It's impossible to point out that someone is blatantly lying without drawing attention to the fact that they are the sort of person who would blatantly lie.

Character and speech are inseparable. As the line from Shakespeare says "Speak, so that I may see thee."

Indeed, we are constantly evaluating the intelligence, integrity, goodwill, and authority of people based—in large part—on what they say.

It's absurd to think that we cannot demolish an argument as dishonest, stupid, ill-informed, or made in bad faith because doing so would inevitably imply the same of the speaker.

One of the he best reasons for maintaining a culture of free speech is that it permits the dangerous idiots to self-identify.

Not authority; credibility. It's a nitpick, but the distinction is important when we're discussing government agents. Credibility is essentially rhetorical authority ("I am willing to take your word because I consider you an expert in the relevant domain"), rather than the kind of authority derived from official bestowment of power.