Obama's Press Conference: Bad Reasoning

At his recent press conference, President Barack Obama said this about Republicans' refusal to raise taxes:

"I don't think that's a sustainable position. And the truth of the matter is, if you talk to Republicans who are not currently in office, like Alan Simpson who co-chaired my bipartisan commission, he doesn't think that's a sustainable position. Pete Domenici, Republican, co-chaired something with Alice Rivlin, the Democrat, says that's -- he doesn't think that's a sustainable position. You can't reduce the deficit to the levels that it needs to be reduced without having some revenue in the mix."

And he said this about continued U.S. military involvement in Libya:

"I think when you have the former Republican nominee for President, John McCain, and the former nominee for President on the Democratic side, John Kerry, coming together to support what we're doing in Libya, that should tell the American people that this is important. And I very much appreciate their efforts in that regard."

In each case, Obama is committing the "even my enemy agrees" fallacy (AKA the argumentum ad hostes: argument to the enemy). That is, he's arguing that his position on these issues -- raising taxes and military intervention in Libya -- is more acceptable given that his opponents (Simpson and Domenici regarding taxes, McCain regarding Libya) agree with him.

Obama has resorted to this kind of flawed reasoning previously, as have opponents of collective bargaining (and columnist Ezra Klein also invoked a version of it). But it's not valid reasoning. Just because someone who typically disagrees with me accepts my position that, say, the Earth is flat, doesn't make that position more plausible. Agreement between opponents is not a point in favor of any position whatsoever.

Typically when Republicans support a policy, Obama doesn't say, "Hey, this must be the right policy, because Republicans support it." How does this reasoning become any more plausible when Republicans support one of Obama's ideas? If it's right to raise taxes, the reasons in support of that have nothing to do with whether or not two people agree that it's the right thing to do even though they usually disagree on other things. The same goes for bombing Muammar Gaddafi's regime in Libya.

Obama lays out other arguments in favor of raising taxes and bombing Libya. He should stick to those arguments, rather than employing the flawed argument that "my enemies also agree it's the right thing to do".