One way to avoid the skeptic’s conclusion that, in reality, we know nothing, is to go down the route of saying that whether we have knowledge depends upon the context of one’s conversation. So, for instance, if we’re merely talking casually in the street about what time the bus leaves, the standards of justification necessary to say ‘I know the bus leave at 3pm’ are much lower than, say, what is needed to prove a man is guilty in a court of law. So the meaning of the word ‘know’ changes in accordance with the importance of being correct.
So the contextualist can say that what the skeptic does is to shift the standards, and by ‘shift’ we mean ‘lift them sky high’. They burst into a street-level conversation and enforce court-room levels of justification. And, therefore, insofar as they succeed in changing the context, they are right: we don’t know the issue in question. But that turns out to be perfectly consistent with saying that in our original context, we nevertheless knew what we claimed to.
An analogy may help here: imagine that you claimed this table I am working on is flat, but I respond by saying ‘ah, but if we observed it under a microscope wouldn’t we see an infinite number of tiny bumps? So it’s not flat after all’. Now, you have two options here: you can give in and say you were wrong after all. Or, surely more plausibly, you can insist that the table is flat. And why? Because the definition of flatness I presupposed what just not what you had in mind. All you meant by flat was ‘it looks smooth’.
Similarly, then, perhaps we can tell the following story about the Birther issue: we say, entirely legitimately, that we have seen Obama’s birth certificate and have no particular reason to doubt its authenticity, especially given what we know about birth certificates and what they normally prove. Hence, we know Obama was born in Hawaii.
The skeptic comes along and says no: you haven’t ruled out these wild conspiracies. But when we claimed we had knowledge, we never suggested we had ruled them out! We just ignored them as irrelevant.
Does this mean that infallibilism – the principle I mentioned which says knowledge requires ruling out every possibility – is rejected as false? It may seem to be, because we aren’t bothering to engage with the skeptic’s whacky ideas. But in fact, the contextualist can say that like the words ‘flat’ and ‘know’, the word ‘every’ also varies in meaning. If I say ‘every’ glass has wine in it, I need not mean every glass in the world. I probably just mean every glass at the party I’m attending. Similarly, ‘every’ can have its domain restricted so that we do, in a sense, rule out ‘every’ possibility. But that doesn’t mean we refute the skeptic’s conspiracy, just like we don’t look at the glasses that we don’t care about outside of the party in question.