"But the real uncertainty principle is more precise than that. It states that while some phenomena produce a definable range of possible outcomes, it is impossible to infer from the outcome which single unique event actually produced it. This has evolved, Mr. Lindley says, into "a practical, workaday definition of the uncertainty principle that most physicists continue to find convenient and at least moderately comprehensible as long as they choose not to think too hard about the still unresolved philosophical or metaphysical difficulties it throws up."
http://www.nytimes.com/2007/02/12/books/12masl.html
