I just finished Nassim Nicholas Taleb's Fooled by Randomness, which is one of those books that lets you trade a little happiness for a lot of knowledge. His thesis is that we overestimate the role of skill and seriously underestimate the presence of luck, because we're wired to see causality and consistency when there's only randomness.
That's a good thing to keep in mind, especially in the parts of the book that focus on short-term news and short-term price swings rather than long-term trends. The other day, I bought a stock that, for no particular reason, jumped 6% two days after I purchased it. I'd like to imagine that this move confirmed my investment thesis and demonstrated my skills, but a 6% move on essentially no news is probably just a random fluctuation that could have just as easily gone the other way.
The book has a few weaknesses, though. Taleb insists on treating investment as a competition and a psychological exercise, and while it can be both of these things, I treat it as simply the act of exchanging a sum of money for something of slightly greater value, with the hope of realizing that value. From that perspective, the question isn't "Who is the best?" or "How do I measure my skill compared to my luck?" It's "What can I do to get the highest possible return -- and which actions are likely to increase my returns?"
Taleb and I would agree that the person with the highest five-year return over the last five years is not necessarily the best investor -- and is probably the most leveraged and thus the most likely to eventually blow up. But if he and I both considered an investor with slightly above-average returns (15% per year, say) who, before buying stocks, thoroughly read their financial statements and only purchased stocks he felt would grow faster than the market but which traded at a lower price/earnings ratio, Taleb might attribute the extra return to luck -- I'd attribute it to effort. I'd hope that if we make it more explicit ("There is value in knowing what you're buying" versus "Learning about the stocks you're buying is a waste of effort,") he'd agree -- but you wouldn't know it from the book.
One last flaw: he attributes Microsoft's success to path dependence -- once you've picked a software package, the cost of switching to another is high enough that you may stick with an inferior product despite knowing about better opportunities. This is ironic, inasmuch as Microsoft's biggest innovation was that you could mass-produce software and sell it for multiple systems, instead of crafting it bespoke. This brought prices down by a few orders of magnitude, and played a major role in making computers ubiquitous. Meanwhile, they offered their office applications for several operating systems (DOS, Windows, Apple, OS/2), and sold operating systems with several paradigms at once -- graphical user interfaces (Windows), a proprietary command-line interface (DOS), and even Unix (Xenix).
This played a major role in their success. Before Microsoft, buying a computer meant buying into a single paradigm and selling your right to switch cheaply. After Microsoft, buying a computer probably meant being able to use native formats and programs -- or switching into the nearly ubiquitous Microsoft options.
And then they stopped. Instead of breaking down path dependence, Microsoft started fencing off their path and locking the gates behind them -- they sold their Unix product, they dropped Internet Explorer support for Macs, and they kept tight control over Outlook so the cost of communicating with a Microsoft user was, approximately, the cost of becoming a Microsoft user yourself.
And then Sun Microsystems started supporting the OpenOffice.org project, which creates a Microsoft Office clone that runs just about anywhere. And Novell created Evolution, which does about the same thing for Outlook. Both companies saw an opportunity to break down Microsoft path dependence -- they followed the classic entrepreneurial equation (10% of a market that's 90% smaller than it used to be is a lot better than 0% of the market that existed before). Path dependence explains some of Microsoft's success, but a lot more of it was thanks to getting mediocre software done before the best software was ready -- and making some slick deals with IBM, too.
(Don't even start with Taleb's other example.)
I'd be surprised if a book that tried so hard to be iconoclastic didn't contain at least a few errors. Taleb wrote it because people see signal where there's only noise -- which makes it a bit ironic that his faith in the ubiquity of noise made him blind to some pretty blatant signals.