Is it an impeachable offense?That is the question of the hour. On “Fox News Sunday,” Chris Wallace pressed it on Republican Congressman Will Hurd of Texas. It is a question every Republican supporter of President Trump should be prepared to answer. Democrats, by contrast, determined that the president was impeachable before he ever darkened the Oval Office door; it’s not worth asking them since their answer preexisted any real or imagined occasion for posing the question.It is, of course, the question that must be asked. That does not make it a fair question. It is unfair because it assumes a fact that is not in evidence, namely: that we have a working definition of an impeachable offense on which there is agreement – or at least something close to consensus. We don’t.REPORTER’S NOTEBOOK: THE ‘IMPEACHMENT RESOLUTION,’ AND DEMS’ FIGHT OVER ITS MEANINGIn fact, even that explanation of the problem is misleading. To have a “working definition” in this context implies that we are dealing with a legal reality – as if the question were, Is it a contract? Or, Is it a homicide? A contract or a homicide is a legal designation with a settled definition applicable in all circumstances.