In A Realist Theory of Science, Roy Bhaskar provides several transcendental arguments for critical realism – a position Bhaskar himself characterized as transcendental realism. Bhaskar provides an argument from perception and from the intelligibility of scientific experimentation, maintaining that transcendental realism is necessary for both. I argue that neither argument succeeds, and that transcendental idealism can better vindicate scientific practice than Bhaskar’s realism. Bhaskar’s arguments against the Kantian view fail, for they misrepresent the transcendental idealist position. I conclude that, if they wish to retain their theoretical commitments, critical realists ought to be transcendental idealists.