Aristotelian physics is a form of natural science described in the
works of the Greek philosopher
Aristotle (384–322 BCE). In his
Aristotle intended to establish general principles of
change that govern all natural bodies, both living and inanimate,
celestial and terrestrial – including all motion, change with
respect to place, change with respect to size or number, qualitative
change of any kind; and "coming to be" (coming into existence,
"generation") and "passing away" (no longer existing, "corruption").
To Aristotle, "physics" was a broad field that included subjects such
as the philosophy of mind, sensory experience, memory, anatomy and
biology. It constitutes the foundation of the thought underlying many
of his works.
2.1 Elements and spheres
2.1.1 Celestial spheres
2.2 Terrestrial change
2.3 Natural place
2.4 Natural motion
2.5 Unnatural motion
2.6 Continuum and vacuum
2.7 Four causes
2.8.1 Organism and mechanism
3 Medieval commentary
4 Life and death of Aristotelian physics
5 As listed in the Corpus Aristotelicum
6 See also
10 Further reading
A page from an 1837 edition of the ancient Greek philosopher
Aristotle's Physica, a book addressing a variety of subjects including
the philosophy of nature and topics now part of its modern-day
nature is everywhere the cause of order.
While consistent with common human experience, Aristotle's principles
were not based on controlled, quantitative experiments, so, while they
account for many broad features of nature, they do not describe our
universe in the precise, quantitative way now expected of science.
Aristotle like Aristarchus rejected these principles
in favor of heliocentrism, but their ideas were not widely accepted.
Aristotle's principles were difficult to disprove merely through
casual everyday observation, but later development of the scientific
method challenged his views with experiments and careful measurement,
using increasingly advanced technology such as the telescope and
In claiming novelty for their doctrines, those natural philosophers
who developed the “new science” of the seventeenth century
frequently contrasted “Aristotelian” physics with their own.
Physics of the former sort, so they claimed, emphasized the
qualitative at the expense of the quantitative, neglected mathematics
and its proper role in physics (particularly in the analysis of local
motion), and relied on such suspect explanatory principles as final
causes and “occult” essences. Yet in his
characterizes physics or the “science of nature” as pertaining to
magnitudes (megethê), motion (or “process” or “gradual
change” – kinêsis), and time (chronon) (Phys III.4 202b30–1).
Physics is largely concerned with an analysis of motion,
particularly local motion, and the other concepts that Aristotle
believes are requisite to that analysis.
— Michael J. White, "
Aristotle on the Infinite, Space, and Time"
in Blackwell Companion to Aristotle
Peter Apian's 1524 representation of the universe, heavily influenced
by Aristotle's ideas. The terrestrial spheres of water and earth
(shown in the form of continents and oceans) are at the center of the
universe, immediately surrounded by the spheres of air, and then fire,
where meteorites and comets were believed to originate. The
surrounding celestial spheres from inner to outer are those of the
Moon, Mercury, Venus, Sun, Mars, Jupiter, and Saturn, each indicated
by a planet symbol. The eighth sphere is the firmament of fixed stars,
which include the visible constellations. The precession of the
equinoxes caused a gap between the visible and notional divisions of
the zodiac, so medieval Christian astronomers created a ninth sphere,
the Crystallinum which holds an unchanging version of the
zodiac. The tenth sphere is that of the divine prime mover
Aristotle (though each sphere would have an unmoved
mover). Above that, Christian theology placed the "Empire of God".
What this diagram does not show is how
Aristotle explained the
complicated curves that the planets make in the sky. To preserve the
principle of perfect circular motion, he proposed that each planet was
moved by several nested spheres, with the poles of each connected to
the next outermost, but with axes of rotation offset from each other.
Aristotle left the number of spheres open to empirical
determination, he proposed adding to the many-sphere models of
previous astronomers, resulting in a total of 44 or 55 celestial
Elements and spheres
Main article: Classical element
Aristotle divided his universe into "terrestrial spheres" which were
"corruptible" and where humans lived, and moving but otherwise
unchanging celestial spheres.
Aristotle believed that four classical elements make up everything in
the terrestrial spheres: earth, air, fire and water.[a] He also
held that the heavens are made of a special weightless and
incorruptible (i.e. unchangeable) fifth element called "aether".
Aether also has the name "quintessence", meaning, literally, "fifth
Aristotle considered heavy substances such as iron and other metals to
consist primarily of the element earth, with a smaller amount of the
other three terrestrial elements. Other, lighter objects, he believed,
have less earth, relative to the other three elements in their
The four classical elements were not invented by Aristotle; they were
originated by Empedocles. During the Scientific Revolution, the
ancient theory of classical elements was found to be incorrect, and
was replaced by the empirically tested concept of chemical elements.
Aether (classical element)
Aether (classical element) and Dynamics of the
According to Aristotle, the Sun, Moon, planets and stars – are
embedded in perfectly concentric "crystal spheres" that rotate
eternally at fixed rates. Because the celestial spheres are incapable
of any change except rotation, the terrestrial sphere of fire must
account for the heat, starlight and occasional meteorites. The
lowest, lunar sphere is the only celestial sphere that actually comes
in contact with the sublunary orb's changeable, terrestrial matter,
dragging the rarefied fire and air along underneath as it rotates.
Like Homer's æthere (αἰθήρ) – the "pure air" of Mount
Olympus – was the divine counterpart of the air breathed by
mortal beings (άήρ, aer). The celestial spheres are composed of the
special element aether, eternal and unchanging, the sole capability of
which is a uniform circular motion at a given rate (relative to the
diurnal motion of the outermost sphere of fixed stars).
The concentric, aetherial, cheek-by-jowl "crystal spheres" that carry
the Sun, Moon and stars move eternally with unchanging circular
motion. Spheres are embedded within spheres to account for the
"wandering stars" (i.e. the planets, which, in comparison with the
Sun, Moon and stars, appear to move erratically). Mercury, Venus,
Mars, Jupiter, and Saturn are the only planets (including minor
planets) which were visible before the invention of the telescope,
which is why Neptune and Uranus are not included, nor are any
asteroids. Later, the belief that all spheres are concentric was
forsaken in favor of Ptolemy's deferent and epicycle model. Aristotle
submits to the calculations of astronomers regarding the total number
of spheres and various accounts give a number in the neighborhood of
fifty spheres. An unmoved mover is assumed for each sphere, including
a "prime mover" for the sphere of fixed stars. The unmoved movers do
not push the spheres (nor could they, being immaterial and
dimensionless) but are the final cause of the spheres' motion, i.e.
they explain it in a way that's similar to the explanation "the soul
is moved by beauty".
The four terrestrial elements
Unlike the eternal and unchanging celestial aether, each of the four
terrestrial elements are capable of changing into either of the two
elements they share a property with: e.g. the cold and wet (water) can
transform into the hot and wet (air) or the cold and dry (earth) and
any apparent change into the hot and dry (fire) is actually a two-step
process. These properties are predicated of an actual substance
relative to the work it is able to do; that of heating or chilling and
of desiccating or moistening. The four elements exist only with regard
to this capacity and relative to some potential work. The celestial
element is eternal and unchanging, so only the four terrestrial
elements account for "coming to be" and "passing away" – or, in
the terms of Aristotle's De Generatione et Corruptione (Περὶ
γενέσεως καὶ φθορᾶς), "generation" and
The Aristotelian explanation of gravity is that all bodies move toward
their natural place. For the elements earth and water, that place is
the center of the (geocentric) universe; the natural place of
water is a concentric shell around the earth because earth is heavier;
it sinks in water. The natural place of air is likewise a concentric
shell surrounding that of water; bubbles rise in water. Finally, the
natural place of fire is higher than that of air but below the
innermost celestial sphere (carrying the Moon).
In Book Delta of his
Aristotle defines topos (place)
in terms of two bodies, one of which contains the other: a "place" is
where the inner surface of the former (the containing body) touches
the outer surface of the other (the contained body). This definition
remained dominant until the beginning of the 17th century, even though
it had been questioned and debated by philosophers since
antiquity. The most significant early critique was made in terms
of geometry by the 11th-century Arab polymath al-Hasan Ibn al-Haytham
(Alhazen) in his Discourse on Place.
Terrestrial objects rise or fall, to a greater or lesser extent,
according to the ratio of the four elements of which they are
composed. For example, earth, the heaviest element, and water, fall
toward the center of the cosmos; hence the
Earth and for the most part
its oceans, will have already come to rest there. At the opposite
extreme, the lightest elements, air and especially fire, rise up and
away from the center.
The elements are not proper substances in Aristotelian theory (or the
modern sense of the word). Instead, they are abstractions used to
explain the varying natures and behaviors of actual materials in terms
of ratios between them.
Motion and change are closely related in Aristotelian physics. Motion,
according to Aristotle, involved a change from potentiality to
actuality. He gave example of four types of change.
Aristotle's laws of motion. In
Physics he states that objects fall at
a speed proportional to their weight and inversely proportional to the
density of the fluid they are immersed in. This is a correct
approximation for objects in Earth's gravitational field moving in air
Aristotle proposed that the speed at which two identically shaped
objects sink or fall is directly proportional to their weights and
inversely proportional to the density of the medium through which they
move. While describing their terminal velocity,
stipulate that there would be no limit at which to compare the speed
of atoms falling through a vacuum, (they could move indefinitely fast
because there would be no particular place for them to come to rest in
the void). Now however it is understood that at any time prior to
achieving terminal velocity in a relatively resistance-free medium
like air, two such objects are expected to have nearly identical
speeds because both are experiencing a force of gravity proportional
to their masses and have thus been accelerating at nearly the same
rate. This became especially apparent from the eighteenth century when
partial vacuum experiments began to be made, but some two hundred
Galileo had already demonstrated that objects of
different weights reach the ground in similar times.
Apart from the natural tendency of terrestrial exhalations to rise and
objects to fall, unnatural or forced motion from side to side results
from the turbulent collision and sliding of the objects as well as
transmutation between the elements (On Generation and Corruption).
Aristotle examines accidents (συμβεβηκός,
symbebekòs) that have no cause but chance. "Nor is there any definite
cause for an accident, but only chance (τύχη, týche), namely an
indefinite (ἀόριστον, "aóriston") cause" (Metaphysics V,
It is obvious that there are principles and causes which are generable
and destructible apart from the actual processes of generation and
destruction; for if this is not true, everything will be of necessity:
that is, if there must necessarily be some cause, other than
accidental, of that which is generated and destroyed. Will this be, or
not? Yes, if this happens; otherwise not (Metaphysics VI, 1027a29).
Continuum and vacuum
Aristotle argues against the indivisibles of
Democritus (which differ
considerably from the historical and the modern use of the term
"atom"). As a place without anything existing at or within it,
Aristotle argued against the possibility of a vacuum or void. Because
he believed that the speed of an object's motion is proportional to
the force being applied (or, in the case of natural motion, the
object's weight) and inversely proportional to the viscosity of the
medium, he reasoned that objects moving in a void would move
indefinitely fast – and thus any and all objects surrounding
the void would immediately fill it. The void, therefore, could never
The "voids" of modern-day astronomy (such as the
Local Void adjacent
to our own galaxy) have the opposite effect: ultimately, bodies
off-center are ejected from the void due to the gravity of the
Four causes and Teleology
According to Aristotle, there are four ways to explain the aitia or
causes of change. He writes that "we do not have knowledge of a thing
until we have grasped its why, that is to say, its cause."
Aristotle held that there were four kinds of causes.
The material cause of a thing is that of which it is made. For a
table, that might be wood; for a statue, that might be bronze or
“In one way we say that the aition is that out of which. as
existing, something comes to be, like the bronze for the statue, the
silver for the phial, and their genera” (194b2 3—6). By
Aristotle means more general ways of classifying the
matter (e.g. “metal”; “material”); and that will become
important. A little later on. he broadens the range of the material
cause to include letters (of syllables), fire and the other elements
(of physical bodies), parts (of wholes), and even premisses (of
Aristotle re-iterates this claim, in slightly different
terms, in An. Post II. 11).
— R.J. Hankinson, "The Theory of the Physics" in Blackwell
Companion to Aristotle
The formal cause of a thing is the essential property that makes it
the kind of thing it is. In Metaphysics Book Α
that form is closely related to essence and definition. He says for
example that the ratio 2:1, and number in general, is the cause of the
"Another [cause] is the form and the exemplar: this is the formula
(logos) of the essence (to ti en einai), and its genera, for instance
the ratio 2:1 of the octave” (Phys 11.3 194b26—8)... Form is not
just shape... We are asking (and this is the connection with essence,
particularly in its canonical Aristotelian formulation) what it is to
be some thing. And it is a feature of musical harmonics (first noted
and wondered at by the Pythagoreans) that intervals of this type do
indeed exhibit this ratio in some form in the instruments used to
create them (the length of pipes, of strings, etc.). In some sense,
the ratio explains what all the intervals have in common, why they
turn out the same.
— R.J. Hankinson, "Cause" in Blackwell Companion to Aristotle
The efficient cause of a thing is the primary agency by which its
matter took its form. For example, the efficient cause of a baby is a
parent of the same species and that of a table is a carpenter, who
knows the form of the table. In his
Physics II, 194b29—32, Aristotle
writes: "there is that which is the primary originator of the change
and of its cessation, such as the deliberator who is responsible [sc.
for the action] and the father of the child, and in general the
producer of the thing produced and the changer of the thing changed".
Aristotle’s examples here are instructive: one case of mental and
one of physical causation, followed by a perfectly general
characterization. But they conceal (or at any rate fail to make
patent) a crucial feature of Aristotle’s concept of efficient
causation, and one which serves to distinguish it from most modern
homonyms. For Aristotle, any process requires a constantly operative
efficient cause as long as it continues. This commitment appears most
starkly to modern eyes in Aristotle’s discussion of projectile
motion: what keeps the projectile moving after it leaves the hand?
“Impetus,” “momentum,” much less “inertia,” are not
possible answers. There must be a mover, distinct (at least in some
sense) from the thing moved, which is exercising its motive capacity
at every moment of the projectile’s flight (see Phys VIII. 10
266b29—267a11). Similarly, in every case of animal generation, there
is always some thing responsible for the continuity of that
generation, although it may do so by way of some intervening
instrument (Phys II.3 194b35—195a3).
— R.J. Hankinson, "Causes" in Blackwell Companion to Aristotle
The final cause is that for the sake of which something takes place,
its aim or teleological purpose: for a germinating seed, it is the
adult plant, for a ball at the top of a ramp, it is coming to rest
at the bottom, for an eye, it is seeing, for a knife, it is cutting.
Goals have an explanatory function: that is a commonplace, at least in
the context of action-ascriptions. Less of a commonplace is the view
espoused by Aristotle, that finality and purpose are to be found
throughout nature, which is for him the realm of those things which
contain within themselves principles of movement and rest (i.e.
efficient causes); thus it makes sense to attribute purposes not only
to natural things themselves, but also to their parts: the parts of a
natural whole exist for the sake of the whole. As
notes, “for the sake of” locutions are ambiguous: "A is for the
sake of B" may mean that A exists or is undertaken in order to bring B
about; or it may mean that A is for B’s benefit (An II.4 415b2—3,
20—1); but both types of finality have, he thinks, a crucial role to
play in natural, as well as deliberative, contexts. Thus a man may
exercise for the sake of his health: and so “health,” and not just
the hope of achieving it, is the cause of his action (this distinction
is not trivial). But the eyelids are for the sake of the eye (to
protect it: PA II.1 3) and the eye for the sake of the animal as a
whole (to help it function properly: cf. An II.7).
— R.J. Hankinson, "Causes" in Blackwell Companion to Aristotle
Main article: Aristotle's biology
According to Aristotle, the science of living things proceeds by
gathering observations about each natural kind of animal, organizing
them into genera and species (the differentiae in History of Animals)
and then going on to study the causes (in
Parts of Animals
Parts of Animals and
Generation of Animals, his three main biological works).
The four causes of animal generation can be summarized as follows. The
mother and father represent the material and efficient causes,
respectively. The mother provides the matter out of which the embryo
is formed, while the father provides the agency that informs that
material and triggers its development. The formal cause is the
definition of the animal’s substantial being (GA I.1 715a4: ho logos
tês ousias). The final cause is the adult form, which is the end for
the sake of which development takes place.
— Devin M. Henry, "Generation of Animals" in Blackwell Companion
Organism and mechanism
Organism (philosophy) and Mechanism (philosophy)
The four elements make up the uniform materials such as blood, flesh
and bone, which are themselves the matter out of which are created the
non-uniform organs of the body (e.g. the heart, liver and hands)
"which in turn, as parts, are matter for the functioning body as a
whole (PA II. 1 646a 13—24)".
[There] is a certain obvious conceptual economy about the view that in
natural processes naturally constituted things simply seek to realize
in full actuality the potentials contained within them (indeed, this
is what is for them to be natural); on the other hand, as the
Aristotelianism from the seventeenth century on were not
slow to point out, this economy is won at the expense of any serious
empirical content. Mechanism, at least as practiced by Aristotle’s
contemporaries and predecessors, may have been explanatorily
inadequate — but at least it was an attempt at a general account
given in reductive terms of the lawlike connections between things.
Simply introducing what later reductionists were to scoff at as
“occult qualities” does not explain — it merely, in the manner
of Molière’s famous satirical joke, serves to re-describe the
effect. Formal talk, or so it is said, is vacuous.
Things are not however quite as bleak as this. For one thing,
there’s no point in trying to engage in reductionist science if you
don’t have the wherewithal, empirical and conceptual, to do so
successfully: science shouldn't be simply unsubstantiated speculative
metaphysics. But more than that, there is a point to describing the
world in such teleologically loaded terms: it makes sense of things in
a way that atomist speculations do not. And further, Aristotle’s
talk of species-forms is not as empty as his opponents would
insinuate. He doesn't simply say that things do what they do because
that's the sort of thing they do: the whole point of his
classificatory biology, most clearly exemplified in PA, is to show
what sorts of function go with what, which presuppose which and which
are subservient to which. And in this sense, formal or functional
biology is susceptible of a type of reductionism. We start, he tells
us, with the basic animal kinds which we all pre-theoretically
(although not indefeasibly) recognize (cf. PA I.4): but we then go on
to show how their parts relate to one another: why it is, for
instance, that only blooded creatures have lungs, and how certain
structures in one species are analogous or homologous to those in
another (such as scales in fish, feathers in birds, hair in mammals).
And the answers, for Aristotle, are to be found in the economy of
functions, and how they all contribute to the overall well-being (the
final cause in this sense) of the animal.
— R.J. Hankinson, "The Relations between the Causes" in Blackwell
Companion to Aristotle
See also Organic form.
According to Aristotle, perception and thought are similar, though not
exactly alike in that perception is concerned only with the external
objects that are acting on our sense organs at any given time, whereas
we can think about anything we choose. Thought is about universal
forms, in so far as they've been successfully understood, based on our
memory of having encountered instances of those forms directly.
Aristotle’s theory of cognition rests on two central pillars: his
account of perception and his account of thought. Together, they make
up a significant portion of his psychological writings, and his
discussion of other mental states depends critically on them. These
two activities, moreover, are conceived of in an analogous manner, at
least with regard to their most basic forms. Each activity is
triggered by its object – each, that is, is about the very thing
that brings it about. This simple causal account explains the
reliability of cognition: perception and thought are, in effect,
transducers, bringing information about the world into our cognitive
systems, because, at least in their most basic forms, they are
infallibly about the causes that bring them about (An III.4
429a13–18). Other, more complex mental states are far from
infallible. But they are still tethered to the world, in so far as
they rest on the unambiguous and direct contact perception and thought
enjoy with their objects.
— Victor Caston, "Phantasia and Thought" in Blackwell Companion To
Main article: Theory of impetus
The Aristotelian theory of motion came under criticism and
modification during the Middle Ages. Modifications began with John
Philoponus in the 6th century, who partly accepted Aristotle's theory
that "continuation of motion depends on continued action of a force"
but modified it to include his idea that a hurled body also acquires
an inclination (or "motive power") for movement away from whatever
caused it to move, an inclination that secures its continued motion.
This impressed virtue would be temporary and self-expending, meaning
that all motion would tend toward the form of Aristotle's natural
The Book of Healing
The Book of Healing (1027), the 11th-century Persian polymath
Avicenna developed Philoponean theory into the first coherent
alternative to Aristotelian theory. Inclinations in the Avicennan
theory of motion were not self-consuming but permanent forces whose
effects were dissipated only as a result of external agents such as
air resistance, making him "the first to conceive such a permanent
type of impressed virtue for non-natural motion". Such a self-motion
(mayl) is "almost the opposite of the Aristotelian conception of
violent motion of the projectile type, and it is rather reminiscent of
the principle of inertia, i.e. Newton's first law of motion."
Banū Mūsā brother, Ja'far Muhammad ibn Mūsā ibn
Shākir (800-873), wrote the Astral Motion and The
Attraction. The Persian physicist,
Ibn al-Haytham (965-1039) discussed
the theory of attraction between bodies. It seems that he was aware of
the magnitude of acceleration due to gravity and he discovered that
the heavenly bodies "were accountable to the laws of physics". The
Abū Rayhān al-Bīrūnī
Abū Rayhān al-Bīrūnī (973-1048) was the first to
realize that acceleration is connected with non-uniform motion (as
later expressed by Newton's second law of motion). During his
debate with Avicenna, al-Biruni also criticized the Aristotelian
theory of gravity firstly for denying the existence of levity or
gravity in the celestial spheres; and, secondly, for its notion of
circular motion being an innate property of the heavenly bodies.
In 1121, al-Khazini, in The Book of the Balance of Wisdom, proposed
that the gravity and gravitational potential energy of a body varies
depending on its distance from the centre of the Earth.[not in
Hibat Allah Abu'l-Barakat al-Baghdaadi (1080–1165)
wrote al-Mu'tabar, a critique of
Aristotelian physics where he negated
Aristotle's idea that a constant force produces uniform motion, as he
realized that a force applied continuously produces acceleration, a
fundamental law of classical mechanics and an early foreshadowing of
Newton's second law of motion. Like Newton, he described
acceleration as the rate of change of speed.
In the 14th century,
Jean Buridan developed the theory of impetus as
an alternative to the Aristotelian theory of motion. The theory of
impetus was a precursor to the concepts of inertia and momentum in
classical mechanics. Buridan and Albert of Saxony also refer to
Abu'l-Barakat in explaining that the acceleration of a falling body is
a result of its increasing impetus. In the 16th century,
Al-Birjandi discussed the possibility of the
Earth's rotation and, in
his analysis of what might occur if the
Earth were rotating, developed
a hypothesis similar to Galileo's notion of "circular inertia". He
described it in terms of the following observational test:
"The small or large rock will fall to the
Earth along the path of a
line that is perpendicular to the plane (sath) of the horizon; this is
witnessed by experience (tajriba). And this perpendicular is away from
the tangent point of the Earth’s sphere and the plane of the
perceived (hissi) horizon. This point moves with the motion of the
Earth and thus there will be no difference in place of fall of the two
Life and death of Aristotelian physics
Aristotle depicted by Rembrandt, 1653
The reign of Aristotelian physics, the earliest known speculative
theory of physics, lasted almost two millennia. After the work of many
pioneers such as Copernicus, Tycho Brahe, Galileo,
Newton, it became generally accepted that
Aristotelian physics was
neither correct nor viable. Despite this, it survived as a
scholastic pursuit well into the seventeenth century, until
universities amended their curricula.
In Europe, Aristotle's theory was first convincingly discredited by
Galileo's studies. Using a telescope,
Galileo observed that the Moon
was not entirely smooth, but had craters and mountains, contradicting
the Aristotelian idea of the incorruptibly perfect smooth Moon.
Galileo also criticized this notion theoretically; a perfectly smooth
Moon would reflect light unevenly like a shiny billiard ball, so that
the edges of the moon's disk would have a different brightness than
the point where a tangent plane reflects sunlight directly to the eye.
A rough moon reflects in all directions equally, leading to a disk of
approximately equal brightness which is what is observed. Galileo
also observed that
Jupiter has moons – i.e. objects revolving around
a body other than the
Earth – and noted the phases of Venus, which
demonstrated that Venus (and, by implication, Mercury) traveled around
the Sun, not the Earth.
According to legend,
Galileo dropped balls of various densities from
the Tower of Pisa and found that lighter and heavier ones fell at
almost the same speed. His experiments actually took place using balls
rolling down inclined planes, a form of falling sufficiently slow to
be measured without advanced instruments.
In a relatively dense medium such as water, a heavier body falls
faster than a lighter one. This led
Aristotle to speculate that the
rate of falling is proportional to the weight and inversely
proportional to the density of the medium. From his experience with
objects falling in water, he concluded that water is approximately ten
times denser than air. By weighing a volume of compressed air, Galileo
showed that this overestimates the density of air by a factor of
forty. From his experiments with inclined planes, he concluded
that if friction is neglected, all bodies fall at the same rate (which
is also not true, since not only friction but also density of the
medium relative to density of the bodies has to be negligible.
Aristotle correctly noticed that medium density is a factor but
focused on body weight instead of density.
Galileo neglected medium
density which led him to correct conclusion for vacuum).
Galileo also advanced a theoretical argument to support his
conclusion. He asked if two bodies of different weights and different
rates of fall are tied by a string, does the combined system fall
faster because it is now more massive, or does the lighter body in its
slower fall hold back the heavier body? The only convincing answer is
neither: all the systems fall at the same rate.
Aristotle were aware that the motion of falling bodies
was not uniform, but picked up speed with time. Since time is an
abstract quantity, the peripatetics postulated that the speed was
proportional to the distance.
Galileo established experimentally that
the speed is proportional to the time, but he also gave a theoretical
argument that the speed could not possibly be proportional to the
distance. In modern terms, if the rate of fall is proportional to the
distance, the differential expression for the distance y travelled
after time t is:
displaystyle dy over dt propto y
with the condition that
Galileo demonstrated that this system would stay at
for all time. If a perturbation set the system into motion somehow,
the object would pick up speed exponentially in time, not
Standing on the surface of the Moon in 1971,
David Scott famously
repeated Galileo's experiment by dropping a feather and a hammer from
each hand at the same time. In the absence of a substantial
atmosphere, the two objects fell and hit the Moon's surface at the
The first convincing mathematical theory of gravity – in which two
masses are attracted toward each other by a force whose effect
decreases according to the inverse square of the distance between them
– was Newton's law of universal gravitation. This, in turn, was
replaced by the General theory of relativity due to Albert Einstein.
Further information: Gravity
As listed in the Corpus Aristotelicum
Generally agreed to be spurious.
Physics (natural philosophy)
On the Heavens
On Generation and Corruption
De Generatione et Corruptione
On the Universe
On the Soul
Parva Naturalia ("Little Physical Treatises")
Sense and Sensibilia
De Sensu et Sensibilibus
De Memoria et Reminiscentia
De Somno et Vigilia
On Divination in Sleep
De Divinatione per Somnum
On Length and Shortness
De Longitudine et Brevitate Vitae
On Youth, Old Age, Life
and Death, and Respiration
De Juventute et Senectute, De
Vita et Morte, De Respiratione
History of Animals
Parts of Animals
De Partibus Animalium
Movement of Animals
De Motu Animalium
Progression of Animals
De Incessu Animalium
Generation of Animals
De Generatione Animalium
On Things Heard
On Marvellous Things Heard
De mirabilibus auscultationibus
On Indivisible Lines
De Lineis Insecabilibus
The Situations and Names
On Melissus, Xenophanes,
Minima naturalia, a hylomorphic concept suggested by
analogous in Peripatetic and Scholastic physical speculation to the
atoms of Epicureanism
a ^ Here, the term "Earth" does not refer to planet Earth, known by
modern science to be composed of a large number of chemical elements.
Modern chemical elements are not conceptually similar to Aristotle's
elements; the term "air", for instance, does not refer to breathable
^ Lang, H.S. (2007). The Order of Nature in Aristotle's Physics: Place
and the Elements. Cambridge University Press. p. 290.
^ White, Michael J. (2009). "
Aristotle on the Infinite, Space, and
Time". Blackwell Companion to Aristotle. p. 260.
^ History of Science
Aristotle vs. The
Physics of Galileo". Archived from the
original on 11 April 2009. Retrieved 6 April 2009.
^ a b "www.hep.fsu.edu" (PDF). Retrieved 26 March 2007.
^ a b c "Aristotle's physics". Retrieved 6 April 2009.
^ Aristotle, meteorology.
^ Sorabji, R. (2005). The Philosophy of the Commentators, 200-600 AD:
Physics. G - Reference, Information and Interdisciplinary Subjects
Series. Cornell University Press. p. 352.
ISBN 978-0-8014-8988-4. LCCN 2004063547.
De Caelo II. 13-14.
^ For instance, by Simplicius in his Corollaries on Place.
^ El-Bizri, Nader (2007). "In Defence of the Sovereignty of
Philosophy: al-Baghdadi's Critique of Ibn al-Haytham's Geometrisation
of Place". Arabic Sciences and Philosophy. 17: 57–80.
Tim Maudlin (2012-07-22). Philosophy of Physics: Space and Time:
Space and Time (Princeton Foundations of Contemporary Philosophy) (p.
2). Princeton University Press. Kindle Edition. "The element earth's
natural motion is to fall— that is, to move downward. Water also
strives to move downward but with less initiative than earth: a stone
will sink though water, demonstrating its overpowering natural
tendency to descend. Fire naturally rises, as anyone who has watched a
bonfire can attest, as does air, but with less vigor."
^ Bodnar, Istvan, "Aristotle's Natural Philosophy" in The Stanford
Encyclopedia of Philosophy (Spring 2012 Edition, ed. Edward N. Zalta).
^ Rovelli, Carlo (2015). "Aristotle's Physics: A Physicist's Look".
Journal of the American Philosophical Association. 1 (1): 23–40.
^ Gindikin, S.G. (1988). Tales of Physicists and Mathematicians.
Birkh. p. 29. ISBN 9780817633172. LCCN 87024971.
^ Lindberg, D. (2008), The beginnings of western science: The European
scientific tradition in philosophical, religious, and institutional
context, prehistory to AD 1450 (2nd ed.), University of Chicago Press.
^ Land, Helen, The Order of Nature in Aristotle's Physics: Place and
the Elements (1998).
^ Tully; Shaya; Karachentsev; Courtois; Kocevski; Rizzi; Peel (2008).
"Our Peculiar Motion Away From the Local Void". The Astrophysical
Journal. 676 (1): 184. arXiv:0705.4139 .
Physics 194 b17–20; see also:
Posterior Analytics 71
b9–11; 94 a20.
^ a b "Four Causes". Falcon, Andrea.
Aristotle on Causality. Stanford
Encyclopedia of Philosophy 2008.
^ Aristotle, "Book 5, section 1013a", Metaphysics, Hugh Tredennick
Aristotle in 23 Volumes, Vols. 17, 18, Cambridge, MA,
Harvard University Press; London, William Heinemann Ltd. 1933, 1989;
(hosted at perseus.tufts.edu.)
Aristotle also discusses the four
causes in his Physics, Book B, chapter 3.
^ a b Hankinson, R.J. "The Theory of the Physics". Blackwell Companion
to Aristotle. p. 216.
^ a b Hankinson, R.J. "Causes". Blackwell Companion to Aristotle.
Parts of Animals
Parts of Animals I.1.
^ Hankinson, R.J. "Causes". Blackwell Companion to Aristotle.
^ a b Henry, Devin M. (2009). "Generation of Animals". Blackwell
Companion to Aristotle. p. 368.
^ Hankinson, R.J. "Causes". Blackwell Companion to Aristotle.
^ a b Caston, Victor (2009). "Phantasia and Thought". Blackwell
Companion to Aristotle. pp. 322–2233.
Aydin Sayili (1987), "Ibn Sīnā and Buridan on the Motion of the
Projectile", Annals of the New York Academy of Sciences 500 (1):
^ Duhem, Pierre (1908, 1969). To Save the Phenomena: An Essay on the
Idea of Physical theory from Plato to Galileo, University of Chicago
Press, Chicago, p. 28.
^ O'Connor, John J.; Robertson, Edmund F., "Al-Biruni", MacTutor
History of Mathematics archive, University of St Andrews .
^ Rafik Berjak and Muzaffar Iqbal, "Ibn Sina--Al-Biruni
correspondence", Islam & Science, June 2003.
^ Mariam Rozhanskaya and I. S. Levinova (1996), "Statics", in Roshdi
Rashed, ed., Encyclopedia of the History of Arabic Science,
vol. 2, pp. 614–642 [621-622]. (Routledge, London and New
Shlomo Pines (1970). "Abu'l-Barakāt al-Baghdādī, Hibat Allah".
Dictionary of Scientific Biography. 1. New York: Charles Scribner's
Sons. pp. 26–28. ISBN 0-684-10114-9.
(cf. Abel B. Franco (October 2003). "Avempace, Projectile Motion, and
Impetus Theory", Journal of the History of Ideas 64 (4),
pp. 521–546 .)
^ A. C. Crombie, Augustine to
Galileo 2, p. 67.
Aydin Sayili (1987), "Ibn Sīnā and Buridan on the Motion of the
Projectile", Annals of the New York Academy of Sciences 500 (1):
^ Gutman, Oliver (2003). Pseudo-Avicenna, Liber Celi Et Mundi: A
Critical Edition. Brill Publishers. p. 193.
^ (Ragep & Al-Qushji 2001, pp. 63–4)
^ (Ragep 2001, pp. 152–3)
^ a b
Galileo Galilei, Dialogue Concerning the Two Chief World
^ a b
Galileo Galilei, Two New Sciences.
Ragep, F. Jamil (2001). "Tusi and Copernicus: The Earth's Motion in
Context". Science in Context. Cambridge University Press. 14 (1–2):
Ragep, F. Jamil; Al-Qushji, Ali (2001). "Freeing Astronomy from
Philosophy: An Aspect of Islamic Influence on Science". Osiris, 2nd
Series. 16 (Science in Theistic Contexts: Cognitive Dimensions):
49–64 and 66–71. Bibcode:2001Osir...16...49R.
H. Carteron (1965) "Does
Aristotle Have a Mechanics?" in Articles on
Aristotle 1. Science eds. Jonathan Barnes, Malcolm Schofield, Richard
Sorabji (London: General Duckworth and Company Limited), 161-174.
Katalin Martinás, “Aristotelian Thermodynamics” in
Thermodynamics: history and philosophy: facts, trends, debates
(Veszprém, Hungary 23–28 July 1990), pp. 285–303.
Theology (unmoved mover)
Ideas and interests
Correspondence theory of truth
Virtue ethics (golden mean)
Philosophy of nature (sublunary sphere)
Potentiality and actuality
Universals (substantial form)
Substance (hypokeimenon, ousia, transcendentals)
Category of being
On the Soul
Alexander the Great
Commentaries on Aristotle
Recovery of Aristotle
Views on women
Aristotle's wheel paradox