“Speculative is to be understood here in its Hegelian sense as opposed to positive, that is, as opposed to that which may be defined by virtue of certain presuppositions which remain implicit. The elucidation of these presuppositions can only be accomplished through an experience which relates the positive to the presuppositions which was the conditions of its definition. This experience is the transgression of the limit between the positive and its condition. It is precisely by virtue of what is articulated through speculative experience that the discourse of the speculative proposition is to be distinguished from theoretical enterprises which are content to bring together different positive fields, and to pass from one to another by a transference (metaphora) which produces a synthesis in the metaphor and not in the concept.”

"Metacritique: The Philosophical Argumetn of Jürgen Habermas, pp. 27-28."