” from “essere” to be”)

Form & matter

  • So a horse has the form/essence of “horseness” (Plato would have said this)

  • But it also has aspects of its being that are not primary. For instance qualities or properties

  • Colour, height, weight, softness, hardness

  • The “total horse” is a composite of its form (horseness) and the material properties

How does this relate to the problem of change?

  • Aristotle: Two fundamental species of change

  • (1) Change of properties

  • (2) Coming-to-be [“generation”] and passing-away [“destruction”]

  • In (1), the essence/being of a thing remains the same (it “be’s” what it is)

  • But the matter changes (it grows or shrinks, changes colour, etc.)

How does this relate to the problem of change?

  • In (2) the being/essence of a thing changes

  • But then Parmenides and Zeno kick in:

  • If the being changes, the thing is not (is no longer) so the change is not a change

  • It is a destruction

  • Similarly, what is after the change is new

  • It is a “coming-to-be” or a generation

  • We will return to (1) - qualitative change - below

Form, matter and change

  • The form/matter composite thus a theory fundamentally addressed to problem of change

  • Theories of this sort - theories that say what the fundamental character of being is are called

  • Metaphysical theories

  • Word does not exist for Aristotle:

  • “First philosophy” (Physics 194b14)

Form/matter and generality

  • There is a connection between being and language

  • Culminates in mature Aristotelian view (cf. Losee, p. 12-13)

  • What we call a “correspondence theory of truth”

  • But is there in Plato’s theory of forms

Forms and language

  • A form makes a thing what it is

  • Plato’s forms are unique

  • Each appears multiply in the spatio-temporal world

  • There are many horses, each of which is a horse (Compare: Hydrogen atoms)

  • For Plato, each individual horse is a copy of the ideal form of the horse

Forms and language

  • The theory explains why we - correctly - use one word to refer to this class of individuals

  • They are all instances of the same form

  • And when we correctly call something a horse

  • We say of that individual that it partakes in/manifests that form

Forms and laws

  • Use of formal language allows the formation of general laws

  • “Horses nurture their young”

  • “Pie-O-My is a horse”

  • “Pie-O-My will nurture its young”

  • It permits us to formulate generally true propositions

  • Propositions about kinds of things

Matter and individuality

  • In Plato’s theory, the horses are copies of the ideal horse

  • Knowledge (philosophy/science) is knowledge of forms

  • It is expressed in general term in language

  • In this sense, language is always about the general case

  • We do not have knowledge of specific cases

Matter and individuality

  • In Aristotle’s theory, there are no ideal forms

  • There is just the group of horses, which are form/matter composites

  • The matter individuates the horses

  • Each has different properties

  • Each is in a different place, has a different shape, size and colour

  • Remember: “matter” means all kinds of properties

Knowledge in Aristotle

  • But just as in Plato, knowledge is always of forms

  • Even properties, like redness, are considered formally when we do science

  • We never talk about this red patch

  • But about red patches

  • For Aristotle, everything, even properties, have being, or form

  • But properties only have being and form in a secondary sense

Change in Aristotle

  • We said: aside from creation and destruction, change for Aristotle is qualitative

  • Whenever a thing changes, its primary form remains the same, and the matter changes

  • The primary form is the being, essence, nature of the thing (horseness)

  • The matter is the set of properties that individuates it

Change in Aristotle

  • The various kinds of properties, Aristotle calls categories

  • Include qualities like colour, heaviness

  • Locations like above/below

  • (Being is also a special category)

  • So a thing has a categorical structure

  • And change is change of that structure

  • For each category, there is a corresponding kinds of change (Physics 201a1-9)

Change in Aristotle

  • Change is characterised by a transition from potentiality to actuality

  • “the actuality of that which potentially is is … is change”

  • When the matter of a tree’s leaves change from green to red, what is potentially red becomes actually red.

Change in Aristotle

  • Matter, as the ground of change, is potentiality

  • When it takes on a form, it is actualised

  • Motions begin in potentiality and end in actuality

Change in Aristotle

  • The study of change is the study of nature

  • Greek physis, thus physics

  • Aristotle: nature “a cause and source of change” (192a21)

  • Physics is thus the science that understands the causes and sources of change


  • Remember the origins of form/matter theory in Eleatic paradoxes

  • Would expect a connection to the theory of motion

  • Indeed, form and matter appear as “causes” of motion

  • Two other causes in addition (Phys 195a20-27) :

  • End (“final”, Lat. finis - end)

  • Maker (“efficient”, Lat. facere - to make, p.p. factum)

Change and causes

  • Let’s put together theory of change and theory of causes

  • Change is a change within categories

  • The properties of a being/form change, this is a material change

  • The causes of the change are thus causes of the alteration of properties

  • While the thing remains the same (unless destroyed)

Change and causes

  • Question: Why does a change take place?

  • Because of the matter: theory of elements

  • Because of the form

  • “…nature is the shape and form of things which have in them the source of their changes” (Phys 193b1-5)

Nature and techné (art)

  • Note that “source of their changes” suggests what Aristotle calls a cause

  • So the nature is the form of a thing that has its causes “in it”

  • Aristotle distinguishes between things “by art” and “by nature”

  • In both sort of thing, the matter is there “for the sake of” the form

Nature and techné (art)

  • So the wood (remember “matter” is the same word as “wood” in Aristotle) of the bed is for the sake of sleeping on it

  • The bed has a form, but the form was given to it by the man who made it

  • Thus matter and form are un-naturally combined

  • If you plant a bed, it sprouts a tree, not a bed

Nature and techné (art)

  • Aristotle’s definition of natural forms is deeply influenced by understanding of technical forms

  • E.g. Phys 194a35f. comparison of artificial and natural objects

  • “In the case, then, of artefacts we make the matter for the work to be done, whilst in the case of natural objects it is there already.”

Nature and techné (art)

  • Note preceding distinction: the nature of a rudder

  • There is the knowledge of what it is for (the steersman)

  • There is the question of how it is to be made

  • When both are combined, we get a form/matter composite where

  • The matter is in a form, for the sake of an end

Causal structure

  • So the causal structure of the rudder is:

  • Material cause: wood

  • Formal cause: shape

  • Efficient cause: carpenter

  • Final cause: steering

  • Aristotle: in natural objects, “the last three often coincide” 198a24

Natural entities and change

  • So the science of nature is the science of things whose form and matter are for the sake of an end

  • Primary example: animals, plants

  • Entities with organic structure

  • Aristotle calls the form/nature of living things a “psyché” (soul - principle of life)

  • But theory not restricted to living things

Natural entities and change

  • Aristotle explains motion of “inanimate” objects finally as well

  • Rocks fall because they “tend” downwards

  • It is in their “nature” to move downward (change in the category of position)

  • (But not all change is “natural” in this sense)

Natural entities and change

  • In an organic being, the matter is organised for the form

  • And the formal and final causes coincide: organisms exists for the sake of continuing to be what they are

  • And to reproduce (the end of creating a new form)

  • Grounds key notion: “essential properties”

Essential properties

  • Different kinds of animals have different forms, ways of life

  • In each case, the form and matter of the animal adapted to way of life

  • Ultimate final causes: nutrition, locomotion, perception, intellection

  • We have teeth “in order to” eat

  • We have eyes “in order to” see

Essential properties and natural motions

  • Certain aspects of a thing are essential

  • “For its being”

  • Those organisational and material properties which make it the kind of thing it is

  • And motions that occur for these essential ends are “natural”

  • Holds even for rock

Essential properties and natural motions

  • Natural motion of rock: falling downwards

  • Forced motion: rock thrown at bird by hunter

  • The motion is for the sake of something external to the nature of the rock

  • Rock will fall to ground once the forced motion “wears off”

Essential properties and natural motions

  • Aristotle’s theory of physics restricted

  • Only a small subset of what happens qualifies as natural motion

  • “Why should not everything be like the rain?” (199a17)

  • Aristotle speaks of “necessary”, “automatic”, “coincidental” motions

  • These are things that “just happen”

  • For no reason (with no cause)

Essential properties and natural motions

  • Among these are motions due to impact, displacement, etc.

  • “Forced motions” (the thrown rock)

  • In general, motions not directed towards an essential (natural) end

The Platonic Remnant

  • Aristotle’s conception of science retains Platonic elements

  • Knowledge (philosophy/science) is knowledge of forms

  • So scientific knowledge - unavoidably - becomes knowledge of essential properties of things

  • Particularly: knowledge of natural forms which govern - finally - natural motions

  • Where these are conceived teleologically (Gr. telos - end, goal)

Problems for Aristotle

  • Modern perspective: Aristotle “unscientific”. Why?

  • No mathematics

  • Final causes

  • Large mass of “random” events

  • How would Aristotle defend himself against these charges?

The status of mathematics

  • Mathematician is not a natural scientist

  • But: natural science can use mathematics (Astronomy, Phys 193b26)

  • Why is he not a natural scientist?

  • What is mathematics about?

The status of mathematics

  • Mathematics concerned with forms, but not with essential forms

  • Mathematical forms are shapes

  • These fall under the categories of size, position, direction

  • So they are “accidental” (non-essential) or, simply, “material” aspects of things

  • But they are considered “separately” of any specific thing

The status of mathematics

  • Mathematics studies formal characteristics of matter

  • Not all such characteristics

  • Those that are spatial

  • Formally, because without regard to specifics

  • But material, because not concerned with essential properties of individuals

The status of mathematics

  • But - obviously - most material properties, e.g. colours, are not mathematical

  • And, “Odd and even, straight and curved … can be defined without change but flesh, bone and man cannot.” (Phys 194a4)

  • I.e. they are not about change

Final causes and random events

  • Paul Feyerabend: Think of Aristotle’s universe as one which is “pulled forwards”

  • Events are the material changes of primary substances (form/matter composites)

  • Among the events, there are some that happen “for” the form of substances (independent form/matter composites)

  • So natural motions are forward directed

Final causes and random events

  • Recall: motions begin in potentiality and end in actuality

  • The universe consists of a sequence of transitions from potential to actual states

  • But this sequence is disrupted

Final causes and random events

  • Automatic, coincidental events coexist with the natural motions

  • May interfere with them

  • Automatic motions - the tripod collapsing (197b17) - happen on a purely material level

  • But such purely material events are scientifically ungraspable

Random events

  • Recall: Science is about general forms and laws

  • Laws reflect the action of essential forms on matter

  • They are general because they are formal

  • Matter is the ground of potentiality and change

  • Automatic events happen spontaneously, i.e. there is no reason why they should happen

  • In this sense, there can be no science of matter for Aristotle

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