Within the last 20 years, the US has mounted amassive campaign against invasions bynon-indigenous species (NIS) such as zebramussels, kudzu, water hyacinths, and brown treesnakes. NIS have disrupted native ecosystemsand caused hundreds of billions of dollars ofannual damage. Many in the scientificcommunity say the problem of NIS is primarilypolitical and economic: getting governments toregulate powerful vested interests thatintroduce species through such vehicles asships' ballast water. This paper argues that,although politics and economics play a role,the problem is primarily one of scientificmethod. (...) Even if commercial interests werewilling to spend the necessary funds to controlNIS, and even if government were willing toregulate them, ecological theory is notadequate to provide clear direction for eithereffort. The paper argues there is nocomprehensive, predictive theory ofinvasibility, as part of a larger theory ofcommunity structure, that might guideecological decision making regarding NIS, andfor at least three reasons. (1) There is nofirm definition of NIS, native, exotic,and so on, and ecologists do not use the termsconsistently; as a result, biologists debatingvarious accounts of community structure andecological explanation often do not even makelogical contact with each other. (2) Thedominant theory used to understandinvasibility, island biogeography, has noprecise predictive power and is unable toclarify when NIS might promote biodiversity andwhen they might hinder it. (3) There are nofirm, empirical generalizations that revealwhen a colonizer or a NIS might be likely totake over a new environment, and when it mightnot succeed in doing so. As a result,scientists have only rough rules of thumb toshore up their arguments against NIS. Given theincompleteness of current ecological theory,the paper closes with several suggestions forways that study of NIS might enhanceunderstanding of basic commmunity structuresand vice versa. (shrink)

I present an attempt at an explication of the ecological theory of interspecific competition, including its explanatory role in community ecology and evolutionary biology. The account given is based on the idea that law-like statements play an important role in scientific theories of this kind. I suggest that the principle of competitive exclusion is such a law, and that it is evolutionarily invariant. The principle's empirical status is defended and implications for the ongoing debates on the existence of biological laws (...) are discussed. (shrink)

How are scientific explanations possible in ecology, given that there do not appear to be many—if any—ecological laws? To answer this question, I present and defend an account of scientific causal explanation in which ecological generalizations are explanatory if they are invariant rather than lawlike. An invariant generalization continues to hold or be valid under a special change—called an intervention—that changes the value of its variables. According to this account, causes are difference-makers that can be intervened upon to manipulate or (...) control their effects. I apply the account to ecological generalizations to show that invariance under interventions as a criterion of explanatory relevance provides interesting interpretations for the explanatory status of many ecological generalizations. Thus, I argue that there could be causal explanations in ecology by generalizations that are not, in a strict sense, laws. I also address the issue of mechanistic explanations in ecology by arguing that invariance and modularity constitute such explanations. (shrink)

This essay explores two strategies of inquiryin ecological science. Ecologists may regardthe sites they study either as contingentcollections of plants and animals, therelations of which are place-specific andidiosyncratic, or as structured systems andcommunites that are governed by general rules,forces, or principles. Ecologists who take thefirst approach rely on observation, induction,and experiment – a case-study or historicalmethod – to determine the causes of particularevents. Ecologists who take the secondapproach, seeking to explain by inferringevents from general patterns or principles,confront four conceptual obstacles (...) which thisessay describes. Theory in ecology must (1)define and classify the object it studies,e.g., the ecosystem, and thus determine theconditions under which it remains the ``same''system through time and change. Ecologistsmust (2) find ways to reject as well as tocreate mathematical models of the ecosystem,possibly by (3) identifying efficient causes ofecosystem organization or design. Finally,ecologists will (4) show ecological theory canhelp solve environmental problems both inpristine and in human-dominated systems. Afailure to solve – or even to address – theseobstacles suggests that theoretical ecology maybecome a formal science that studies themathematical consequences of assumptionswithout regard to the relation of theseassumptions to the world. (shrink)

Philosophers, policymakers, and scientists have long asserted that ecological science – and especially notions of homeostasis, balance, or stability – help to determine environmental values and to supply imperatives for environmental ethics and policy. We argue that this assertion is questionable. There are no well developed general ecological theories having predictive power, and fundamental ecological concepts, such as 'community' and 'stability', are used in inconsistent and ambiguous ways. As a consequence, the contribution of ecology to environmental ethics and values lies (...) more in the realm of natural history and case studies than in the realm of general theory. Moreover, although general ecological theory is unable to contribute to environmental values in the way many philosophers and policymakers have hoped, environmental values can and do contribute to ecological hypotheses and methods. Using examples related to preservation versus development, hunting versus animal rights, and controversies over pest control, we show that, because ecology is conceptually and theoretically underdetermined, environmental values often influence the practice of ecological science. (shrink)

Rolston (1988) argues that in order to act ethically in the environment, moral agents must assume that their actions are potentially harmful, and then strive to prove otherwise before implementing that action. In order to determine whether or not an action in the environment is harmful requires the tools of applied epistemology in order to act in accord with Rolston’s ethical prescription. This link between ethics and epistemology demands a closer look at the relationship between confirmation theory, particularly notions of (...) plausibility, in the philosophy of science and environmental ethics. Upon taking this look, I conclude that, at least logically, we are no better off assuming that actions are maximally risky (Rolston) than when we assume minimal risk. “Our vulnerability to error is greatest not from the things that we include in the model, but from the prophecies we leave out entirely.” Francis Bretherton “What is the main epistemic problem concerning science? I take it that it is the explication of how we compare and evaluate theories, as a basis either for theory acceptance or for practical action.” Bas van Fraassen “We face two kinds of ethical difficulties. One is where we know what ought to be done but not how to get the company to do it. The other is where we do not know what is right. We do not know the facts, or how to weigh the facts, especially statistical ones. We do not know the probabilities for development of future technologies. We do not know how to attach values to facts, or how to trade this good off against that one.” Holmes Rolston. (shrink)

This article examines how the authorization of scientific discourses in the US Endangered Species Act of 1973 has influenced the ways people make claims about culturally significant animals. In it, I focus on struggles over the management of two endangered fish species among a federally recognized Native American tribe, state resource managers, and other actors. I discuss how the requirements of the ESA, namely that decisions regarding the protection of endangered species must be made based “solely on the basis of (...) the best scientific…data available,” have pushed people to reframe their cultural claims about the environment as scientific claims in order to gain legal authority. I argue that these animals span the social worlds of indigenous hunters and fishers, regulators, and ecological scientists. As such, they offer the opportunity to interrogate the relationships among ways of knowing the environment. I suggest that strict divisions among “types” of knowledge as well as hard-and-fast bonds between groups and “their” knowledge become problematic. Instead, people assemble eclectic articulations of knowledge to make the most authoritative claim possible in a given context, contradicting the assumption that certain people know the world only, or primarily, in a particular way. (shrink)