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 thatfrom 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 a proper part of y =df x is a part of y and x isn’t identical to y.x is an atom =df x has no proper parts.Atomism: Everything is either an atom or composed of atoms.

Democritean Atoms are:(i) eternal,(ii) infinite in number,(iii) small,(iv) extended,(v) differently shaped, and(vi) indivisible.

Heraclitus’ Flux Argument

1. TR is YR. 2. TR is TW3. YR is YW4. [So] TR is YW5. [So] YW is TR6. [So] YW is TW.7. YW isn’t TW.8. [So] YR isn’t TR. 9. If (8), then the Flux Thesis is true.10.The Flux Thesis is true.

Parmenides’ ArgumentAgainst Generation

1. If something is generated, then either (a) it comes from nothing or (b) it comes from something else.

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.

Aristotle, On Generation and Corruption

Democritus’ Argument for Atomism

1. If there is a body that is not composed of atoms, then it could be divided infinitely many times.

2. If a body 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.

• x is composed of atomless gunk =df all of x’s parts have proper parts.