Lindy Effect

Overview

For non-perishable items — ideas, books, technologies, institutions, practices — life expectancy is proportional to current age. The longer something has survived competitive elimination, the longer its expected remaining life. Math: if survival follows a Pareto distribution with α ≈ 1, expected remaining life ≈ current age. Not nostalgia — statistical inference from a track record of passing elimination tests.

Composes with antifragile (Lindy-survival is the signature of antifragility), survivorship-bias (paired warning), first-principles (Lindy says that; first-principles says why), switching-costs, and chestertons-fence.

When to Use

• Choosing a foundational technology / library / framework with high switching cost
• Evaluating a long-established practice or institution someone is proposing to discard
• Assessing a new methodology being marketed as "modern" or "evidence-based"
• Allocating reading time across old vs. new books
• Designing institutional partnerships with multi-decade horizons
• Deciding which layers of an AI stack to build on time-tested foundations (SQL, Unix, TCP/IP) vs. fast-churning AI frameworks amid the AI adoption hype
• Someone says "this has stood the test of time," "we should modernize," "this time is different"

Not when: item is perishable or has a deterministic life cycle; elimination forces are absent (old institution survives only via regulatory protection); conditions have genuinely changed enough to invalidate survival evidence; decision time-horizon is too short for long-run durability to matter.