The Scientific Image

Citation: Van Fraassen, B. C. (1980) The Scientific Image. Oxford University Press. (RSS)
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Download: http://isites.harvard.edu/fs/docs/icb.topic1470783.files/van%20Fraassen Scientific%20Image.pdf
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Summary

This is a brief summary of chapter 5 from this volume.

Some of the most problematic features of explanation, namely asymmetries and rejections, can be resolved by using van Frassen's three-part approach to answering why-questions. This approach uses the relationships between three factors, the theory, the fact, and the context of the question. The goal is to create relationships between the facts and the theory that will provide sound explanations independent of whether the evidence for that relationship exists in the real world. An excellent example of this is the explanation for the length of giraffe necks. Evolutionary theory proposes that the long neck is a result of evolutionary pressure in which a long neck is adaptive for survival. Although there is no evidence of food shortages that would select for that phenotypes, the facts and the theory provide sound explanations.

In order to be successful, a theory of explanation needs to accommodate and account for rejections and asymmetries. Rejections consist of cases in which sufficient conditions don't produce the same result in all situations. The paresis example in this chapter is a classic case, in which syphilis is a required condition for the development of paresis, but not all patients who suffer from syphilis will develop paresis. Asymmetries present in an explanation in the instance that conditions do not equally explain each other (asymmetric direction of the causal process).

The causal relationship and causal process are also important for how van Frassen conceptualizes scientific explanation. Causality supplies the "story" behind the explanation, for example, why the Tasmanian devil is endangered, or why Native Americans live on reservations. Causality for van Frassen must be contextualized. The answer to the question "Why is the porch light on", for example, as many potential answers depending on the context in which the question is asked.

Explanatory theories, then, in the pragmatist fashion, can be described in these general terms: 1) Events are enmeshed in a net of causal relations (2) What science describes is that causal net (3) Explanation of why an event happens consists (typically) in an exhibition of salient factors in the part of the causal net formed by lines leading up to that event (4) Those salient factors mentioned in an explanation constitute (what are ordinarily called) the cause(s) of that event. (1980:124)