Pragmatist philosopher Charles Sanders Peirce drew a sharp distinction between two kinds of beliefs: those that merely feel settled and those that actually are settled — meaning they survive contact with reality when you act on them. He called the sensation of settled belief 'the fixation of belief,' and he was ruthless about the difference between comfort and genuine conviction. Product managers almost always have beliefs in the first category masquerading as the second. The conviction that users want simplicity, that enterprise buyers prioritize security, that the core workflow is intuitive — these feel resolved because no one has recently pushed on them, not because they've been tested. Peirce's uncomfortable prescription was that a belief only earns its settled status through a specific mechanism: repeated, uncomfortable exposure to cases that could falsify it. Not edge cases you already control for. Cases that could actually break the belief. The practical implication: somewhere in your product's reasoning right now, there's a 'we know this' that hasn't faced genuine pressure in over a year. That belief isn't settled. It's just old.

Name one belief your team treats as resolved — something nobody debates anymore. What was the last actual event that could have falsified it, and did you pay attention when it happened?

Drawing from American Pragmatism — Charles Sanders Peirce (The Fixation of Belief, 1877)