The 5 Decade Rule

The Promise

Filter what is worth your attention by asking whether the underlying idea has survived fifty years of human use. The Lindy filter applied to ideas, not just media.

How It Works

• At intake, apply the filter. Favor sources where the core idea is at least fifty years old, even if the modern packaging is new.
• Find the idea grandparent. For every recent idea you encounter, locate the older idea it descends from. Read that instead, or in addition. The grandparent has more signal; the modern descendant is a translation.

In Practice

Most self-improvement content fails this filter. The majority of what circulates traces its core mechanics to ideas that predate it by decades or more. Applying the filter once at intake, and observing what survives, quickly reveals how much of what appears new is repackaging. The older source carries more signal.