“In characterizing an episode or a state as knowing, we are not giving an empirical description of it. We are placing it in the logical space of reasons, of justifying and being able to justify what one says." [1]
Note, there’s nothing too special about knowing. He could also have said believing.
We’re doing something, an act that’s not describing something.
Relates to the scientium mensure quote - we have an example of something (describing knowledge) as something that science is not the measure of all things about.
Rorty characterized Sellars readership as "right wing" (ones who felt the greatest philosophical illumination from “scientium mensura") vs "left wing" (who rally behind the “space of reasons").
The Vienna circle, too, had two wings (the naturalist wing (Neurath) and the empiricist wing (Schlict)) in tension (e.g. empiricists making sense of modal statements). Carnap struggled to hold them together.
Joke: Rorty says “I hope the left and right wing Sellarsians can sort their differences out in the end more peacefully than the left and right wing Hegelians did, who settled it once and for all at a 6 month seminar called The Battle of Stalingrad.”