Magick is interesting stuff....I tend to agree with Crowley's definition that magick is the application of Will to effect a desired change. This definition isn't quite consonent with a probabilstic universe, however - so I would say that it's the application of Will to effect a change in the probabilities.

Some people may think that this is a copout - that magick should operate absolutely. I question this approach - if the universe is probablilistic, nothing will have an absolute certainty of working - or even existing.