I don't really buy this, simply because actual investors do not think this way. On public markets at least, there is some expectation that a stock price will ha

I don't really buy this, simply because actual investors do not think this way. On public markets at least, there is some expectation that a stock price will have some relationship to expected future earnings. When the price is out of whack with those future earnings, the stock is under- or over-valued - and I would say that this is objectively true even when there is no way of knowing. Of course, there very often is a way of at least taking an intelligent guess, which is why Warren Buffett is so goddamn rich, for one. Otherwise, we are left believing obvious absurdities: for example, somebody who bought Bear Stearns at $60 on March 13 2008 got just as good a deal as somebody who bought Bear at $3 on March 17; Bernie Madoff's fund management services were worth every penny until his arrest; etc. There is nothing 'subjective' about either Bear's hiding of the worthlessness of its subprime books or the fraudulence of Madoff's scheme.