Rescuing the Assertability of Measurement Reports

Abstract

It is wholly uncontroversial that measurements or, more properly, propositions that are measurement reports are often paradigmatically good cases of propositions that serve the function of evidence. In normal cases, it is also obvious that stating such a report is an utterly pedestrian case of successful assertion. So, for example, there is nothing controversial about the claims that (1) a proposition to the effect that a particular thermometer reads 104 °C when properly used to determine the temperature of a particular patient is evidence that the patient in question has a fever and (2) there is nothing wrong with asserting the proposition that a particular thermometer reads 104 °C for appropriate reasons of communication, etc. when the thermometer has been properly used to determine the temperature of a particular patient. Here, it will be shown that Timothy Williamson’s commitments to a number of principles about knowledge and assertion imply that a whole class of utterly ordinary statements like these that are used as evidence are not really evidence because they are not knowledge and so are (perversely) unassertable according to his principled commitments. This paper deals primarily with the second of these two problems, and an alternative account of the norms of assertion is introduced which allows for the assertability of such measurement reports.