In the last two centuries, our world would have been a safer place if philosophers such as Rousseau, Marx, and Nietzsche had not given intellectual encouragement to the radical ideologies of Jacobins, Stalinists, and fascists. Maybe the world would have been better off, from the standpoint of sound practice, if philosophers had engaged in only modest, decent theory, as did John Stuart Mill. Yet, as Ronald Beiner contends, the point of theory is...