e/Argument from setting a precedent

Information
has gloss	eng: Argument from precedent is a common fallacy in discussion, for example on committees or in meetings. It consists in saying that to act correctly in circumstances X would be inadvisable, in case others consider that this would set a precedent for acting in circumstances Y, where (it is argued) X and Y are superficially similar but (on close examination) are radically different. The Microcosmographia Academica, published in 1908, cited this as one of the reasons why "nothing should ever be done for the first time".
lexicalization	eng: Argument from setting a precedent
instance of	(noun) a misconception resulting from incorrect reasoning false belief, fallacy