Many discussions of probability start with the examples of fair coin flips. In reality, however, coin flips are instruments: at the beginning of football games, coin flips are instruments we use to deal with the problem of needing to start somewhere but not caring who starts; flipping a coin to see who has to mow the lawn is an instrument for dealing with being unable or unwilling to figure out who ought to have to do it (or for some other reason). Any example of true randomness taken from art will be a case of randomness used as an instrument to prove something since we can’t avoid the intention of a human being at the base of the action. In this sense “pure chance” (where pure means “unmixed with another”, namely, intention) is simply a contradiction. There is no such thing.
When studying probability, we separate out this instrumental character of chance. It is not clear, however, if by doing so we separate out something essential to chance. The assumption is that if we can separate out “pure chance” in our thought then there must be such a thing as “pure chance” at work in nature. If this is incorrect, it would not be the first time we thought that since we can separate something in thought that it was therefore separate in reality. This notion of “pure chance” might be the evil-reverse image of Plato’s world of forms- a supposedly pure world of complete unintelligibility.
It stands to reason that if chance must be an instrument in human affairs that it is an instrument in natural ones. Emission of seeds in animals and plants is a way of using chance as an instrument (the rareness of a chance outcome is taken for granted in the emission of a billion seeds) and the chance motion of molecules promises that they will be uniformly spread out or distributed, the same way that a cement mixer uses chance to evenly mix in gravel (if all water molecules did not move randomly, but could “clump together” and move as one, there might easily be huge holes opening up in the water, or huge hills and dips forming in it at random times)
Just Thomism 
gimmesometruth (@chrispkonkol) said,
October 28, 2013 at 8:14 pm
I wonder whether what we take as pure chance can be taken as the work of God, also completely undetectable. It can be argued that there is no such thing as pure chance, or can argue that it permeates our universe. Sounds to me that there is something unresolvable here. Can’t say it exists, can’t say it doesn’t. Welcome to the wormhole.