I'm an agnostic on withdrawing troops from Iraq, but criticism of this idea has involved some bad arguments.

Norman Geras writes,

Anyone arguing for a withdrawal of coalition forces from Iraq, whether tomorrow, in six months, or at any date determined in advance rather than set by the demands of the situation and the democratically expressed will of the Iraqi people, needs to support and explain persuasively one of the following hypotheses. (1) That the presence of coalition forces is the main substantial cause of the problems in Iraq today, so that their withdrawal will more or less quickly lead to a radical improvement there. (2) That though this is not the case and therefore not the prospect, however bad things might be after a withdrawal they are unlikely to be worse than they are now. (3) It is not for us to care what would happen in the event of an early withdrawal, bad as the situation may then get. The intervention has been a disaster, it's time for us to get out, and the Iraqis must be left to sort out the mess as best they can.

No. It is also perfectly possible to argue that the continued US force presence is not helping. It is quite clear that the presence of US forces in Iraq is viewed by many as an "occupation," and that it fuels Islamic fundamentalism throughout the middle east. On the other hand, its also quite clear that US troops bring much-needed law and order to Iraq. Whether these two factors balance to our advantage, I do not know; but I can quite understand those who look at Iraq's progression over the past couple of years and think that the presence of US forces is doing more harm than good (most Iraqis routinely say in opinion polls that they want the US to leave immediately).

Anyway, the framing of the question by Geras (and by Bush) is wrong. Even the house resolution on withdrawal sponsored by Rep. Murtha does not ask for a specific date on withdrawal. I doubt that the adoption of a flexible withdrawal strategy, adaptable to the exigencies of the situation, would raise any controversy on the far left.