The puzzle: Reductionism says fundamental laws are at the bottom. But sometimes, throwing away microscopic details increases predictive power.

Example: A gas molecule's trajectory is chaotic and unpredictable. But the ideal gas law (PV=nRT) is highly deterministic. Macro-level causation is stronger than micro-level.

Why it matters: If higher-level descriptions have genuine causal power, emergence isn't just epistemological bookkeeping — it's ontologically real. The macro-scale can be "more real" than the micro-scale for certain questions.

Key question: Under what conditions does information loss through coarse-graining increase rather than decrease causal efficacy?