Monstrumologist/Headscratchers

• So about that extremely Arbitrary Skepticism of Pellinore's-- other than one time-sensitive reason that doesn't pop up until way later (that being "If it's real, your girlfriend is super dead right now."), is there any actual reasoning behind this? At first, it could've possibly been written off as a sort of monstrumology in-joke, something to make you go "Wait, what?" when it's mentioned that vampires are obviously completely fictional, with no explanation as to why (and assumably there's some fancy science behind it that we're not being told about), but then it becomes a central element in the second book. I suppose it could be to show that when Pellinore Warthrop is Absolutely Sure about something, he will marry and grow old and die with it, but even that doesn't explain howabouts he come to be so Absolutely Sure in the first place. It would make sense if, at any point, he (or anyone at all) just straight up explained why ___ couldn't exist according to current scientific knowledge, but instead it's just "NOOOO! It doesn't, shut up!" It's also baffling that he doesn't get called on it more often and with more gusto. Instead of "Man, what you just said there don't make no sense, here's why: ___", we get Hamlet quotes. No one (as far as I can remember) ever stops him and says "Now, hold on just a minute there, let's break this down."