 Given the constraints of the present entry, we shall not attempt to discuss this question in any detail; instead, we present only the barest of outlines. After all, modern logicians and philosophers of logic have not yet come to agreement about the proper conception of logic.  Many have a conception of logic that is yet different from both Kant’s and Frege’s, one that was, to some extent, anticipated by Bolzano, namely, that logical concepts and laws remain invariant under reinterpretation of the non-logical constants or under permutations of the domain of quantification. But since this modern conception is still a matter of debate, it may be that elements of Frege’s conception will yet play a role in our understanding of what logic is.