Mechanisms versus Difference-Making

1. Mechanisms versus Difference-Making Examples from genetics and molecular biology Gry Oftedal 2009 University of Oslo

2. Goal • Use scientific practice to shed some alternative light on the philosophical causation debate • Suggestions: • Difference-making and counterfactual analyses mainly consider an epistemological notion of causation, while production/mechanisms/physical connection views mainly consider an ontological notion of causation. • Therefore, these different analyses need not be in direct competition, as they may consider different levels of causal information

3. Two causal assumptions in genetics and molecular biology • A cause makes a difference to the effect • There is a causal mechanism that links cause and effect • Mechanism: a continuous and dynamic chain or network of interactions between objects, sometimes on different levels, connecting the proposed cause and the relevant effect.

4. Two lines of philosophical inquiry • Difference-making and counterfactual analysis • Production/mechanism/physical connection analysis

5. Difference-making and epistemology • Experiment: If the introduced variation or difference in the proposed cause-variable is correlated with a variation or difference in the effect-variable, this is seen as a strong indication of causation. • Example: If you did not take this vitamin, you would not have caught that cold • Crucial observation: Difference-making approaches in science and in philosophy are about identifying/picking out causes of a certain effect • Difference-making and counterfactual analysis = our access to causation

6. Mill’s Method of Difference: • “If an instance in which the phenomenon under investigation occurs, and an instance in which it does not occur have every circumstance in common save one, that one occurring only in the former; the circumstance in which alone the two instances differ, is the effect, or the cause, or an indispensable part of the cause, of the phenomenon” (Mill 1974 [1843], 391).

7. Mechanisms and ontology • Next step in a biological investigation: finding the mechanism that explains the link between cause and effect • Not captured in counterfactual terms: causation is a structural relation that underlies and supports causal dependencies • Mechanisms: a pursuit to capture this underlying structural relation

8. Lurking counterfactuals • Psillos (2004): “(t)there is a sense, (…), in which the counterfactual approach (a fortiori the dependence approach) is more basic than the mechanistic (a fortiori the productive) one in that a proper account of mechanisms depends on counterfactuals while counterfactuals need not be supported by (or depend on) mechanisms”.

9. Mackie (1980) • There are “three kinds of analysis: factual, conceptual and epistemic. It is one thing to ask what causation is ‘in the objects’, as a feature of a world that is wholly objective and independent of our thoughts, another to ask what concepts of causation we have, and yet another to ask what causation is in the objects as far as we know it how we know what we do about it”.

10. Counterfactual dependence and production • Ned Hall: Two concepts or two kinds of causation: counterfactual dependence and production • Example: rainfall in April as a cause of a fire in June • The rainfall is a producer of structural change/change in physical and biological interactions connecting the rainfall and the fire, and thereby a productive cause of it.

11. Concluding remarks • There is an asymmetry between causal analyses in terms of counterfactual dependence and causal analyses in terms of mechanisms; the first mainly considers access to causes, how we pick out causes, the second mainly considers explanation of causal links and causal structure • Both these levels of investigation and analysis are indispensible and build on each other in biological research