Exclusions, Explanations, and Exceptions: On the Causal and Lawlike Status of the Competitive Exclusion Principle

Abstract

The lawlike and explanatory status of ecologists' Competitive Exclusion Principle (CEP) is a debated topic. It has been argued that the CEP is a ceteris paribus law, a non-lawlike regularity riddled with exceptions, a tautology, a causal regularity, and so on. We argue that the CEP is an empirically respectful and testable strict law that is not riddled with genuine exceptions. Moreover, we argue that the CEP is not a causal explanans in explanations, because it is a coexistence law, not a causal law. Rather than being an explanans, the CEP acts as a contrastive principle sharpening causal explanations. These results contrast with previous analyses of the CEP by Eliot (2011) andWeber (1999), which are also discussed. As a more general conclusion, we suggest that accounts of causal explanation in biology have neglected some of the roles that non-causal laws play in restricting, sharpening, and facilitating causal explanations.

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