Proc. Indian Acad. Sci. (Earth Planet. Sci.), Vol. 102, No. 2, June 1993,. pp. 283-305. Printed in India. History syndrome OR Popperian credentials of Geology P S MOHARIR National Geophysical Research Institute, Uppal Road, Hyderabad 500 007 India. MS received 12 June 1991; revised 28 December 1992 Abstract. Earth-science is greatly concerned with history. It is argued by some that a historical discipline is not a science. This is contrary to the conclusion from the demarcation criteria of Popper, set to separate science from formal disciplines such as metaphysics, mathematics and logic. Others have spoken of the unity of all sciences. Classification of intellectual activities is based on oenus proximum and differentia specifica. Hence the two viewpoints can be readily reconciled. Earth-science has been criticized variously for being descriptive, inductive, explanatory, etc. Other historical and concrete sciences have also attracted similar adverse comments. These issues are discussed at length to argue that Popper's work should be extended further to define a demarcation of science into immanent and historical. It is also argued that the rignur of cognitive and logical determinants of science is not an adequate reason to embrace sociological models of science. Further, sociological/logical models of science present a misleading dichotomy. Keywords. Demarcation criteria; historical sciences; Kuhnian model; mathematicalization; earth-science revolution. 1. Introduction The purpose of this paper is to discuss whether geology can be a science. Science is a modern catchword. Therefore, everyone is bound to argue that his discipline is science and then proceed to define it. Most such definitions are territorial. The word 'science' is used above in a more specific sense. The question to be discussed is whether geology can be regarded as a science in the strict Popperian sense (Popper 1968, 1979, 1984). Popper has proposed a criterion for demarcating 'science' from other intellectual pursuits such as logic, mathematics, metaphysics, etc. Thus, it is easy to see that the domains excluded from being regarded as scientific are by no means dishonourable or trivial. In the conventional, territorial sense, for example, mathematics would be called a science, but on Popperian criterion, it is not. Popper's criterion is quite exacting. As a result, there is a discernible trend among earth-scientists to move away from Popperian concepts. The strategy is to emphasize the differences from sciences such as physics and to argue that Popper's criterion is not relevant for sciences such as biology and geology (Halstead 1980). This then leads to notions that sciences are inductive or that science is what scientists do. The purpose of this paper is to argue that these responses are unnecessary and unfortunate, as geology can be a science in the Popperian sense. The problem is with the self-image of geologists as well as with the outsider's perception of geology. It is argued that at the level of demarcating 'science' from non-scientific domains, geology has a unity with successful disciplines such as physics. 283 284 P S Moharir Among sciences thus demarcated, it may differ from others. For example, it may then be relevant to recognise physics as an immanent science and geology as a historical one. It is suggested that Popper's work should be extended by developing a methodo- logical demarcation criterion between immanent and historical sciences. It is argued that there is no contradiction in perceiving the unity of all sciences at one level and in dwelling upon their differences at another. In fact, the classificatory principles of 9enus proximum and differentia specifica suggest such an equilibrium. The actual work of scientists is moderated by many pragmatic considerations. However, the definition of what is scientific should not be coloured by these considerations. Thus, the debate between Popperians and Kuhnians (Kuhn 1970, 1976) is quite central to the theme of this paper. It is argued that the two viewpoints are not alternatives to each other but address different problems. A sociological study of scientists should not be used to define science but may suggest how the practice of science could be improved. 2. Sources of doubt and the nature of reaction "One cannot help noting that of late geology is being mentioned less and less frequently among the most important natural sciences", wrote Boganik (1968). "I categorically object to claims that geology has outlived itself, is in a blind alley...", reacted Belousov (1968). The despair and the reaction need an analysis, as geology is, indeed, a troubled science. "General laws are indeed rare in geology. Why is this so? Is geology not amenable to such generalizations or are geologists too little concerned with the universal aspects of geology? Is geology perhaps still too immature to produce generalizations of wide applicability or have geologists found that, for their purposes, general laws are intellectual traps? Or do geologists,because of their subject matter, have to reason somewhat differently from chemists and physicists? Perhaps we, and the biologists who must also perforce travel a comparable, or even more complex, network of paths, have something different in the way of disciplined reasoning to offer the philosophers of science. Just possibly, the philosophers of science err in judging the goals and calibre of a science by the traditionally rigorous sciences of physics and chemistry. May there be goals other than the general laws of physics with their undeniably beautiful simplicity and vast inclusiveness?", asked Bradley (1963, p. 12). Many questions, indeed. Geology has been called an inductive science because geological laws are rare and it uses generalizations instead. Physics and chemistry are put on a pedestal as rigorous sciences. Schrodinger (1956) distinguishes between "physical" and historical sciences, geology belonging to the latter category. Callinga range of sciences 'physical' is synecdochical (Synecdoche is referring the whole by part, figuratively). Popper (1957) avoids a synecdochic usage and calls the two sets of sciences theoretical and historical. Simpson (1963) prefers to call them immanent and historical sciences. Schwinner (1943) calls geology an "explanatory natural science", whereas Spencer (1884) includes geology among concrete sciences. The proper sets of contrasting terms would possibly be abstract/concrete, immanent/historical, deductive/inductive, quantitative/descriptive, predictive/explanatory and nomological/generalizing. One may be tempted to identify physics as an abstract, immanent, nomological, deductive, quantitative and predictive science. But is there any science which is concrete, historical, generalizing, inductive, descriptive and explanatory? Is earth-science such a science? History syndrome 285 There are many problems here, because the contrasting terms listed in pairs above are not antonyms strictly, but may be merely extremes of a spectrum, may arise by bipolar quantization or exaggeration of the spectrum, may be two terms among a finite set, the two may not be immiscible or an antonymity is meant but is actually not met for a variety of reasons, and there may .be a contingent association among some terms and hence some of the terms may be used metonymically. All this has caused a good deal of confusion. This paper is an attempt to understand it, if not to remove it. Physics is, indeed, largely, though not entirely, an abstract, immanent, deductive, quantitative, nomological and predictive science. Some of these adjectives, such as deductive, quantitative, predictive, etc. are taken to be laudatory, but need not necessarily be so. Other adjectives such as abstract, nomological, immanent, etc. impart significant contingent advantages to physics, but may also restrict its scope. Broadly speaking, because physics can attract these adjectives, it has been regarded as a successful and prestigious science. The contrasting terms to these, then, either have derogatory connotations or bring disadvantages or difficulties in their wake. Each one of these disadvantageous or derogatory adjectives has been used for geology (earth-science), not always with justification. Frequently, they have been accepted by the geologists together with the associated value judgement. This paper intends to analyse the issues from many angles. The title is justified on two grounds. The major factor is that geology is a historical discipline but collecting other attributes also, it is a HISTORICAL (historical, inductive, statistical, teacher-dominated (i.e. doxastic), observational, retrodictive, interpolatory, concrete, artefactual and/ingual (descriptive) discipline. 3. History and Science Consider two disciplines, one dealing with immanent aspects of the external world and the other whose basic concern is with the history of it. Obviously, the study of history will bring out the immanent aspects; the first discipline is content with merely those, the second discipline recognizes that knowledge, but is essentially concerned with the historical aspects. CoUingwood (1956) observed that "... whereas science lives in a world of abstract universals, which are in one sense everywhere and in another nowhere, in one sense at all times and in another at no time, the things about which the historian reasons are not abstract but concrete, not universal but individual, not indifferent to space and time but having a where and when of their own, though the where need not be here