Two others that come to mind are Moliere and Orwell. In Tartuffe, Moliere's attacks on religious hypocrisy and the strict social order certainly mirror progressive thinking for his time. Orwell, it seems to me, would be considered progressive in his defense of individual freedom when it is threatened or crushed by the state and in his assessment of the politics of his day that led him to anticipate the growing power of the state over the individual. 1984 champions the individual and certainly sounds the alarm regarding oppression through political power. Also, in "Shooting an Elephant," Orwell explains exactly how and why he came to view colonial imperialism as an inherently evil political system.