I made this point recently and I think it's worth repeating. If there is any disparity in the application of labels to describe political persuasion, it might be due to the fact that "liberal" has taken on negative connotations in today's environment, while "conservative" has not. The alleged disparity then might simply be due to the talking head's reluctance to apply what might be seen as a pejorative in some circles.

Further, even if there is a disparity or double-standard in the application of labels, that by itself does not necessarily prove the argument that the media is biased.

Without specific examples of the alleged bias to examine, and - more critically -without a universal understanding of what the bandied-about labels really mean, I don't think you can really make the case one way or the other.

There is no mathematical precision to the meanings of words. However, Formal Logic attempts to systematize the evaluation of statements. Valid arguments cannot contain ambiguous statements or equivocation.

sp