 Kant has been traditionally taken to be offering a method of avoiding the insidious “transcendental illusion” that gives rise to metaphysics. Read in this way, Kant’s Dialectic offers a criticism not only of the specific arguments of metaphysics, but also of transcendent, metaphysical (speculative or theoretical) interests and propensities themselves. This certainly accords with much in the Dialectic, and specifically with Kant’s well-known claim that knowledge has to be limited to possible experience. Kant, however, complicates things somewhat by also stating repeatedly that the illusion that grounds metaphysics (roughly, that the unconditioned is already given) is unavoidable. Moreover, Kant sometimes suggests that such illusion is somehow necessary for our epistemological projects (cf. A645/B673). In this connection, Kant argues that the transcendent ideas and principles of reason do have a positive role to play in knowledge acquisition, so long as they are construed “regulatively” and not “constitutively.” He thus suggests that rather than jettison the ideas of metaphysical objects (something, it seems, he does not think we are in a position to do), it is best to identify the proper use and function of these ideas and principles. This critical reinterpretation involves the claim that the ideas and principles of reason are to be used “regulatively,” as devices for guiding and grounding our empirical investigations and the project of knowledge acquisition. What the ideas do not do, according to Kant, is provide the concepts through which we might access objects that could be known through the speculative use of reason.