1. The Atomist World
Consistent Development of alternative world view from about 6th century BC to 1st century AD

2. Basic Concepts
The Universe is in a constant state of transformation (how anti-Aristotelian can you get than that!)
There is an infinite number of atoms and they are in constant movement in an infinite void.
Collisions between atoms form complex bodies.

3. Atom Dynamics
some atoms may have "hooks" and attach themselves readily to atoms that have "handles"; others are "smooth" and resist formation into larger units
The shapes fall into certain and often complementary categories, and as the atoms collide they tend to form the same basic structure again and again (e.g, "people", "trees", etc)
This makes the Cosmos a statistical outcome!  This means that determinism does not exist

4. More Dynamics
All such qualities as heat, color, taste and so on are derived from, and reducible to, differences in the primary properties of atoms such as shape and position.
The atoms fall in one direction in straight lines and equally fast.

5. Problems with these dynamics
If the atoms all fall in one direction, how can they possibly interact/collide?
Epicurus: there must be a built-in “swerve” that occurs at random intervals (note this invokes an ad hoc device, just like the introduction of epicycles)
Implication: the visible world is a consequence of random collisions and fortuitous combination of atoms.

6. Atomism can lead to paradoxes
Logic and order: nothing occurs at random so there are no chance occurrences and everything happens by necessity.
Is there any purpose or intention in the universe? Atomists: NO -- This is not accepted by culture as culture interprets this as the lack of free will.
Democritus says: we are “cut off from the real” meaning we are unable to have certain kinds of knowledge. Hence we rely on perception of things and what others think is “true”; this then becomes the conventional wisdom as truth paradigm

7. On necessity and the rejection of Free Will
[Democritus held that] ...everything that happens, happens of necessity. Motion is the cause of the production of everything, and he calls this necessity.[Diogenes Laertius, Lives,“Democritus”]
Cicero and following Aristotle, and denying 'free will'. "Epicurus saw that if the atoms traveled downwards by their own weight; we should have no freedom of the will [nihil fore in nostra potestate], since the motion of the atoms would be determined by necessity." 

8. The question of the void
To Aristotle the void was a logical impossibility:
How could the Prime Mover communicate to the other spheres if they were not in Contact?
FORCE = RESISTANCE X SPEED, therefore by logic, 
if a Void exists, an object falling through the void would achieve an infinite speed and hence an infinite mass - this is logically impossible
So there you have it.  THERE CAN BE NO VOID!