Paradoxical theories of language, knowledge, and the absurd

My mom points out "the paradox of 'insisting' that words have no 'fixed or stable set of meanings'":

If you really believed what you are insisting, you wouldn't be insisting, you'd be, perhaps, entertaining a suggestion or toying with a notion or musing about the possibility, now wouldn't you?

She's reacting to this description posted on a wall in the Art Institute of Chicago describing an artwork by Bruce Nauman:

Human Nature / Life Death . . . insists on language's inability to deliver a fixed or stable set of meanings, conveying a deep suspicion about what constitutes truth, especially in the public realm.

She adds a great detail:

[W]hen I voiced these thoughts (to Meade) the museum guard overheard, laughed, and nodded knowingly.

It reminds me of one of my philosophy professors from back when I attended the University of Wisconsin, Keith Yandell, who has a knack for devastatingly concise refutations of theories that contradict themselves. For instance, he defined empiricism as the theory that we can only gain knowledge through sensory experience. Then he pointed out that this theory itself is not known to be true through sensory experience.

Another example of this kind of paradox (is there a name for it?) is the problem of the absurd. It's supposed to be a profound problem that our lives are "absurd," in the philosophical sense. That is, you take your life very seriously from day to day, but you can also take a step back and wonder if the whole thing is ultimately pointless, meaningless.

Now, that problem -- the problem of the absurd -- is itself a paradox, but it's not the kind of paradox that this blog post is about. The paradox I want to focus on is one that Thomas Nagel pointed out in his wonderful book Mortal Questions. The problem of the absurd contains a couple of subtle internal contradictions. And if you grasp these contradictions, you may start to feel that the absurd is not such a problem at all -- or at least, not a deeply troubling one. Nagel explains:

[A]bsurdity is one of the most human things about us: a manifestation of our most advanced and interesting characteristics. . . .

If . . . there is no reason to believe that anything matters, then that does not matter either, and we can approach our absurd lives with irony instead of heroism or despair.