---
title: "PHI403 Lecture 08 — Have Your Cause and Beat It"
type: source
tags: [philosophy-of-science, intervention, interference, context-sensitivity, causal-expansion]
authors: [Anjum, Rani Lill; Rocca, Elena]
year: 2023
venue: "PHI403 Causation in Science, NMBU"
kind: handout
raw_path: "raw/Philosophy of Science/PHI302 08 Have Your Cause and Beat It.pdf"
created: 2026-04-20
updated: 2026-04-20
key_claims:
  - Interference and prevention are routine — the cause–effect link is fragile to context.
  - Two kinds of interference: subtractive (remove the cause) and additive (add a counteracting factor). Additive interference undermines the constant-conjunction view.
  - Antipathetic interference — clonidine and beta-blockers each reduce blood pressure separately but combined can increase it.
  - Causal expansion (add all conditions to the cause) fails: either X becomes too large to be practical, or it swallows the whole world (every effect having the same cause).
---

# PHI403 Lecture 08 — Have Your Cause and Beat It

On **interference**: the reason causes fail to produce their effects is that the world contains preventers and disturbers. The lecture distinguishes:

- **Subtractive interference** — remove a causal factor (quit smoking). Sometimes impossible (cannot remove the Sun).
- **Additive interference** — add a counteracting factor (air-conditioner). Critically, *you can "have your cause and beat it"* — A is genuinely present and causally active, yet B does not follow.
- **Antipathetic interference** — two causes in combination produce the opposite of their individual effects (clonidine + beta-blockers).

Additive interference is a direct **refutation of constant-conjunction causation**: A can cause B while also sometimes *not* being followed by B, purely because of an added interferer. The Humean response is **causal expansion**: include all the relevant conditions in the cause. But expansion either never ends (the cause swallows the world) or remains fragile (each new factor is itself subject to interference). Causal isolation and expansion do not *prove* "same cause, same effect" — they *assume* it.

This lecture is where the course's [[concepts/interventionist-theory-of-causation|interventionist]] commitments are most visible: interference is what makes *intervention* possible.

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