Professor Proops's research foci include Early Analytic philosophy (especially, Frege, Russell and Wittgenstein) and Kant's theoretical philosophy. He has worked on Russell's logicism and the conception of logic that lies behind it, and on Russell and Wittgenstein's logical atomism. He is currently working on a book on Russell’s theory of descriptions. His work on Kant focuses on the Critique of Pure Reason, and, in particular, on Kant's conception of analytic judgment and the Transcendental Deduction of the Categories.