volume two: symposia and invited papers || consensus and dissensus in science

Consensus and Dissensus in ScienceAuthor(s): Robert AckermannSource: PSA: Proceedings of the Biennial Meeting of the Philosophy of Science Association,Vol. 1986, Volume Two: Symposia and Invited Papers (1986), pp. 99-105Published by: The University of Chicago Press on behalf of the Philosophy of Science AssociationStable URL: http://www.jstor.org/stable/192793 .

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Consensus and Dissensus in Science

Robert Ackermann

University of Massachusetts at Amherst

I want to claim that healthy science involves, at all times, a synchronic tensed suspension of consensus and dissensus between working scientists, which provides both the variety of opinion and the agreement in opinion essential to coherent scientific progress. The early philosophers of science and the early sociologists of science seem both to have worked with an oversocialized conception of scientific thought, philosophers regarding lapses from postulated objective standards of rationality as the unfortunate intrusion of emotional and personal factors into scientific reasoning, and the sociologists viewing the breakdown of shared values within research groups as the inexplicable accompaniment of emerging anomalies. More recently, sociologists working with a conception of the social construction of scientific thought have reversed the emphasis, suggesting that consensus is essentially a temporary and unstable phase in scientific development, and philosophers have recently crafted a new form of philosophical scepticism for science in suggesting that it is impossible ever to establish that a genuine consensus exists between scientists. The correct view, I think, lies somewhere within the space suggested by variants of these extreme positions.

My model for valuing simultaneous consensus and dissensus comes from the well known virtues of variation and selection in the exploration of new ecological niches in evolutionary theory. Where a new niche is explored, it's easy to see the intuitive plausibility of the idea that a group of biological agents can minimize search time in locating a maximally adaptive strategy in the new niche by deploying as much variation as possible, while retaining a form of communication that allows a common measure of the success of the variants. Variation and selection can be studied as a strategy in colonizing species, in capitalist competition for new markets, in technological competition to satisfy demands for new forms of objects and materials, and also in scientific theoretical competition for explanatory superiority in the face of new kinds of scientific data. The mechanism of variation and selection can illuminate only the initial colonization of new areas, since surviving adaptations in settled domains produce a different kind of situation in which entry costs for new variants in stable established environments can exclude variants that might have proven successful if they had been introduced earlier into the environment.

If a suspension of variety and selection is a sound metaphor for describing the efficient exploration of new domains in many situations, the utilization of the implied scheme in any specific domain depends on finding several supporting mechanisms: a

PSA 1986, Volume 2, pp. 99-105 Copyright ? 1986 by the Philosophy of Science Association



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specific mechanism for producing variety; a specific mechanism for selecting successful variants; a specific mechanism for distancing agents from the local environment so as to prevent an overadaptation that would prove lethal under environmental shift; and a specific form of feedback that would permit the reproduction of selected agents in the environment over time. If features in the real world provide the relevant selection pressure in the case of biological or market competition, scientific theorizing seems initially resistant to the metaphor in that there is no obvious analogue to death or bankruptcy. Scientists seem to confront an abstract environment in which they can hang on to personal beliefs no matter what, or simply restrict their application to carefully selected data, working with cultivated forms in a scientific greenhouse that is protected from larger influences.

If we begin by restricting the mechanism of variation and selection to the conscious articulation of divergent ideas and the conscious consensus that may be produced in public argument, the evolutionary analogue is pretty vacuous. In this environment, it's not clear why scientists would normally dissent from existing consensus, since they might pursue perfectly safe and well rewarded careers within existing consensus. The factors that can put scientific theorizing into reproductive motion over time are factors that escape measurable public consensus. Neither dissensus nor consensus can be explicated in the conscious articulations of scientists. Kuhn's most lasting impact on the philosophy of science should be his demonstration that acculturation into a scientific community in graduate school produces a scientific unconscious that actively participates in consensual valuations, and continues to do so even where some features of the unconscious are exposed as such, analytically brought to light over one's career, and explicitly rejected (Kuhn 1970, pp. 35-51). The unconscious aspects of dissensus, on the other hand, have sources that are rarely talked about in a positive way; personal ambition, relationships of subservience to charismatic thinkers, and distaste for certain scientific personalities. Yet all of these play a positive role in forcing dissensus. If dissensus fills the space explored by scientific competition, and consensus provides a comparative evaluation of the deployed positions, any attempt to mechanize these procedures in all of their aspects by formal analysis would miss at least some of the dynamic aspects that provide the movement in the dispersal of competitors, as well as the movement involved in consensual evaluation and adjustment.

In biological cases, appropriate distancing mechanisms for buffering adaptation are provided by species sensory systems that reduce the total complexity of the environment to a sensory field that is the focus of species adaptive strategies. For scientific purposes, environmental complexity is reduced in contemporary science by instrumentation. Data derived from instrumentation that is "smoothed" into summary form provides the objective communal environment for theoretical adaptation. Perception without instrumental resolution, by contrast, is typically dissensual in science. In everyday life, two people who disagree as to whether a third person is kindly or not may each see the third person's actions differently, and they may each deal with any awkward actions by attributing them to pretence or momentary lapse. When theory is directly involved with perception, disagreement is hard to resolve. At the same time, two people may be forced into agreement about the height of a third person as a result of a joint measurement with the primitive instrument called a yardstick. Ordinary perception, in many cases, is interwoven with theoretical perspectives that cannot be bracketed out by more rigorous attention to the objects of perception. Scientific instruments, contrary to the phenomenological tradition that has studied them most extensively, would not work as they do if we could treat their data in every case as extentions of ordinary perception. As science advances, new instruments can cast up strange and opaque data which set forth new textual environments that call for new theoretical explorations. The evolutionary model is designed to illuminate explosive explorations of such new data texts, and regards these new texts and the resulting colonization by theory as the anchor of scientific progress. When the data lose



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novelty and become transparent, and are taken by theory as revealing permanent features of the real world, measurable scientific progress in theorizing the data is almost certainly slowing down, if it hasn't stopped; evolution gives way to exposition.

Data text forces a democratic consensus, as one can see by imagining it otherwise. Suppose that some scientists could literally see better than other scientists, as though their eyes had microscopic or telescopic powers by comparison to the vision of other scientists. The data provided by such scientists couldn't be obtained by others, and ordinary scientists would be forced to study the thaumaturgic writings of the leading mys- tics. Except for those nodal points where scientific investigation first begins to diverge from established perception, before appropriate instruments are developed for investigation, scientific instruments are essential for dissociating experimenters from their data, and to providing common consensual data over which scientists may propose articulated explanatory theories. That such consensual data is expected as a foundation for theoretical discussion is shown indirectly wherever the potentially important experi- mental results reported by a particular scientist are not found to be repeatable by others, triggering the form of anxiety and accusations of fraud that are associated with such circumstances.

It is worth looking at the effects of an increasing technological sophistication in scientific instruments, as well as the discovery of new kinds of instruments and the application of older instruments to new objects of study, since this consensual basis for scientific change has been systematically underplayed in the philosophy of science, which has concentrated on the succession of theoretical ideas in various branches of science, and has treated data as relatively unproblematic bits of text. Data text actually presents scientific theorizing with a special hermeneutical problem, since the data text of science is always expanding, and it sometimes shows jumps or gaps, revealing new niches for theoretical exploration, when new scientific instrumentation appears. Science can be divided up into data domains construed as areas of data text bounded by a consensus among scientists as to what kinds of instrumentation directed to what kinds of objects produces a swatch of text that is to be theoretically explained. We can regard theories as attempts to read such data domains.

It is probably not possible to say in advance, by application of methodological con- siderations, when new data should be regarded as forcing variation and selection of new theory, and when it should be regarded as a refinement of existing data whose reading is expected to be a refinement of already existing theory. Neither new data nor new theories normally wear their meanings on their sleeves. The point of invoking hermeneutics, arguing that scientific theorizing is at first equivalent over new domains to the hermeneutical problem of reading partially opaque data, is to invoke the hermeneutical circle. Dissensus must occur in science so as to find out what both data text and theory text may mean, but this dissensus must be explored between individuals in an insti- tutional context that permits a communicative interaction between scientists with respect to the assumed borders of data domains that can ultimately issue in workable consensus. The expansion of data text by an improving scientific instrumentarium, an essential motor of scientific growth, forces both consensual and dissensual patterns of scientific interaction. Where the text is settling down in a data domain, and the data are becoming transparent, consensus typically heightens selection pressure, and causes the number of acceptable theories to lessen. Where the text is novel, variation of new theoretical discourse will be triggered by the standard mechanisms of individual desire for scientific recognition, and selection pressure on this confusion of theoretical discourses awaits refinement and standardization of the instrumentarium. Dissensus of an almost purely hermeneutical kind will be essential to the exploration of ambiguities and opacity whenever new instruments produce new data text. Perhaps these observations are sufficient to indicate why the dialectical interplay of data and theory that has been immanent in the past philosophy of science as part of the process of reaching consensus, must be



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coupled with a positive valuation of dissensus as a mechanism for producing variation in the possible meanings of new data text that is being explored.

If the meaning of new data text was obvious when it was first introduced, so that the only problem for scientific progress was to produce variation and consensus in theory formation, science would rest on a consensual basis, and dissensus would be an unwelcome interlude on the road from data consensus to theoretical consensus. Philosophers of science have perhaps missed the ambiguity of new data text because their examples are typically drawn from scientific history, and the established clear meaning of data is used in these examples to test current methodological suggestions. But between the past and the present, an evolutionary process of variation and selection of meanings for data and theory statement has already occurred. A present consensus about the past, and a common understanding of the significance of past data, cannot be extrapolated to novel data text in the present because this intervening evolutionary process has not yet occurred. With respect to the meaning of the present, we often have to wait for dissensus to deploy possible meanings, and we often have to wait for selection among these meanings to occur as the present data text expands, although the process of variation and selection with respect to meanings can be forced by deliberate scientific competition. The hermeneutical presuppositions of the past philosophy of science suggest that science is basically a matter of obtaining new data and classifying it under theoretical extensions. Science is more exciting and dangerous than that, and I might summarize this point by suggesting that where science seems to be proceeding most rapidly, there's a sense in which it doesn't yet know what it is talking about. This is why dissensus is essential to scientific progress, and why the individual desire for recognition by other scientists that can fuel the intensity of dissensus must be positively valued if science, such as we have known it, is to have a coherent form of growth.

If the meaning of new scientific data text and theory text can't be established at the moment of production in interesting cases, it provides a motivating optimism for many scientists in that obscure or poorly funded scientists may in fact be first to recognize what will become consensual opinion, thus reaping the benefits of the reward system of science. There is a consensual element even in dissensus. Papers often propose a consensus in advance, inviting readers to join the described position as it is objectively given in the paper for the purposes of discussion. Scientists need to reduce the complexity of expanding data domains in order to have something reasonably focussed to talk about, and a convenient way to do this is to objectify the positions of laboratories and individuals in a debate over the significance of new data text, even if the discus- sants may interpret these positions somewhat differently below the level articulated in the staking out of positions in debate. The resulting ambiguities allow for some room for movement in interpretation without loss of interpretive continuity or identity, so that debate doesn't have to be refocussed in its terminology every time a moderate shift in interpretation is proposed, and yet the reward system for individuals can function satis- factorily because of the way in which suggested interpretations are labelled.

Dissensus is also pursued in the gossip and the humor that permeates any scientific enterprise. The advantage of gossip is that the kind of citation and articulation required for public debate with published opposition is bypassed, permitting rapid interpretive shifts and explorations without public costs, such as published retractions or alterations in viewpoint. In public debate, Mertonian norms apply like debating rules in college debates, to control controversy in the interests of fairness that scientific motivation and morale require. When philosophers started to investigate science from the top down, by studying published papers, they found the logical structure of public scientific presenta- tion, and assumed that the observed clash of logical structures against canons of rationality was somehow the mechanism of scientific progress. Sociologists, who also started by examining public scientific documents, repeated the error of supposing that the layer of public debate captured the consensual norms of science. More recently, a deeper



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penetration of the layer of public debate by philosophers and sociologists has seemed to tear the mask of objectivity from public rationality, producing a troublesome worry that the objectivity of science finally runs out into the sands of individual interpretive scepticism. Laboratory studies may yet turn this direction around again, since they can suggest that the layer of dissensus in local conversation is conjoined to a hermeneutics of emerging consensus about the meaning of opaque data text that explains why both dissensus and emerging consensus are essentially interwoven in scientific discourse.

If this sketch of mechanisms allows variation and selection a foothold on the terrain of exploring scientific practice, the worry of many has been that it can only describe the path of localized scientific enquiry, without providing a comparative overview of these paths that would permit sound judgments about scientific objectivity. If the search mechanism is observed in nature, how can we assume that it has normative consequences for an understanding of how science should proceed, since the possibility of conscious science policy doesn't seem to have an analogue in nature? Although prescription and description are analytically quite distinct, where selection on variation has occurred, they are frequently rather closely related. Consider the everyday example of painting a house with a paint bucket, paint brush, and ladder. There are normative rules for painting procedure and ladder placement, presumably derived from injury, death, and embarrassment suffered by the pioneer painters of the past. And yet perhaps no house is ever painted entirely according to rule. There's always a bush or a slope exactly where the rules require optimal placement of the ladder, and unusual house construction, always present, calls for unusual postures and adjustments in reaching awkward places. In another world, of course, houses may be painted in some more efficient way that we know nothing of. What I'm suggesting is that the experience of all the painters on earth, including the dead and injured of the past, and those whose paint jobs have been ridiculed by their friends, suggest some pretty sound normative rules that work well with the necessary local adjustments. Dissensus and consensus as combined in the history of theoretical colonization of data domains will take various specific courses, and show various specific rates of development, depending on local peculiarities of past instrumentation and past theoretical practices. The normative counsel derived from the role of consensus and dissensus in the hermeneutics of theorizing over novel data text suggests that dissensus is a permanent, valuable aspect of scientific progress. If the evolutionary model can be specified in terms of its mechanisms in the way I have suggested for colonizing theorization, the normative aspects of the process would be tightly interwoven with its description in various concrete examples. In the absence of an alternative account of the fine grained adjustments observable over time in scientific thought, this may be as close as we can come to justifying pretty much what happens in science wherever the conditions of the model are satisfied.

All talk of progress has been relativized to data domain colonization by this model, and the general question of progress in larger areas of science has not been explicitly addressed. To say that science is progressing, or some traditional field of science is progressing, is to refer to an ongoing tangle of data domains over which progress and objectivity are rather differentially distributed. Only if novel data domains were being produced which were so opaque that variation and dissensus couldn't get a footing would it be reasonable to say that science exhibited neither objectivity nor progress. So far, this hasn't happened.

There will be some who will suspect that all of this is an elaborate attempt to find the prescriptive in the descriptive, and hence an effort to veil a perfectly obvious fallacy. I have tried only to find some justification for positively valuing simultaneous consensus and dissensus of the kind that seems associated with all of the growth points in science. My suspicions are directed at those who would lay down rational models for scientific progress, and then wonder that the presence of certain kinds of consensus or



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dissensus indicated that scientific practice simply failed to measure up to the demands of rigorous methodology. As simultaneous consensus and dissensus seem to occur in conjunction with scientific progress in novel data domains, I have assumed that something immanent in the conditions of scientific practice must repeatedly cause this suspension to occur, and that it must therefore be a feature of scientific progress, no matter whether the actual rate of progress could somehow be considered optimal or less than optimal. Perhaps the rate of progress on particular novel data domains can be increased by specific suggestions for local procedures and method, but I wouldn't expect this to be deducible from a philosophical account of science. That would be like trying to deduce Chicago from a monistic conception of substance. I have tried only to indicate that simultaneous consensus and dissensus would be expected if the general characterization of successful biological colonization of new ecological niches could be carried over to the theoretical colonization of new data text in science, and I have suggested that this characterization can be transferred so as to illuminate the presence of both consensus and dissensus in science, as well as a few other features of scientific progress. I do not claim that it can explain everything.

The normative aspects of variation and selection can be retained only when it is not the case that variants are excluded from the selection process. Evolutionary episte- mology would reduce to Mill's liberalism if the presuppositions of complete exposure to selection pressure were met for every variant. Mill's theory depends on a notion of truth equivalent to complete adaptation to a fixed environment, however, so that the distancing of instrumentation and the recognition of environmental shifts, not recognized in Mill's libertarian arguments, produce for general evolutionary episte- mology the possibility that selection pressure will result in an adaptive mix of explanatory theories, a hedge against change, that preserves a distinction between Mill's structure and theoretical colonization in science (Mill 1859). The normative thrust of both, however, and hence the legitimation of dissensus and consensus, is abruptly undercut when exclusions from variation and selection are present, as when adaptation has already occurred in a manner that prevents the entry of novel forms into the established domain, novel forms that might have been able to survive in the environment before that adaptation had occurred.

If dissensus is not positively valued, the situation just described may not seem alarming to empirical investigation. There may be more apparent consensus than in the past if missing voices are not noticed, but this is not necessarily a sign that selection pressure has been applied to all of the variants available to the relevant domain. It may be harder to find dissensus if it is concealed in the process of jumping onto bandwagons in order to find funding for research, accelerating the swings of scientific fashion. Dissensus and consensus can become a matter of the dissensus of silence, a failure to measure one isolated center of research against another. Variation and selection would then be restricted to domesticated growths on carefully chosen data texts shielded deliberately from wider selection pressures. Such indicators may trace the beginnings of the rigidities of old age for science. Old age is compatible with evolutionary description, and with wisdom or folly. The declining selection pressure means only that description and prescription are decoupling in analysis. It may be that the philosophy of science will have to become a form of the geriatrics of science in advanced industrial societies, working with a more subdued conception of the maintenance of reasonable health during decline. These reflections may be sufficient to indicate that the conditions for positively valuing the suspension of consensus and dissensus are not vacuous, as they may not exist everywhere where we can recognize science. In fact, colonized data domains that become completely stable are fixed, non-growing cells within the structure of science. A science composed only of such cells could live only until a decisive shift in the environment. Philosophical recognition of the situated virtues of suspended consensus and dissensus, finally achieved, could perhaps turn out to illuminate the past, but to only cloud the present. I hope that this is not the case.



105 References

Kuhn, Thomas S. (1970). The Structure of Scientific Revolutions. Second edition, enlarged. Chicago: The University of Chicago Press.

Mill, John Stuart (1859). On Liberty. Indianapolis: Bobbs-Merrill Educational Publishing, 1982.



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