regress

(noun) the reasoning involved when you assume the conclusion is true and reason backward to the evidence. Synonyms: reasoning backward.

(noun) returning to a former state. Synonyms: regression, reversion, retrogression, retroversion.

(verb) go back to a statistical means.

(verb) go back to a previous state. Synonyms: revert, return, retrovert, turn back. Example: "We reverted to the old rules."

(verb) get worse or fall back to a previous condition. Synonyms: retrograde, retrogress.

(verb) go back to bad behavior. Synonyms: relapse, lapse, recidivate, retrogress, fall back. Example: "Those who recidivate are often minor criminals."