The ambiguity theory of ‘knows’ is the view that ‘knows’ and its cognates have more than one propositional sense – i.e. more than one sense that can properly be used in ‘knows that’ etc. constructions. Given that most of us are ‘intuitive invariantists’ – i.e. most of us initially have the intuition that ‘knows’ is univocal – defenders of the ambiguity theory need to offer an explanation for the semantic blindness present if ‘knows’ is in fact ambiguous. This paper is an attempt to offer such an explanation. Section 1 contains a general argument for the ubiquity of semantic blindness for ambiguous words; the upshot being that semantic blindness for the ambiguity of ‘knows’ is thus unsurprising. Section 2 offers more specific arguments for why ‘knows’ is the type of ambiguous word that we’re very unlikely to quickly recognize is ambiguous.