non sequitur

English Thesaurus

1. (logic) a conclusion that does not follow from the premises (noun.cognition)

hypernym	:	conclusion,
definition	:	an intuitive assumption (noun.cognition)

domain category	:	logic,
definition	:	the branch of philosophy that analyzes inference (noun.cognition)

2. a reply that has no relevance to what preceded it (noun.communication)

hypernym	:	reply, response,
definition	:	the speech act of continuing a conversational exchange (noun.communication)