Perhaps I too eagerly agreed to disagree with Matt Yglesias about whether or not Republicans can be said to have lied about Harry Reid’s high-speed rail plans. An old friend just emailed me this chestnut. Here’s Yglesias writing about a legislative attempt to fund high-speed rail in California last year:

On the idea that ridership estimates are unrealistically optimistic, it seems to me that the sad reality of politics is that it would be irresponsible for advocates of any large-scale infrastructure project to do anything other than present unrealistically optimistic measures. For better or for worse, that’s politics.

So what’s Yglesias’s standard for what constitutes lying here? If a politician who is in favor of a high-speed rail project willingly presents unrealistic information about its public benefits, “that’s politics”? But if a politician opposed to a high-speed rail project argues against it by overstating the cost — regardless of whether they’re simply mistaken about the details — Yglesias says that’s lying.

Huh.