Which Textbook? Foundations of Economics

In a brief post lauding his insights into the supposed virtues of inflationary expectations, Paul Krugman says, "As far as I know, among basic textbooks only Krugman/Wells even talks about the liquidity trap. . ." Actually Foundations of Economics talks about it, and explains some of its weaknesses as a theory.

I argue in part that:

The concern over the liquidity trap is only as valid as the liquidity preference theory of interest. What we have already learned about the interest rate should be enough to make us question the soundness of this theory. We have seen that the interest rate is not merely a monetary phenomenon, but a time phenomenon. It is the price of present money in exchange for future money. Therefore, the interest rate is determined by people’s subjective time preferences, not the stock of and demand for money.