The most common argument against the mandate is that in giving Congress the power to regulate interstate commerce, the founders didn't create the authority for the federal government to regulate inaction. In other words, they say citizens can't be compelled to participate in interstate commerce, such as buying health insurance. Most legal scholars disagree with this interpretation ... — TPMSounds suspiciously like wishful thinking* to me.
* Perhaps even magical thinking.
Incidentally, here is Georgetown law professor Randy Barnett's very recent paper (h/t David Ziemer) on the individual mandate, Commandeering the People: Why the Individual Health Insurance Mandate is Unconstitutional. It's comprehensive, fairly devastating, and has already been cited approvingly by the district court in Florida by way of rejecting the federal government's taxing power argument.
Read it and weep, I'm afraid.