Synchronic irregularities and restored coherence
Much like abductive reasoning in hypothesis formation, IR always begins with facts that make no sense, facts that do not cohere, most commonly irregularities in an otherwise regular paradigm. The underlying affinity of IR with abductive reasoning is revealed right there: Both strive to re-establish coherence in the face of temporary incoherence.
Both abduction and IR presuppose that coherence must be or must have been there. In the case of a non-evolutionary science (chemistry), the presupposed coherence is of the synchronic system. In the case of evolutionary or diachronic sciences (biology, linguistics), one presupposes that coherence must have been there at some earlier evolutionary or diachronic stage.
The underlying assumptions that inspire IR are, much like hypothesis formation in science, profoundly universalist and unabashedly theoretical: that language as a communicative tool is in the main regular, or iconic. The notion of paradigmatic irregularity rests on the presupposition that paradigms tend, on the whole, to be — or at least start — regular. Much like the abductive reasoning practiced by the evolutionary biologist, the IR practitioner in linguistics takes it for granted that synchronic irregularities are merely the foot-prints of diachronic change from earlier regularities (Givón 1979, ch. 6).
