We have made some judgments as to the prominence of each premise in the debate around the TPC analysis. This is reflected in the relative scoring of each premise using our rating system - the most heavily contested premises appear on top in the Outline and Box visualizations, and have thicker connecting arrows in the Bubble views.

On pages 5 and 6 the TPC paper states:

"The key intuition behind our central result is that, because the total value of the available tax expenditures (once tax expenditures for capital income are excluded) going to high-income taxpayers is smaller than the tax cuts that would accrue to high-income taxpayers, high-income taxpayers must necessarily face a lower net tax burden. As a result, maintaining revenue neutrality mathematically necessitates a shift in the tax burden of at least $86 billion away from high-income taxpayers onto lower- and middle-income taxpayers. This is true even under the assumption that the maximum amount of revenue possible is obtained from cutting tax expenditures for high-income households."




Various facets of this argument have been disputed, including the cost of the marginal rate cuts and the extent of available high-income tax expenditures available to fund the rate cuts. However it is probably fair to say that the bulk of argument has been around the broad economic effects flowing from fundamental tax reform. The TPC model has been criticized as inadequate for performing an essentially 'static' analysis that assumes little impact on GDP, labor supply and capital formation flowing from tax reform. The critics strongly criticize the TPC author's assumptions in this regard and have produced alternative estimates based a different modeling approach. The TPC, for its part, has defended its approach both in the original paper and subsequently.

Several critics have also raised the choice of $200,000 as the threshold below which people are to be considered low to middle class, and therefore to be protected from any additional tax impost. Harvard's Martin Feldstein, for example, has done his own analysis based on a $100,000 threshold. The obvious objection to this line of criticism is, of course, that Romney himself has set the $200,000 threshold. However it seems exploring this further as there is clearly room for legitimate argument about what constitutes high-income (and maybe scope for compromise at some point).

In order to come to grips with these arguments we have identified four key claims that underpin the TPC analysis. We then map the criticisms that have been raised to each premise, rebuttals of the criticisms, rebuttals of rebuttals - and so on to produce an 'argument tree'.

Broadening