the source of continuous and extensive controversy and the occasion for frequent legislation. Self-proclaimed"experts"speak with many voices and can hardly all be regarded as disinterested; in any event, on questions that matter so much, "expert"opinion could hardly be accepted solely on faith even if the "experts"were nearly unanimous and clearly disinterested. The conclusions of positive economics seem to be, and are, immediately relevant to important normative problems, to questions of what ought to be done and how any given goal can be attained. Laymen and experts alike are inevitably tempted to shape positive conclusions to fit strongly held normative preconceptions and to reject positive conclusions if their normative implications- or what are said to be their normative implications Positive economics is in principle independent of any particular ethical position or normative judgments. As Keynes says, it deals with what is, not with"what ought to be. "Its task is to provide a system of generalizations that can be used to make correct predictions about he consequences of any change in circumstances. Its performance is to be judged by the precision, scope, and conformity with experience of the predictions it yields. In short, positive economics is, or can be an "objective"science, in precisely the same sense as any of the physical sciences. Of course, the fact that economics deals with the interrelations of human beings, and that the investigator is himself part of the subject matter being investigated in a more intimate sense than in the physical sciences, raises special difficulties in achieving objectivity at the same time that it provides the social scientist with a class of data not available to the physical 2. Social science or economics is by no means peculiar in this respect witness the importance of personal beliefs and of" home"remedies ir medicine wherever obviously convincing evidence for " expert"opinion lacking. The current prestige and acceptance of the views of physical scientists in their fields of specialization-and,, all too often, in other fields as well- derives. not from faith alone. but from the evidence of their works, the success of their predictions, and the dramatic achievements from applying, their results. When economics seemed to provide such evidence of its worth, in Great Britain in the first half of the nineteenth century, the prestige and acceptance of "scientific economics rivaled the current prestige of the physical sciences4 the source of continuous and extensive controversy and the occasion for frequent legislation. Self-proclaimed "experts" speak with many voices and can hardly all be regarded as disinterested; in any event, on questions that matter so much, "expert" opinion could hardly be accepted solely on faith even if the "experts" were nearly unanimous and clearly disinterested.2 The conclusions of positive economics seem to be, and are, immediately relevant to important normative problems, to questions of what ought to be done and how any given goal can be attained. Laymen and experts alike are inevitably tempted to shape positive conclusions to fit strongly held normative preconceptions and to reject positive conclusions if their normative, implications - or what are said to be their normative implications - are unpalatable. Positive economics is in principle independent of any particular ethical position or normative judgments. As Keynes says, it deals with "what is," not with "what ought to be." Its task is to provide a system of generalizations that can be used to make correct predictions about the consequences of any change in circumstances. Its performance is to be judged by the precision, scope, and conformity with experience of the predictions it yields. In short, positive economics is, or can be, an "objective" science, in precisely the same sense as any of the physical sciences. Of course, the fact that economics deals with the interrelations of human beings, and that the investigator is himself part of the subject matter being investigated in a more intimate sense than in the physical sciences, raises special difficulties in achieving objectivity at the same time that it provides the social scientist with a class of data not available to the physical 2. Social science or economics is by no means peculiar in this respect - witness the importance of personal beliefs and of "home" remedies in medicine wherever obviously convincing evidence for "expert" opinion is lacking. The current prestige and acceptance of the views of physical scientists in their fields of specialization - and,, all too often, in other fields as well - derives, not from faith alone, but from the evidence of their works, the success of their predictions, and the dramatic achievements from applying, their results. When economics seemed to provide such evidence of its worth, in Great Britain in the first half of the nineteenth century, the prestige and acceptance of "scientific economics" rivaled the current prestige of the physical sciences