Why would a philosopher take an artist seriously? Nietzsche on Wagner, Heidegger on Hölderlin, Adorno on Schönberg.

The centrality to philosophy of the relation between philosophers and artists is as old as philosophy itself. Regardless of whether one accepts Arthur C. Danto's claim that 'philosophy down the ages has consisted in placing codicils to the platonic testament', it is difficult to ignore the challenge the ancient Greek thinker posed when he excluded artists from his Republic. My thesis takes up this challenge head-on, critically asking why a philosopher would take an artist seriously, why addressing artists is so essential to engaging with society and even the world.
As it turns out, this question itself involves several queries. The first wants to understand what it means to take someone seriously at all, to understand that to take seriously is to run the risk of taking too seriously, and thereby to fall into ridicule.
The second links these insights into seriousness' non-seriousness to the particular case of philosophers and artists. This is to recognize that for a philosopher the recourse to the artist is a claim about the seriousness, not just of the artist, but also of the world itself. It is the claim that our conception of the world is at stake, is serious. Thirdly, we must account for the model of art and artists in this conception, and grasp that the exemplarity of artists is simultaneously their counter-exemplarity. As such, the exemplarity of the artist is indeed his inappropriateness to the Republic, but also the basis for there being any Republic at all.
In order to address these queries, the thesis focuses on three prototypical examples: Friedrich Nietzsche on Richard Wagner, Martin Heidegger on Friedrich Hölderlin, and Theodor Adorno on Arnold Schönberg. In all three cases, the recourse to the artist is central to the philosopher's greater philosophical project, and for each, the artist stands as a potential model for our necessary engagement with the world.