One learned thing, every day

A quiet place to publish small ideas before they disappear.

Share one useful fact, mental model, diagram, paper note, or field observation each day.

Second-order effects are the consequences after the consequence

A decision can solve the immediate problem while creating new incentives, reactions, or costs later.

Today's takeaway

Before choosing an action, ask what will happen next because of the first result.

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Knowledge archive

Past notes

Cognitive Science · May 18, 2026

Second-order effects are the consequences after the consequence

A decision can solve the immediate problem while creating new incentives, reactions, or costs later.

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Cognitive Science · May 17, 2026

Survivorship bias hides the failures we do not see

When we study only the examples that made it through a process, we can mistake survival for the full story.

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Mathematics · May 16, 2026

Compound interest rewards consistency over intensity

Small gains can become large when they are repeatedly reinvested over time.

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Philosophy · May 15, 2026

The map is not the territory

A model, label, or diagram can help us understand reality, but it is always a simplification of the thing itself.

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Social Science · May 14, 2026

The rat race is a feedback loop between lifestyle and income

The rat race happens when higher income leads to higher spending, which then makes more income feel necessary.

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Biology · May 13, 2026

Homeostasis keeps living systems within workable limits

Living systems survive by regulating internal conditions even when the outside environment changes.

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Social Science · May 12, 2026

Marginal utility explains why the next unit matters most

The value of one more unit of something depends on how much of it you already have and what need it satisfies next.

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Mathematics · May 11, 2026

The pigeonhole principle turns counting into certainty

If more objects are placed into fewer boxes, at least one box must contain more than one object.

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Psychology · May 10, 2026

The forgetting curve is steepest right after learning

Reviewing a new idea soon after first contact gives memory something to hold onto before the first big drop.

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Publishing rhythm

A simple structure for daily sharing

01

One idea

Keep each post focused enough that we can remember it after a minute.

02

Why it matters

Connect the fact to a decision, habit, question, or way of seeing the world.

03

Source trail

Meditate learning without turning the daily note into a full essay.