Second Order Effect

Second-order thinking looks past the immediate, obvious result of a decision to the effects that result triggers in turn.

The idea

First-order thinking stops at the direct, immediate consequence of an action. Second-order thinking asks “and then what?” It traces how that consequence changes incentives, behavior, or conditions further down the line. Many decisions that look good at the first level, such as a quick fix or a well-intentioned subsidy, turn out badly once their downstream effects are followed through.

When to use it

• Evaluating policies, incentives, or rules that change how people behave once in place
• Assessing an appealing “obvious” decision before committing to it
• Comparing options where the immediate payoff differs from the long-run outcome

How to apply it

1. State the direct, first-order effect of the decision.
2. Ask what that effect changes. Look at behavior, incentives, resources, and relationships.
3. Trace at least one more step. Ask what those changes cause next.
4. Weigh the second-order effects against the first-order appeal before deciding.

Watch out for

• Chains of consequences can be traced indefinitely; stop once further steps become too speculative to be useful.
• Overcorrecting by rejecting every option with a good first-order effect out of fear of hidden downsides.
• Confusing plausible-sounding second-order stories with actually likely ones.

Related models

• Third Order Effect. Extending the same reasoning one step further.
• Probabilistic Thinking. Weighing how likely each downstream effect actually is.
• Decision Making on Short, Medium, and Long Term. A related way of separating immediate from later consequences.

Sources

Howard Marks, The Most Important Thing: Uncommon Sense for the Thoughtful Investor (on first-level versus second-level thinking); Dietrich Dörner, The Logic of Failure (on the side effects and delayed consequences of intervening in complex systems).