Mental Models

A working library of thinking tools drawn from investing, systems science, biology and psychology — used to sanity-check theses, catch second-order effects, and avoid predictable mistakes in the research process.

Maths

Lindy Effect

Reference: Skin in the Game

For non-perishable things — ideas, books, institutions — future life expectancy is proportional to current age. The longer something has survived, the longer it's likely to keep surviving.

Biology

Gene Fitness

Reference: The Selfish Gene

A business can't be evaluated in isolation. Its fitness is contextual — it depends on the competitors and market dynamics around it, just as a gene's fitness depends on the gene pool it operates within.

Biology

Natural Selection

Reference: The Selfish Gene

Financial markets mirror biological selection: companies unable to adapt to a changing environment face extinction, regardless of past dominance.

System Science

Complex System

Reference: Complexity: The Emerging Science at the Edge of Order

A network of many interacting, interdependent parts whose collective behavior emerges from — but can't be reduced to — the sum of its individual components, making outcomes hard to predict.

System Science

System Thinking

Reference: Thinking in Systems

Looking beyond first-order effects to second-order consequences, tracing balancing and reinforcing feedback loops through a system rather than treating it as a straight line of cause and effect.

Psychology

Ulysses Contract

Reference: The Brain

A binding choice made while calm and clear-headed to restrict your own future options — precommitting so that a future, more irrational version of yourself can't act on temptation.

Business

Disruptive Innovation

Reference: The Innovator's Dilemma

A smaller company with far fewer resources can still dislodge an established incumbent by entering from below, on dimensions the incumbent is structurally unmotivated to defend.

Psychology

Inversion

Reference: Poor Charlie's Almanack

Solving a difficult problem backward — by asking how to reliably achieve the exact opposite of your desired outcome, then avoiding those actions.

Sociology

Minority Rule

Reference: Skin in the Game

Markets and societies are often governed not by the average preference of the majority, but by a small, inflexible minority with real skin in the game and zero tolerance for compromise.

Maths

Ensemble vs. Time Probability

Reference: Skin in the Game

Sequence matters. A multiplicative, fat-tailed risk that can wipe you out entirely is never comparable to a repeatable, predictable fluctuation — even if their average expected outcomes look similar.