If by "he," you mean Mankiw, I agree. But I think you probably mean mikeryan. I don't think he was talking about a marginal dollar. His point was that the firs

If by "he," you mean Mankiw, I agree. But I think you probably mean mikeryan. I don't think he was talking about a marginal dollar. His point was that the first $12k ($13k in 2010) gifted are taxed differently than dollars beyond that threshold. I suppose the real question is the relative importance of the behavior at the margin versus the behavior for the first dollar. For the ultra-rich, $13k is obviously irrelevant, but for someone near the $250k annual income threshold like Mankiw, I don't think it is. The present value of $12k per year given every year for 30 years is substantially larger than the same amount invested and then hit by estate tax at year 30.