X being a surprisingly simple counterargument. Not a new one, necessarily, just one that the text either fails to address or quietly dismisses without actually refuting it.

An annoying amount of philosophy is guys sitting in armchairs going "but what if contradictory things can be true? Didn't think of that, didja?"

EDIT:

For example:

Swampman, original formulation:

"it can't recognize anything, because it never cognized anything in the first place."

(Based on his glass marble thought experiment, Davidson defines "recognize" causally; that is, whatever caused the idea of the marble is what he means by "the marble", even if it has changed shape or been replaced with a copy. A nonstandard but useful definition, which implies we can be mistaken about what we mean/recognize/etc.)

Swampman is, of course, essentially a Boltzmann brain; he was formed by chance into a form that happens to be conscious. But more than that, he has been formed into a copy of someone else. Now, if he was formed entirely by chance, then an observer should not consider his beliefs to be correct, any more than a random number generator can reliably predict the weather. In this sense the concept of "recognize" is working perfectly; the author is just being mean.

However, the reader of course knows that Swampman is causally connected to Davidson, via the author's fiat; thus our intuitions in this case are closer to a clone than a true Boltzmann brain. And if a character in the thought experiment were to notice that Swampman was a perfect copy (which seems reasonable) they would have sufficient evidence postulate the author. Or at least some other god-level power screwing with them. In this sense Swampman is causally connected to Davidson - who really did "cognize" his friends - and thus genuinely "recognizes" them."

And, of course, an unfortunate amount of philisophy magically disappears when you start playing taboo and otherwise avoiding arguments over definitions.

SECOND EDIT:

OK, I can't reply to comments here due to the karma toll. If anyone's interested, I could post the example on an open thread for criticism?

As I said, I can only comment on my general impression of the field. I'm not an expert - in anything - and I don't move in philosophy circles.

Worse still, because of my experiences with e.g. theology, I may be unusually biased towards criticising philosophers without properly engaging with them. "My experience of philosophy" is more valuable than a high-schooler's, but it's probably nothing special as experience-of-philosophy goes.

Nevertheless, as I said, in my experience of philosophy there are few philosophers at EY's level.

I think that's relevant, and hey, if someone with better evidence disagrees then all the more data for me. But the grandparent didn't provide evidence; it used underhanded tactics to deflect away from it instead.

John Conway ... is awesome and much higher-level than me, but I'm not sure how that relates to the above discussion. As you say, he's a mathematician; I'm not sure who Philosopher!John Conway would be, even if I had met them. Which I haven't.