The Atomists
Again, even if it is quite impossible both for what
does not exist to come into being and for what
exists to perish, why should not some things
nevetheless be generated and others eternal as
Empedocles says? For he too, having admitted all
this –namely that
from what does not exist nothing can come into being, and
for what exists to be destroyed is impossible and
unaccomplishable—
Nevertheless he says that some things are eternal
while others come and have come into being from
them.
Aristotle, On Melissus
Democritus thinks that the nature of eternal
things consists in small substances, infinite in
quantity, and for them he posits a place, distinct
from them and infinite in extent… He thinks
that he substances are so small that they escape
our sense, and that they possess all sorts of
forms and all sorts of shapes and differences in
magnitude.
From them, as from elements, he was able to
generate and compound visible and perceptible
bodies. The atoms struggle and are carried about
the in the void because of their dissimilarities
and other differences mentioned, and as they are
carried about they collide and are bound
together… up to the time when some stronger
force reaches them from their environment and
shakes them and scatters them apart.
Aristotle, Fragment 208
x is an atom =df x has no parts (other than itself).
Atomism: Everything is either an atom or
composed of atoms.
Democritean Atoms are:
(i) eternal,
(ii) small,
(iii) infinite in number,
(iv) unobservable,
(v) differently shaped, and
(vi) indivisible.
Heraclitus’ Flux Argument
1. A river is nothing more than a body of flowing
water.
2. A body of flowing water does not exist for
more than a moment.
3. If (1) and (2), then a river does not exist for
more than a moment.
4. If a river doesn’t exist for more than a
moment, then the Doctrine of Flux is true.
5. The Doctrine of Flux is true.
Parmenides’ Argument Against Generation
1. If something is generated, then either (a) it
came from nothing or (b) it came from
something that already existed.
2. It is impossible that (a).
3. It is impossible that (b).
4. Everything is ungenerated.
There is a difficulty if one supposes that there is a body or
magnitude which is divisible everywhere… suppose it to
have been divided. What will be left? A magnitude? That
is not possible; for then there will be something that has
not been divided, but we supposed it divisible
everywhere. But if there is to be no body or magnitude
left and yet the division is to take place, it will either
consist of points and its components will have no
magnitude, or else they will be nothing at all so that what
would come to be, and be composed, from nothing and
the whole body would be nothing but an appearance…
So… necessarily there are indivisible bodies and
magnitudes.
Aristotle, On Generation and Corruption
Democritus’ Argument for Atomism
1. If there’s a body not composed of atoms, then
it could be divided infinitely many times.
2. If it could be divided infinitely many times,
then either (a) it is composed of unextended
points, or (b) it is composed of nothing.
3. No body is composed of unextended points.
4. No body is composed of nothing.
5. Every body is composed of atoms.
Democritean Atoms are:
(i) eternal,
(ii) small,
(iii) infinite in number,
(iv) unobservable,
(v) differently shaped, and
(vi) indivisible.
x is composed of atomless gunk =df all of x’s
parts have parts.