The phrase “D–N explanation” refers to the Deductive–Nomological model of scientific explanation, a framework in the philosophy of science developed by Carl Hempel and Paul Oppenheim in the mid‑20th century. It’s one of the most influential attempts to formalize what counts as a proper scientific explanation.
🌍 Definition
- Deductive–Nomological (D–N) Model: A scientific explanation is valid if the phenomenon to be explained (the explanandum) can be logically deduced from general laws (nomological statements) and specific initial conditions (explanans).
- Nomological: Refers to laws of nature (from Greek nomos, “law”).
- Deductive: The explanation must follow logically, like a proof.
🔑 Structure of a D–N Explanation
- Explanans (the explaining part)
- General law(s) of nature.
- Initial conditions or specific facts.
- Explanandum (the explained part)
- The event or phenomenon being explained.
- Logical Deduction
- The explanandum must follow deductively from the explanans.
📚 Example
- Phenomenon (Explanandum): A stone falls when dropped.
- Explanans:
- Law: Objects near Earth’s surface accelerate downward at ~9.8 m/s² (law of gravity).
- Condition: The stone is released from rest above the ground.
- Deduction: Therefore, the stone will fall.
🛠 Significance
- Philosophy of Science: Provided a rigorous model for scientific explanation.
- Strengths: Emphasizes logical structure and reliance on laws.
- Criticisms:
- Not all scientific explanations are deductive (e.g., statistical or probabilistic).
- Many sciences (biology, social sciences) rely on models, mechanisms, or probabilities rather than strict laws.
- Explains why something happens but not always how (mechanistic detail).
✨ Summary
The D–N explanation model defines scientific explanation as a logical deduction of phenomena from general laws and initial conditions. It was groundbreaking in formalizing explanation but has since been supplemented by probabilistic and mechanistic models.
