Wrong is right?

From today's Paul Krugman column:

I like Ezra Klein; I find his blog an extremely useful source, and his analysis of health-policy issues in particular is invaluable. But my jaw dropped when I read this:

Just over a year ago, I wrote a column praising Rep. Paul Ryan’s Roadmap. I called its ambition “welcome, and all too rare.” I said its dismissal of the status quo was “a point in its favor.” When the inevitable backlash came, I defended Ryan against accusations that he was a fraud, and that technical mistakes in his tax projections should be taken as evidence of dishonesty. I also, for the record, like Ryan personally, and appreciate his policy-oriented approach to politics. So I believe I have some credibility when I say that the budget Ryan released last week is not courageous or serious or significant. It’s a joke, and a bad one.

Ezra is right about this plan — but the Roadmap was also a bad joke. And Ryan has been a disingenuous flake all along; if you didn’t see that from the start, it makes you less, not more, credible.

This reminds me a bit of the way things were in 2004-5, when it was more or less openly acknowledged that you had to have been wrong about Iraq to be considered serious on national security issues.