Both point out that the market is not perfect and there's no denying it. You'll be hard pressed to find any economist who thinks businesses, and even whole markets, make mistakes. But the temporary or systematic failure of a firm, or the temporary failure of many firms (i.e. the market) does not mean there are inherent problems with the system. On the motivations of engaging in investments investors knew little about, Solow writes
Why did I do such a risky and, as it turned out, stupid thing? Well, it had worked in the past, and made a lot of money for many people. If I had backed off, others would probably have continued to make money for a while. I would have looked like a fool, and very likely an unemployed fool.Add "until now." And lots of banks didn't do it: Pittsburgh National, Wells Fargo, JP Morgan Chase, and Bank of America (the last one did, but only after the crisis begun). Now they look like geniuses. Believing firms are so mindless, myopic, and systematically prone to being duped violates basic economic principles of rationality.
Imperfections and information asymmetries always exist. People understand that and people adapt to it. They don't adapt instantly and they don't do it perfectly, but they adapt as well as they can. Solow and Posner seem to agree unless we're talking about regulators. One cannot point to information asymmetry as a key problem and then call for non experts to correct it.
That is not to say regulation never has its place, but the issue is one of costs and benefits. What is less costly to society: the costs of establishing and maintaining the regulation plus the good opportunities regulation renders impossible or the occasional, but vary painful, market corrections that come with no regulation. The answer is not obvious, especially when you consider that people will adapt to the rules. There are many ways around regulation (creating a false sense of security), many ways to game the system (making regulation more costly), and many reasons to embrace prudence when you know one's going to save you if you screw up. The essential mechanism of market self-correction doesn't go away when errors get big, though the additional time it takes to fix itself (increased by uncertainty in the political climate) might fool even famous judges and Nobel Laurettes that it disappears completely.