The general topic is fiscal policy, and the specific topic is Brad DeLong's claim to speak for sensible, centrist technocrats. It appears that DeLong defines a sensible, centrist technocrat as someone who finds the case for Keynesian fiscal policy compelling in today's environment. In that case, I am not a sensible, centrist technocrat, but you knew that already. After all, when the sensible, centrist technocrats backed TARP, I was vehemently opposed.
There is a deeper question that Steve and Tyler raise, which is whether an economist should propose the ideal policy, knowing that it will be rejected, or meet the political situation half-way. One not-very-charming reason for proposing politically infeasible policies is to put yourself in a safe position to say I told you so. However, there are also not-very-charming reasons for proposing politically palatable policies.
The political market will select for policies that raise the status of the political leaders who advocate them. There is not much one can do about that.
I think that sensible, centrist, technocrats are a curse, rather than a blessing (insert well-known William F. Buckley quote here). But there is not much one can do about that, either.