Ancient Greek philosophy had two concepts of chance, both causes of effects that happen incidentally, but differentiated in the second book of Aristotle's Physics as follows:
- Tyche (or "luck") operates in the mind.
- Automaton (or "chance") operates in the realm of nature.
To many earlier Greek philosophers chance did not exist. One of the surviving fragments of Leucippus says: "Nothing occurs at random, but everything for a reason and by necessity". To the atomists the world was completely deterministic. However, Democritus also claimed that chance (automaton) caused the original creation of "the heavenly spheres and all the worlds", i.e. that existence itself has no prior or determining cause, although everything that has happened since is deterministic. To Aristotle on the other hand, both tyche (luck) and automaton (chance) are everyday phenomena. However, for Aristotle chance events were not uncaused, they were simply the effect of the concurrence of two causal sequences. Thus a stone falling that happens to hit a tree is a chance event, although the falling of the stone and the growing of the tree are both determined events.
