1. Causality, Mechanisms and Intervention by Donald Gillies, University College London

2. Contents 1. Introduction 2. Example of a Mechanistic View of Causation: Salmon and Dowe 3. Criticism of the Mechanistic View of Causation 4. Epistemological Advantages of the Search for Linking Mechanisms 5. Theoretical and Practical Advantages of the Search for Linking Mechanisms

3. Salmon's Dog Whistle Example Suppose, for example, that a person has a whistle and a dog. When the person blows the whistle, we hear nothing but in every case the dog comes. We learn inductively that blowing the whistle is a sufficient condition for the appearance of the dog. But we do not understand the relation between the cause and the effect unless we know that there is a sound wave that we cannot hear because the frequency is too high for humans but not too high for dogs. The dog comes because it hears the whistle of its master. The wave is the causal process that provides the connection. (Salmon, 1993, p. 22)

4. Causal Definition of Linking Mechanism C 1,C 2,...,C n is a mechanism linking A to B if A → C 1,C 1 → C 2,...,C n-1 → C n and C n → B, where A causes B is written A → B

5. The Need for Interventional Evidence Correlations can be established by observational evidence alone, but to establish a causal claim one needs at least some experimental (or interventional) evidence.

6. Linking Mechanism for Heart Attack Diet High in Animal Fats → High Levels of LDL in the Blood → Oxidation of LDL → Attack on Oxidised LDL by Macrophages → Formation of Foam Cells → Attraction of Monocytes → Further Macrophage Attacks & Formation of Foam Cells → Formation of Atherosclerotic Plaques → Increased Adhesion of Monocytes to Arterial Walls especially those with Plaques → Acceleration of Formation of Atherosclerotic Plaques → Heart Attack