Sentence:  But in the fallacy of false <WSD>dichotomy</WSD>, not only do the two alternatives fail to be jointly exhaustive, but they are not even likely. As a result, the disjunctive premise is false, or at least probably false. 
Meaning of the word marked with <WSD> tags:  The division of a class into two disjoint subclasses that are together comprehensive, as the division of "man" into "white" and "not white".