Online research in philosophy

Explanatory pluralism is the view that the best form and level of explanation depends on the kind of question one seeks to answer by the explanation, and that in order to answer all questions in the best way possible, we need more than one form and level of explanation. In the first part of this article, we argue that explanatory pluralism holds for the medical sciences, at least in theory. However, in the second part of the article we show that medical research and practice is actually not fully and truly explanatory pluralist yet. Although the literature demonstrates a slowly growing interest in non-reductive explanations in medicine, the dominant approach in medicine is still methodologically reductionist. This implies that non-reductive explanations often do not get the attention they deserve. We argue that the field of medicine could benefit greatly by reconsidering its reductive tendencies and becoming fully and truly explanatory pluralist. Nonetheless, trying to achieve the right balance in the search for and application of reductive and non-reductive explanations will in any case be a difficult exercise.

Our aim in this paper is to evaluate Frank Jackson and Philip Pettit’s ‘program explanation’ framework as an account of the autonomy of the special sciences. We argue that this framework can only explain the autonomy of a limited range of special science explanations. The reason for this limitation is that the framework overlooks a distinction between two kinds of properties, which we refer to as ‘higher-level’ and ‘higher-order’ properties. The program explanation framework can account for the autonomy of special science explanations that appeal to higher-level properties but it does not account for the autonomy of most of those explanations that appeal to higher-order properties.

The main claim in this paper is that because organisms have teleological constitutions, the reduction of biology to physical science is not possible. It is argued that the teleology of organisms is intrinsic and not merely projected onto them. Many organic phenomena are end-oriented and reference to ends is necessary for explaining them. Accounts in terms of functions or goals are appropriate to organic parts and processes. siis is because ends as systemic requirements for survival and health have explanatory significance with respect to the processes that contribute to and constitute them. Reductionism cannot accommodate this sort of higher-level to lower-level explanation and so cannot account for why lower-level phenomena are as they are. Reductionism, it is claimed, is ultimately descriptive and not explanatory because it cannot regard teleological requirements as themselves basic. In seeking to explain them away it forfeits explanatory power.

Some scientists and philosophers have claimed that there is a converse to multiple realizability. While a given higher-level property can be realized by different lower-level properties (multiple realizability), a given lower-level property can in turn serve to realize different higher-level properties (this converse I dubbed the unfortunately obscure "constructival plasticity" to emphasize the constructive metaphysics involved when realizing properties generate realized properties in the stated way). I begin by defining multiple realizabilty in a formal way, then turn to the relation in question. By my analysis, for the converse claim to be true, a lower-level property G1 that realizes a higher-level F must be taken in conjunction with some other base condition G2 so that a difference in G2 allows G1 to determine some other higher-level property E but not F (otherwise there would be violations of supervenience). The realization law thus has the form: (G1 & G2) => F. As such, the base property G1 is insufficient by itself to produce F. It is an insufficient but necessary part of a sufficient condition. I also point out that this makes the realization base property an INUS condition, if combined with multiple realizability. Specifically, if F is multiply realized by properties other than the pair G1 and G2, then G1 is an insufficient but necessary part of an unnecessary but sufficient condition.

Until recently, the notions of function and multiple realization were supposed to save the autonomy of psychological explanations. Furthermore, the concept of supervenience presumably allows both dependence of mind on brain and non-reducibility of mind to brain, reconciling materialism with an independent explanatory role for mental and functional concepts and explanations. Eliminativism is often seen as the main or only alternative to such autonomy. It gladly accepts abandoning or thoroughly reconstructing the psychological level, and considers reduction if successful as equivalent with elimination. In comparison with the philosophy of mind, the philosophy of biology has developed more subtle and complex ideas about functions, laws, and reductive explanation than the stark dichotomy of autonomy or elimination. It has been argued that biology is a patchwork of local laws, each with different explanatory interests and more or less limited scope. This points to a pluralistic, domain-specific and multi-level view of explanations in biology. Explanatory pluralism has been proposed as an alternative to eliminativism on the one hand and methodological dualism on the other hand. It holds that theories at different levels of description, like psychology and neuroscience, can co-evolve, and mutually influence each other, without the higher-level theory being replaced by, or reduced to, the lower-level one. Such ideas seem to tally with the pluralistic character of biological explanation. In biological psychology, explanatory pluralism would lead us to expect many local and non-reductive interactions between biological, neurophysiological, psychological and evolutionary explanations of mind and behavior. This idea is illustrated by an example from behavioral genetics, where genetics, physiology and psychology constitute distinct but interrelated levels of explanation. Accounting for such a complex patchwork of related explanations seems to require a more sophisticated and precise way of looking at levels than the existing ideas on (reductive and non-reductive) explanation in the philosophy of mind.

The history of the natural sciences repeatedly shows that the unification of a higher level theory with a lower level theory by reduction does not eliminate the need for the higher level theory nor preclude its further development, leading to changes in the understanding of the lower level. The radical neuron doctrine proposes that the future science of psychology or linguistics will derive principally from the evolution of understanding at the neural level and not from current theories based on the observation of behavior. It is far more likely that the two bodies of theory will coevolve in semiautonomous fashion.

Mechanisms in a theory are defined here as bits of theory about entities at a different level (e.g., individuals) than the main entities being theorized about (e.g., groups), which serve to make the higher-level theory more supple, more accurate, or more general. The criterion for whether it is worthwhile to theorize at lower levels is whether it makes the theory at the higher levels better, not whether lower-level theorizing is philosophically necessary. The higher-level theory can be made better by mechanisms known to be inadequate in the discipline dealing with the lower level. Conditions for the usefulness of lower-level theorizing are proposed, with many examples from various social and physical sciences.

The aim of this paper is to define a notion of supervenience which can adequately describe the systematic dependence of extrinsic as well as of intrinsic higher-level properties on base-level features. We argue that none of the standard notions of supervenience—the concepts of weak, strong and global supervenience—fulfil this function. The concept of regional supervenience, which is purported to improve on the standard conceptions, turns out to be problematic as well. As a new approach, we develop the notion of property-dependent supervenience. This notion is founded on a criterion of relevance adapting the supervenience base to the considered higher-level properties in a specific way, such that only features which are relevant to the instantiation of the higher-level properties under consideration are taken into account.

I compare two competing positions regarding relations between sciences: reductionism and explanatory pluralism. I argue that reductionism is not warranted by evidence from scientific practice, but on the other hand, it is important to emphasize certain fundamental differences between generalizations and explanations of different levels. To show this, I take up Woodward’s notion of invariance, arguing that lower-level generalizations generally have a higher degree of invariance under interventions than higher-level generalizations. Since degree of invariance tracks degree of explanatory depth, lower-level explanations are in this sense better than higher-level ones.

A common argument against explanatory reductionism is that higher‐level explanations are sometimes or always preferable because they are more general than reductive explanations. Here I challenge two basic assumptions that are needed for that argument to succeed. It cannot be assumed that higher‐level explanations are more general than their lower‐level alternatives or that higher‐level explanations are general in the right way to be explanatory. I suggest a novel form of pluralism regarding levels of explanation, according to which explanations at different levels are preferable in different circumstances because they offer different types of generality, which are appropriate in different circumstances of explanation. *Received July 2009; revised September 2009. †To contact the author, please write to: Department of Philosophy, Oklahoma State University, 246 Murray Hall, Stillwater, OK 74078; e‐mail: angela.potochnik@okstate.edu.