In class we discussed a test for semantic ambiguity: if there is a natural language that translates some English word w using two different words, that is evidence for w's being semantically ambiguous. For example, 'bank' in English, when used to mean what 'financial institution' means, is translated into German as 'Bank'. And when that English string is used to mean the side of a river, it is translated as 'Ufer'.
I claimed that 'know' when used to mean knowledge of an individual is translated in German as 'kennen', and propositional uses of 'know' are translated as 'wissen', and this is perhaps some reason to think that it's an accident of English that both relations are expressed using 'knows'. This, in turn, may help explain our difficulties in characterizing knowing an individual in terms of propositional knowledge.
It turns out that the linguistic facts are a bit more complicated. In fact, one can accurately translate 'I know you' using 'wissen'. And one also translates 'I know who you are' using 'wissen'. But, surprisingly perhaps, 'I don't know you' only translates using 'kennen', and 'I don't know who you are' only translates using 'wissen'. (Recall Justin asked if knowing an individual is expressed in German in the same way that knowing-who is. The answer is 'no', but what I said was not entirely accurate. Thanks, Justin, for the question!)
As indicated below, a number of philosophers hold that know-how is a species of propositional knowledge, though, of course, it's controversial. In 'Know (How)' by Jason Stanley, linked below, Jason Stanley considers these sorts of cross-linguistic objections to the view that know-how is propositional. He points out that German may not be a good test case for know-how, since the grammar of German prevents know-how claims from taking infinitives as complements. What that means is this: In English, know-how claims typically have this sort of form: S knows how to BLAH. A phrase of the form /to BLAH/ is an infinitive. So since the German grammar is quite different from English in this case, it's probably not a good guide to figuring out whether know-how and propositional knowledge are really different knowledge-relations in English.
Interestingly, some languages (Cantonese and Russian) use different expressions for know-how than they do for propositional knowledge. And as many of you may know, French constructions allow infinitive complements, but they differ significantly in surface structure from English know-how claims. Stanley considers whether these count against his view that know-how is a species of propositional knowledge in sections 6-8. Section 8 in particular focuses on the Cantonese-and-Russian objection. (The funny symbol he uses but does not explain is called 'lambda'. It works a bit like variable-binding expressions from quantified logic (quantifiers). You can get a hang of how it works by looking at the first few slides from Jeff Pelletier here
. It's not super important to the discussion though.)