Are markets random?

The question above should be more specific and say: Are markets totally random? Obviously, there is a lot of randomness in financial markets but is it all random?
If the answer to that very big question were a resounding yes, that would mean anybody trying to use charts (or more generally past data) to trade is doomed to failure. That's what proponents of the efficient market theory and its relative, the random walk theory believe.
So I think that, far from merely being a rhetorical question, it is of existential importance to any practitioner of technical analysis.
A lot of evidence has turned up in the past 20 years that seemed to disprove or at least seriously damage the random walk and the efficient market theories, none more potent than the crash of October 1987. As any self-respecting statistician will tell you, if the markets actually followed a random walk, that crash would have never happened.
For more background information about this most interesting of subjects, I found this on that most hated (but most useful) of sources, Wikipedia:

"The mathematical characterisation of stock market movements has been a subject of intense interest. The conventional assumption that stock markets behave according to a random Gaussian or normal distribution is incorrect. Large movements in prices (i.e. crashes) are much more common than would be predicted in a normal distribution. Research at the Massachusetts Institute of Technology shows that there is evidence that the frequency of stock market crashes follow an inverse cubic power law.[6] This and other studies suggest that stock market crashes are a sign of self-organized criticality in financial markets. In 1963, Benoît Mandelbrot proposed that instead of following a strict random walk, stock price variations executed a Lévy flight.[7] A Lévy flight is a random walk which is occasionally disrupted by large movements. In 1995, Rosario Mantegna and Gene Stanley analyzed a million records of the S&P 500 market index, calculating the returns over a five year period.[8] Their conclusion was that stock market returns are more volatile than a Gaussian distribution but less volatile than a Lévy flight.
Researchers continue to study this theory, particularly using computer simulation of crowd behaviour, and the applicability of models to reproduce crash-like phenomena...."

I actually found the article they're mentioning about markets and power-laws.

For what appears (to my untrained eyes) to be an impressively conclusive proof of the non-randomness of markets, you can check out this paper titled, oddly enough:
Stock Market Prices Do Not Follow Random Walks: Evidence from a Simple Specification Test. Be warned: it is math-heavy.

Despite all the new recent research, followers of the Random Walk Theory have been, so far, impervious to self-doubt. Their argument goes something like this: outliers, nothing but outliers!