---
title: Mechanisms in Science
type: concept
tags: [philosophy-of-science, causation, mechanism, explanation, reductionism]
sources: ["[[sources/2023-anjum-rocca-phi403-causation-in-science]]", "[[sources/2023-anjum-rocca-phi403-lecture-12-explanatory-power-of-mechanisms]]", "[[sources/2023-anjum-rocca-phi403-lecture-13-digging-deeper]]"]
created: 2026-04-20
updated: 2026-04-20
---

# Mechanisms in Science

A **mechanism** is an account of *how* a cause brings about its effect — the productive process that underlies an observed correlation. Mechanistic reasoning contrasts with, and complements, statistical / regularity-based reasoning.

## Two trends in science
- **Quantitative** — large-scale studies, statistics, what-and-how-often.
- **Qualitative / mechanistic** — how and why. Theory construction, process tracing.

Mechanisms hold more **explanatory power** than regularities: "married men live longer" is a statistical fact but does not license intervention without a mechanism (stress, diet, loneliness do the causal work, not marriage itself) ([[sources/2023-anjum-rocca-phi403-lecture-12-explanatory-power-of-mechanisms]]).

## The Russo-Williamson thesis
For a causal claim, seek **both** statistical evidence *and* mechanistic evidence. The course notes the **Semmelweis case** (hand-washing preventing puerperal fever) as a cautionary tale — his statistical evidence was disregarded because no mechanism of disease transmission was known.

## Mechanisms of stability
Not all causation produces change. **Equilibrium** (Moon's orbit) and **homeostasis** (body temperature, blood-oxygen levels) are instances of causation producing *stability*. Many theories of causation — those that require events or difference-making — mis-handle these cases.

## Reductionism, emergence, holism ([[sources/2023-anjum-rocca-phi403-lecture-13-digging-deeper]])
- **Reductionism** — all higher-level phenomena should be explained by lower-level mechanisms. Causation only travels bottom-up or within a level.
- **Emergence** — new properties/laws appear at higher levels; allows top-down causation. *Weak emergence*: epistemic; *strong emergence*: ontological.
- **Holism** — only wholes are causally powerful; parts gain their causal role from context.
- **Demergence** (Anjum & Mumford 2017) — higher-level processes produce new properties at the lower level (stress → physiological change; education → better diet).

## Relevance to process science
Process mining's classical descriptive/predictive outputs are regularity-like; [[concepts/causal-process-discovery|causal process discovery]] and [[sources/2025-fournier-agentic-ai-process-observability|agent process observability]] move toward mechanism-like representations, where the *functional* (not merely temporal) dependencies between activities are explicit. The distinction here mirrors the mechanism-vs-statistics debate.

## Related
[[concepts/causation]] · [[concepts/dispositionalism]] · [[concepts/regularity-theory-of-causation]] · [[concepts/evidence-hierarchy]] · [[concepts/causal-process-discovery]]