What importance, if any, do infinitesimals still have to philosophers? It seems like many people are baffled by them. E.g., there's a slew of questions relating to Zeno on this site (not least by myself), and I hear that 0.999 is a common topic on discussion forums.
But it seems like trying to make sense of, for example, whether a point belongs to a line, makes no difference; nothing in mathematics hinges on it. So if the question about 'points' in mathematics is baffling, and after making certain standard assumptions, I find it so, I wondered whether infinitesimals raise problems for contemporary philosophers?
Does anything in philosophy hinge on infinitesimals, perhaps a phenomenology of mathematics? Or is asking about them outisde mathematics just an expression of bafflement?