A Morton’s Fork is a specious piece of reasoning in which contradictory arguments lead to the same (unpleasant) conclusion. It is said to originate with the collecting of taxes by John Morton, Archbishop of Canterbury in the late 15th century, who held that a man living modestly must be saving money and could therefore afford taxes, whereas if he was living extravagantly then he was obviously rich and could still afford them.
Elected officers (members of parliament and councillors) sometimes may have recourse to a variant on Morton’s Fork when dealing with unhelpful unelected officers, or civil servants. This variant asserts that an unelected officer’s non-compliance with the directive of their elected officer must be due to one of two equally unacceptable causes: either the civil servant is lazy or incompetent, or the civil servant is acting willfully or maliciously against the instructions given by his or her elected officer.
An example of Morton’s Fork occurs in the Poirot novel Death in the Clouds, in which Poirot sets a trap for the murderer by asking him to dress in disguise as a blackmailer. When the suspect does so – with a hapless lack of skill – Poirot reasons this was because the murderer was trying to hide the fact that he is actually highly adept at changing his appearance. Yet if the suspect had indeed proved his skill at disguise when asked (rather than dress up with “a false moustache that cries out to heaven, and those ridiculous eyebrows”), it would have alluded equally to his guilt.