Within contemporary science, it is common practice to compare data points to the _average_, i.e., to the statistical mean. Because this practice is so familiar, it might at first appear not to be the sort of thing that requires explanation. But recent research in cognitive science gives us reason to adopt the opposite perspective. Research on the cognitive processes involved in people’s ordinary efforts to make sense of the world suggests that, instead of using a purely statistical notion of the (...) average, people tend to use a value-laden notion of the _normal_. This finding about ordinary cognition gives us reason to rethink certain familiar facts about scientific practice. In particular, it suggests that the fact that scientists so often make use of the statistical average should be seen as a highly surprising fact, the sort of thing that calls out for explanation. To understand it, we turn to work in the history of science, and especially to work on the ways in which the practice of science changed over the course of the 19th century. (shrink)

John Venn is known as one of the clearest expounders of the interpretation of probability as the frequency of a particular outcome in a potentially unlimited series of possible events. This view he held to be incompatible with the alternate interpretation of probability as a measure of the degree of belief that would rationally be held about a certain outcome based upon the reliability of testimony and other prior information. This paper explores the reasons why Venn may have been so (...) opposed to the degree-of-belief interpretation and suggests that it may have been a way for him to resolve a conflict in his own mind between his ideas of proper scientific methods of inference and the religious beliefs that he held as a young man. (shrink)

The ArgumentIt is often assumed that all sciences travel the path of increasing precision and quantification. It is also assumed that such processes transcend the boundaries of rival scientific disciplines. The history of the personal equation has been cited as an example: the “personal equation” was the name given by astronomers after Bessel to the differences in measured transit times recorded by observers in the same situation. Later in the nineteenth century Wilhelm Wundt used this phenomenon as a type for (...) his experiments on reaction times. For historians of psychology, this has been taken to be an exemplary case where quantified laboratory science rescued astronomy by showing that this was really a psychological phenomenon measurable only in complication experiments. This paper challenges this story. Astronomers neither ignored, nor despaired of, the personality problem. Instead, the managers of the great observatories developed a new chronometric regime of vigilant surveillance of subordinate observers. The astronomers' solution was thus intimately connected with social and material changes in their way of life: a division of labor in the observatories, a network of observing sites, a mechanization of observation. The paper documents these changes and then presents a study of one case where managers, amateurs, and psychologists clashed for authority over the personality problem. Measurement is given its meaning when situated in specific contexts of styles of work and institutions. Disciplines give meanings to values, and often resist attempts by others to redefine these meanings or to gain authority over measurement. Quantification is not a self-evident nor inevitable process in science's history, but possesses a remarkable cultural history of its own. (shrink)