 Undeniably there is a real phenomenon here, but perhaps it belongs to pragmatics rather than semantics. If I say ‘I want a sloop’, someone who offers to buy me any sloop floating in the harbor could reasonably complain ‘You should have said that’ if I decline the offer on the grounds that none of those sloops meets my unstated requirement of having a hull riddled with holes. But my aspirational benefactor’s complaint might be justified because normality is a default implicature or presupposition that a co-operative speaker is under some obligation to let her audience know isn’t in force, when it isn’t. It is still literally true, on this view, that you want a sloop, despite the idiosyncrasy of the details of your desire. However, this is far from the end of the story. Those with doubts about weakening will find the discussion in (Sainsbury 2018, 129–133) congenial.