Scott Alexander made predictions in February 2018 for the next five years.

True: Scott Alexander published a set of predictions covering roughly the following five years (to about 2023) in February 2018, as shown by a dated Slate Star Codex post. Mostly true: such a predictions post exists but was dated in late January or early March 2018, or covers a slightly different horizon. Mostly false: he made predictions in February 2018, but only for one year rather than five, or made five-year predictions in a different year. False: no such predictions post exists from around February 2018.

Set before the research began.

1. E1 Predictions For 2018 Slate Star Codex · 6 February 2018 Own record

   “So here are a hundred more for 2018.”

2. E2 Grading My 2018 Predictions For 2023 Astral Codex Ten · 20 February 2023 Own record

   “To celebrate the fifth anniversary of my old blog, in 2018, I made some predictions about what the next five years would be like.”

E2 is a later post by the subject grading his '2018 Predictions For 2023'. It says that in 2018, to mark his blog's fifth anniversary, he made predictions about the next five years, so a five-year prediction set from 2018 existed. E2 does not give the month, and none of the evidence shows that post's date. E1 is a Slate Star Codex post dated 2018-02-06, but it covers predictions 'for 2018', a single year. Both sources come from the subject's own blogs, and the five-year predictions are not shown to date from February 2018.