A cabbie once said to a friend of mine something along these lines: “I’ve been married a few times, and when you’re trying to figure out whether you love someone or not, what you have to do is find all the most terrible things about that person. And then ask yourself if you can live with those things for the rest of your life.”
I’ve always been intrigued by the black swan problem introduced to me by Taleb who references much of Poincare’s work. The idea is that we can never really know if something is true no matter how much positive evidence we have. I can see a million white swans… but seeing this massive amount of white swans doesn’t necessarily make me sure that there are no black swans out there. However, just a single instance of negative evidence (in this case, a black swan) will nullify my hypothesis that there are only whites swans in existence.
And the similarities with love are striking. A lover can find someone, and run through all the million things he or she loves about that person… all well and good. But all that positive evidence of love will be nullified by just a single instance of negative evidence, like if the beloved is an ax-murder.
And so the cabbie seems right, even in an epistemological sense.