Abstract

The reader will be a patient one indeed who has not long since raised in his mind what appear to be pertinent and pressing problems concerning the description of experimental method that has so far been given. These questions are mainly concerned with matters of omission: for example, we have said that if a lack of control is shown, then the image should be changed. But how changed? What principle or method guides the selection of a new image of nature when the old is no longer permissible? Or again, we have said that “observations should be made“. But what is an observation? What principle or method guides the experimenter in deciding which of his activities are observations?