Theory Building (cps-theory-building)

CPS rewards arguments that travel. A good CPS theory is a mechanism with scope conditions that generates observable implications a comparativist can test in more than one setting. Theory can be verbal-causal, formal/game-theoretic, or comparative-historical — but it must do more than label; it must predict what should differ across cases and when the mechanism turns off.

When to trigger

• Turning a comparative puzzle into a stated argument with implications
• A reviewer said the paper "lacks a theory," "is descriptive," or "the mechanism is a black box"
• Your finding has no portable claim — nothing another comparativist could import
• You need to specify scope conditions and the contrast with the rival from cps-literature-positioning

What a CPS argument must deliver

1. A named mechanism. State the causal process in one sentence: actor → incentive/constraint → behavior → outcome. Give it a portable name so it can be cited and carried.
2. Observable implications. List 2–4 predictions, including at least one that distinguishes your mechanism from the rival (not just "outcome happens").
3. Scope conditions. Say where the mechanism should hold and where it should fail. A theory that predicts everything predicts nothing; scope conditions make it comparative and falsifiable.
4. Comparative statics / variation. State how the outcome should change as the key cause varies across cases or over time — this is what the design (cps-research-design) will exploit.
5. Micro-foundations where the claim is macro. If the argument is about regimes or systems, name the actor-level behavior that must hold for the macro pattern to obtain.

Modes of theorizing in CPS

Mode	Strength	Watch out for
Verbal-causal	Accessible, flexible	vague mechanism, unfalsifiable scope
Formal / game-theoretic	Precise comparative statics	model-empirics gap; assumptions doing all the work
Comparative-historical	Process and sequence, path dependence	selection on the outcome; ad hoc periodization
Typological	Organizes variation	categories without a mechanism behind them

The portability test (CPS-specific)

Write one sentence: "In a different region/regime — say ___ — the same mechanism predicts ___." If you cannot, the argument is a local description, not a comparative theory. Then write the distinguishing implication: "If the rival account were right instead of mine, we would see ___; my mechanism predicts ___ instead."

Checklist

• Mechanism stated in one sentence, with a portable name
• 2–4 observable implications, at least one distinguishing the rival
• Scope conditions: where it holds and where it fails
• Comparative statics stated (how outcome moves with the cause)
• Micro-foundations supplied if the claim is macro-level
• Portability sentence written for a second setting

Anti-patterns

• A label masquerading as a mechanism ("institutions matter")
• No scope conditions — the theory "explains" every case, so it is unfalsifiable
• Formal model whose comparative statics are never tested, or a loose analogy to the empirics
• Comparative-historical narrative that selects on the outcome
• A finding with no portable claim — nothing another comparativist could carry to a new case

Output format

【Mechanism】one sentence: actor → incentive → behavior → outcome (+ portable name)
【Observable implications】incl. the one distinguishing the rival
【Scope conditions】holds where / fails where
【Comparative statics】how outcome moves with the cause
【Portability】a named second setting where it should also hold
【Next】cps-research-design

Supplementary resources

• ../../resources/exemplars/library.md — verified CPS papers with portable mechanisms
• ../../resources/worked-examples/01-introduction.md — argument stated early in CPS house style