An interesting analysis of MPCs

Krugman's take on how the MPC might be higher in a recession (and a liquidity trap) as opposed to "normal" times.

So whereas someone who can borrow and lend freely will spend very little of a temporary rise in income, someone who is liquidity-constrained — wanting to spend more right now, but unable to borrow — will spend all of that temporary rise.

The graphs in the link help illustrate why this can be true. Also note that he is using a dynamic model - usually the tool of the neoclassicals - and not some trumped-up "in the long run we're all dead" argument. It also says a thing or two about why tax cuts (or, equivalently, transfers) to the lower segments of the income distribution might have a greater macroeconomic impact.

A thing or two on the Bush tax cuts here.