The art of thinking · Mental models as thinking tools
Second-order thinking
Also known as: Second-level thinking, Consequences of consequences, What is seen and what is not seen
As a thinking tool, second-order thinking means considering not only the immediate effect of a decision but the effects of that effect — how others react, what changes over time, and what is not seen at first.
- Thinking models
- Problem solving
- Strategy
In one sentence
Second-order thinking asks “and then what?”: the effects of the effects, how others react, and what changes over time.
Example
First-order: adding a warning to every step makes each step safer. Second-order: readers learn to skip warnings, so the one that matters is skipped too. The decision changes once the second effect is considered.
How it applies
- Bastiat’s seen and unseen: In his essay of 1850 Frédéric Bastiat contrasted the visible effect of an action with its unseen effects — his broken window creates work for the glazier, but the money is no longer spent elsewhere. The good economist, he wrote, takes both into account.
- Investment thinking: Howard Marks (The Most Important Thing, 2011) described “second-level thinking” as asking what others expect and what follows from that, not only whether something is good.
- Questions: And then what? Who reacts, and how? What happens over time, at scale, when everyone does it? What does this make less likely?
- Technical documentation: Many documentation decisions have second-order effects on reader behavior — more warnings, more cross-references, more variants in one document. Thinking one step further connects the page to the systems thinking view of the reader’s situation.
Second-order thinking vs. speculation
Second-order thinking traces plausible effects that can be checked — by observation, testing or feedback; it does not justify inventing remote scenarios. Its conclusions are hypotheses to test, like any other.
How to read this pool
Entries, context cards and transitional topics
The art of thinking explains ways of thinking — where a method comes from, what it asks of you and how it was adapted later. You meet four kinds of content here, each with its own job:
- Glossary entry
- Defines one concept or method of thinking: its origin, an example and how it relates to neighboring ideas. “X vs. Y” sections set two methods side by side.
- Context card of the art of thinking
- A short, self-contained answer to one question about a way of thinking — its lineage, its steps, its limits. These cards are listed on The art of thinking only.
- Transitional topicBridges both pools
- A context card that bridges both pools: it shows how a way of thinking was adapted into documentation, analysis or quality practice. It sits with the reference context cards and is marked as transitional wherever it appears.
- Reference entry or context card
- Belongs to the Glossary & Norms Space on regulation, norms and engineering. Entries here link to one only where a method is also an established tool of documentation or quality work, such as the five whys or a user’s mental model.