Sentence:  The significance of such a step is that it is not morphologically triggered: it is a step of <WSD>abduction</WSD>, and what is required here is a meta-level process of reasoning. 
Meaning of the word marked with <WSD> tags:  A syllogism or form of argument in which the major premise is evident, but the minor is only probable. (Late 17th century.)<ref name=SOED/>