The Paradox of Kant's Public Use of Reason

For example, for Kant, theological faculty, law faculty and so on. This all is private use of reason because they are not free to question their presuppositions. We should withdraw from the particular social order and act directly as singular universals. How do we guarantee that the public use of reason is really public? By linking it to a social group class, however you call it, which on account of its specific position stands for universality. The idea is that this is basic insight of Marx. Unversality doesn't mean, I'm particular, you're particular, you’re particular, but we try to abstract our differences and see what we have in common.