Invasion ecology addresses the spread of species outside of their native ranges. A central aim of this field is to find mechanistic explanations for why species are able to establish and spread in an area in which they did not evolve. Usually it remains unclear, however, what exactly is meant by ‘mechanistic explanation’ or ‘mechanism’. The paper argues that the field can benefit from the philosophical discussion of what a mechanism is. Based on conceptions of mechanisms as processes in concrete (...) systems, causal mechanisms can be defined as one type of mechanism, representing recurring networks of causal relationships. With the example of a well-known hypothesized mechanism in invasion ecology, namely enemy release, the paper demonstrates how such causal mechanisms can be depicted as causal network diagrams. This approach could facilitate the development of step-by-step explanations, enhance clear argumentation and allow for more precise linkage of empirical tests to theory. Challenges to assessing the empirical relevance of hypothesized mechanisms are discussed, and suggestions are made concerning how the proposed approach could help in overcoming some of them. (shrink)

Some theorists of normative explanation argue that we can make sense of debates between first-order moral theories such as consequentialism and its rivals only if we understand their explanations of why the right acts are right and the wrong acts are wrong as generative (e.g. grounding) explanations. Others argue that the standard form of normative explanation is, instead, some kind of unification. Neither sort of explanatory monism can account for all the explanations of particular moral facts that moral theorists seek (...) to state and defend. This paper argues that we can do better if we accept normative explanatory pluralism, the view that at least some particular explananda in normative inquiry have more than one type of correct complete explanation. Such pluralism is supported by what goes on in actual moral inquiry, parallels an independently plausible form of pluralism about scientific explanation, and can offer principled responses to central objections. (shrink)