Ryan Collison

Before money changes hands, trust does. The invisible institutions behind every transaction — contracts, norms, reputation systems — are the real infrastructure of economic life, and they're surprisingly fragile.

Not everything spreads the same way. A rumor travels differently than a habit, which travels differently than a political identity. Network science has mapped these distinct contagion mechanisms — and the findings change how you'd design anything meant to propagate.

Epidemiologists use R0 to predict whether a pathogen will burn out or explode through a population. Apply the same framework to ideas and beliefs, and a disturbing picture emerges: misinformation often has a higher R0 than truth, for structural reasons that have nothing to do with stupidity.

Random networks and perfect lattices are both easy to analyze but rare in nature. Real social, biological, and technological networks cluster locally but stay globally connected — a structure with profound consequences for how quickly anything spreads through them.

You're not irrational when you follow the crowd. You're doing Bayesian inference badly. Information cascades show how rational individuals produce collectively catastrophic beliefs.

You don't catch sadness or joy consciously. You catch it through micro-expressions, vocal tone, and — as a now-infamous Facebook study showed — through algorithmically curated content. Emotional contagion is a measurable network phenomenon.