---
title: "PHI403 Lecture 05 — Same Cause, Same Effect?"
type: source
tags: [philosophy-of-science, causation, hume, exceptions, outliers, noise]
authors: [Anjum, Rani Lill; Rocca, Elena]
year: 2023
venue: "PHI403 Causation in Science, NMBU"
kind: handout
raw_path: "raw/Philosophy of Science/PHI302 05 Same Cause Same Effect.pdf"
created: 2026-04-20
updated: 2026-04-20
key_claims:
  - The "same cause, same effect" principle (Hume, Kutach, Norton) is a philosophical commitment, not an empirical finding.
  - Real causal connections almost always show exceptions — treated as outliers, noise, non-responders, or interferers.
  - These treatment strategies presuppose the principle rather than testing it; they save the Humean ontology by adjusting the data.
  - If same cause → same effect, then by contraposition different effects imply different causes — opening the door to causal expansion.
---

# PHI403 Lecture 05 — Same Cause, Same Effect?

Examines the philosophical commitment underlying the [[concepts/regularity-theory-of-causation|regularity theory]]: **robustness** and **repeatability** as necessary for a cause. Norton and Kutach call this the *folk theory of causation* — causes necessitate effects, determinism holds, the same cause gives the same effect.

In practice, life-science and social-science data rarely show perfect regularities. The course catalogues the **rescue strategies** scientists deploy:

- **Exceptions** — universal truths admit of albino ravens.
- **Outliers** — deviating data points are discarded as mistakes.
- **Noise / error** — smaller deviations fitted by the model's error term.
- **Non-responders** — patients who don't respond to treatment.
- **Interferers** — contextual factors that disturb the effect.

All of these are ways to save the principle "same cause, same effect" rather than giving it up. Hume's corollary — different effect ⇒ different cause — motivates [[sources/2023-anjum-rocca-phi403-lecture-08-have-your-cause-and-beat-it|causal expansion]].

## Connections
Back-link: [[sources/2023-anjum-rocca-phi403-causation-in-science]]. Concepts: [[concepts/regularity-theory-of-causation]] · [[concepts/dispositionalism]] · [[concepts/causation]].