You come across this comment on a Yankees subreddit: “The Yankees would be winning if not for horrible Aaron Judge. He brings down the team! Worst Captain EVER!!” You try to engage this person, pointing out Judge’s positive demeanor, how well liked he is by his teammates, and his offensive and defensive prowess. At every turn they repeat essentially the same remark. Eventually, you realize this person is trolling you: they’re pretending to be a Yankees fan, engaging you in conversation as though they’re expressing sincerely-held beliefs, but in fact they just enjoy annoying other people and wasting their time.

As is well-known, some skeptics in philosophy have asked: “How can you know you’re not a brain in a vat being artificially stimulated through electrodes to experience as if you’re in a real world?”. Yet ‘brain in a vat skeptics’ of this sort are much like the Redditor troll. They are philosophy trolls. Serious metaphysicians who structure their theories around responding to the brain in a vat question are wasting their time, while simultaneously legitimating an unreasonable objection.