The challenge of unawareness for impartial altruist action guidance

The core posts of this sequence are the posts numbered 1-4 in the titles, which introduce the problem of unawareness and its significant implications for cause prioritization.

"Winning isn't enough" and "Should you go with your best guess?" are background. The essential content from those posts is summarized in the core sequence, but I strongly recommend reading the background posts in full beforehand.