The Copernican Principle

The Copernican principle says: don't assume a privileged position. We're not at a special time or place in the universe—or in a distribution. Applied to duration: if you have no other information, your current position in an process's lifespan is likely not near the very start or very end; a simple prior is that you're somewhere in the middle. So the expected remaining duration is on the order of the elapsed duration. It's a default when you lack better reference classes: avoid assuming "we're at the beginning" or "this will last forever." Used for order-of-magnitude estimates of longevity (projects, technologies, trends) when data is scarce.

When you have no strong prior on where you are in a timeline, use the Copernican default: you're not special, so remaining duration is plausibly on the order of elapsed duration. Update with reference classes (similar projects, technologies) when available. In strategy: avoid both "we're just getting started" and "this will last forever" without evidence; the principle nudges toward moderate expectations.

The Copernican principle: don't assume a privileged position. For duration, that implies remaining time on the order of elapsed time when no better reference exists. Use it for order-of-magnitude longevity estimates; refine with reference classes when available.