ABSTRACT
Evidence in the context of action
Grant Fisher
University College, London
In philosophy of science, particular emphasis is placed on expressing the confirmation relation as a logical relationship between statements. This has proved to be enormously productive, resulting in qualitative analyses of confirmation and the application of various interpretations of probability to the logic of induction. However, developments in confirmation theory have been conjoined by a number of puzzles and paradoxes that have had a strong impact in not only philosophy of science but also epistemology more broadly. In order to overcome these problems, and to capture the practices of evidence collection, interpretation, assessment, deployment and evidential reasoning in the natural sciences, an analysis is required in which confirmation is understood as consisting in more than the logical relationships between statements.
Admitting extra-logical “contextual factors” into the study of evidence in philosophy of science has prima facie plausibility. Some contributions to the study of scientific explanation have shifted from the idea that explanation is a matter of logical subsumption of explanadum by explanans; it depends on pragmatic and contextual factors relating to who requests an explanation, who provides it, and for what reasons. While such factors might be admitted some significance in philosophy of science, they are rarely attributed a central place in the justification of beliefs in the natural sciences. By looking to the practices of evidence gathering, interpretation and use, we claim that confirmation is intrinsically contextual. This claim amounts to more than the idea that contextual factors are somehow “relevant” to confirmation in some loosely specified sense. Rather, the relationship between hypotheses and evidence is intrinsically contextual in a sense that is epistemic.
A philosophy of evidence so conceived is born out of an analysis of scientific practices, and hence human agency takes centre-stage. Human action is a topic normally associated with philosophy of mind and ethics, though rarely engaged within philosophy of science and epistemology. Placing an investigation of evidence within the context of action offers a unique perspective on evidence broadly. To hypothesis testing, one might ascribe practices such as evidence seeking, gathering, interpretation and presentation. The manner in which these practices are conducted has an impact upon the justification of scientific beliefs when hypothesis testing is viewed as an epistemic activity.
Evidence in the context of action yields fresh perspectives on some old problems. For example, it offers the opportunity to reappraise the ravens paradox. We reformulate the paradox, claiming that the genuinely paradoxical point is not the evidential relevance of seemingly irrelevant objects, but the variable evidential value of one and the same object with respect to a given hypothesis. The central thrust of our claim regarding the ravens paradox, and our view of evidence more broadly, is that observations do not have an intrinsic evidential value. Observations of events or phenomena do not constitute “evidence” in themselves or in isolation; they come to have evidential value as part of an epistemic activity, that is, a coherent testing activity.