---
title: "PHI403 Lecture 13 — Digging Deeper to Find the Real Causes"
type: source
tags: [philosophy-of-science, reductionism, holism, emergence, levels, demergence]
authors: [Anjum, Rani Lill; Rocca, Elena]
year: 2023
venue: "PHI403 Causation in Science, NMBU"
kind: handout
raw_path: "raw/Philosophy of Science/PHI302 13 Digging Deeper to Find the Real Causes.pdf"
created: 2026-04-20
updated: 2026-04-20
key_claims:
  - Reductionism holds that all higher-level phenomena should be explained by lower-level mechanisms; causation travels only bottom-up or within a level.
  - Ontological reductionism has limits: some phenomena are lost at lower levels; lower-level descriptions may give necessary but not sufficient conditions for higher-level causation.
  - Emergence (weak vs strong) allows higher-level properties to be irreducible and possibly top-down causal.
  - Holism: only wholes are causally powerful. Anjum & Mumford 2017's "demergence" — higher-level processes produce new properties at the lower level (stress → physiology).
---

# PHI403 Lecture 13 — Digging Deeper to Find the Real Causes

On **levels of explanation** and the direction of causation between them. Reductionism is the dominant scientific methodology: explain higher-level events (tiredness, depression, society) by lower-level ones (bacteria, chemistry, individuals, neurons).

Ontological reductionism faces two problems:

1. **Loss at lower levels** — art is not just colours and light waves; society is not just a collection of individuals; mind is not just neurons.
2. **Necessary but not sufficient** — "my arm needs molecules to move, but I can't move my arm by moving my molecules".

**Emergence**: new properties / laws appear at higher levels.
- *Weak emergence* — epistemic; prediction from the lower level is hard, but ontology is still bottom-up.
- *Strong emergence* — ontological; higher-level properties are genuinely new.

**Holism** — only wholes are causally powerful; parts' causal roles depend on context. Genes cause as parts of living cells; cells as parts of organisms; organisms in environments (Lewontin, *The Triple Helix*, 1998).

**Demergence** (Anjum & Mumford 2017) — higher-level processes produce new properties at a *lower* level: stress causing physiological changes, education causing better diet.

The net result is a picture where [[concepts/causation|causation]] travels up, down, and across levels — irreconcilable with strict reductionism but congenial to dispositionalism.

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