Keywords

Introduction

How scientists come up with new ideas, concepts, hypotheses, and theories is usually different from how they present and argue for them in published research articles and textbooks. Philosophers of science have conceptualized this difference into a more rigorous distinction between the context of discovery (for generating novelties) and the context of justification (for validating them). This distinction is also often aligned with the distinction between the descriptive (how science actually works) and the normative (how it ought to work).

History of the Discovery–Justification Distinction

With the development of the new sciences in the early modern period, philosophical discussions on scientific discovery arose in attempts to establish the scientific method. Francis Bacon (1561–1626) and René Descartes (1596–1650) offered the most prominent philosophical models among others to explain and encourage scientific discoveries. Their ideas, inspired by the emerging new scientific practices, in turn prompted groups of natural philosophers to embark on making new findings especially through concerted efforts via newly founded scientific societies. For Bacon, knowledge was gained securely through an inductive process, starting with the collection of unbiased observations and progressing toward more theoretical generalizations. For Descartes secure knowledge could only begin from indubitable foundations, from which the rest was logically deduced. In either the Baconian or the Cartesian view of ideal knowledge, there was no explicit distinction between discovery and justification, as their belief in the existence of the “scientific method” was supported by the conviction that the best method for making new discoveries was at the same time the best justification of the discoveries.

This conviction, however, was put to question starting from the early nineteenth century. An alternative view of scientific discovery, popularly captured by the “Eureka” moment and reinforced by the Romantic image of the scientific genius, made it difficult to conceive that there could be any fixed method for discovery. On the other hand, appreciation of the use of hypotheses in scientific practice paved the way for the rise of hypothetico-deductivism, which argues that the scientific method only concerns the testing of hypotheses, regardless of how they are conceived (Nickles 1980, Chap. 6). These developments drove a wedge between discovery and justification, culminating in the categorical distinction between scientific discovery and scientific justification by leading empiricist philosophers such as Hans Reichenbach (1891–1953) and Karl Popper (1902–1994) in the first half of the twentieth century. According to Reichenbach, the “context of discovery” is subject only to psychology, which deals with the processes of thinking as they actually occur. While any scientific theory consisting of a group of propositions can be justified by being in a correct logical relationship with observational statements, the discovery process was not amenable to this sort of “logic” for philosophers to seize upon. (Thus, there is a great irony in the English title of Karl Popper’s masterpiece in the philosophy of science, The Logic of Scientific Discovery; there is no similar irony in the original German title, Logik der Forschung). Discovery is a subject of all kinds of empirical research, historical, sociological, and psychological. Epistemology is and should be confined to the “context of justification,” in which the propositions produced in science are reformulated and rearranged so that their structures and logical relations are made explicit. Epistemology thus considers a rational reconstruction of scientific practice, rather than the actual practice of scientists. The “context distinction” between discovery and justification has exerted a deep influence on philosophers of science through the century (Nickles, Chap. 1).

The terms of debate began to change again, however, with the demise of the orthodoxy in Anglophone philosophy of science that was the legacy of the logical positivism of the Vienna Circle. For post-positivists such as Thomas Kuhn (1922–1996) and Paul Feyerabend (1924–1994), it is theories that give meaning to observations, not the other way around (Chalmers 1999, Chap. 8). Therefore, any truly novel discovery, even of facts, can take place only if it is directly tied to theoretical change. During a phase of “normal science,” in which the ruling paradigm is not challenged, facts can pile up more or less cumulatively, and theories are improved only in a trivial way; hence, there is no philosophical problem about justification or discovery. But in the process of a scientific revolution, new theories and facts are discovered together because facts can only be assigned their meaning by underlying paradigmatic theories. Therefore, such discovery, according to Kuhn, is not a matter of a “Eureka” moment, but a difficult protracted process of adjustments of establishing paradigms and their relevant facts together that need to be agreed upon by a whole scientific community and then passed on to the next generation through laborious pedagogical efforts (Schickore and Steinle 2006, Chap. 7). Justification only happens through such processes of negotiation, in which Kuhn famously declared that there is no higher standard of judgment than the assent of the relevant scientific community. Kuhn’s stance not only upset the traditional philosophers due to its anti-rationalistic implications even for the context of justification, but it also brought justification and discovery back together, this time in an untidy mix.

The emphasis on the social processes highlighted by Kuhn in his discussion on scientific discovery has been fully adopted and extended by social constructivists. Historians and sociologists of the constructivist bent have offered instructive case studies revealing diverse disagreements and complex negotiations among self-claimed discoverers and their allies or followers, and their political, social, and professional agendas with respect to the “authorization” of discovery. As shown in the classic case of the “rediscovery” of Mendel, scientific discovery in the social constructivist picture is a retrospective affair, a product of a discussion among relevant practitioners in a given discipline; a discovery as an achievement, its meaning, and its discoverer, it is argued, can only be retrospectively evaluated and acknowledged. In these social constructivist construals of scientific discoveries, the scientific realist commitment which implicitly underlay the traditional philosophical discussions has been explicitly problematized and severely attacked. There are various types of antirealists in this debate (Chalmers 1999, Chap. 15; Psillos and Curd 2008, Chap. 21): constructivists often draw on Kuhn’s notion of incommensurability, while a majority of antirealist philosophers base their arguments on skepticism or agnosticism about unobservable entities, as in the philosophy of constructive empiricism advanced by Bas van Fraassen (1941–). What these antirealists have in common is that they do not take the notion of discovery for granted, as they reject the realist connotation implied in the term (if something has been “discovered,” it must really exist). For them it is meaningless to distinguish sharply between discovery and construction, both being processes of finding a solution to a problem or contriving an empirically adequate theory to save the phenomena.

Discovery and Justification in Practice

With the long-lasting belief that there are some genuine methods for scientific justification (even if no simple logical algorithms), philosophers of science have principally explored its different strategies and procedures largely under the rubric of confirmation theory: inductivism, hypothetico-deductivism, Bayesianism, and value-laden comparative theory appraisal (Psillos and Curd, Chaps. 10, 11, 28, 31, 47). Yet, with the recent rise of a more practice-oriented view of science, it is now generally acknowledged that even justificatory practices are contingent on the context, not captured by either an ahistorical formalism with the belief in a pure observational language or a theory-dominated holism notoriously represented by Kuhn’s notion of paradigms. This sensitivity to context leads us to ask in which epistemic situation a knowledge claim is justified and which method of justification can be intelligibly demanded of the knowledge claimant or rationally accepted by the relevant practitioners; this means accepting that an agent attempts to justify a scientific knowledge claim to her relevant epistemic community participating in specific epistemic activities with shared epistemic goals.

Notwithstanding the theory-ladenness of observation, for example, not all observations in practice are on a par. Some are more stabilized and robust in a relevant setting as is the case with middle-level regularities, being relatively independent of high-level theories and their changes, which could function tentatively as an empirical foundation to test and warrant a novel knowledge claim. Yet, these regularities can be made more elaborated and refined in terms of precision, scope, and the like through iterative processes. Moreover, there are various ways of testing a knowledge claim which are to be chosen by the actor depending on the relevant aims, resources, audiences, and even metaphysical values and principles. Even any plausible skepticism of induction could be avoided, for example, in a very well-controlled experimental setting which successfully removes as many extraneous non-observational hypotheses as possible. These, all in all, come down to a self-corrective and pluralistic attitude to scientific justification.

A shift of emphasis to scientific practice is more than welcome in relation to the study of scientific discovery, as traditional philosophical interest in the subject has been meager or just skeptical. Of course, it should be acknowledged that there has been considerable interest in “abduction,” often equated with “inference to the best explanation,” as a plausible “logic” of scientific discovery (Psillos and Curd, Chap. 18). There are even several automated discovery tools, as is well illustrated by statistical techniques and computer simulation programs to find out from given data abstract correlations or patterns or models, though it is still out of their reach to get at any deep theories or hypotheses. Yet, it would not be a surprise to see that existing philosophical frameworks are helpless when confronted with a sheer diversity of scientific discoveries in practice, given that typical philosophical discussions of scientific discovery pay exclusive attention on the discovery of theories. Therefore, it would be helpful to ask: What sorts of things do scientists discover in practice? A rough taxonomy should include theories and hypotheses, principles and laws, facts and phenomena, observable and unobservable entities, properties and processes, and the like. This again leads to another intriguing question: Are there different patterns in scientific discovery depending on what is discovered? For example, it is argued that discovering unobservable entities like electrons is inextricably interconnected with justifying their existence somehow. Here the complicated link between the contexts of discovery and justification comes up again (Schickore and Steinle, Chap. 12).

The discovery of unobservable entities illustrates that our understanding of scientific discovery would be enriched by a process model of scientific discovery. Anything that looks like a “Eureka” moment should be seen as a nodal point on a long research trajectory in ongoing interaction with the relevant research community; in this sense, the meaning of a discovery is often transformed as it is consolidated, often in ways that are not in accord with the original discoverer’s own conception of it. The discovery of unobservables also links up with debates on scientific realism. Here, the descriptive task is to investigate the reason why the actors accept that something is “discovered,” not “constructed” or “invented.” Yet, normatively, the positions will be divided: entity realists would argue for the discovery of manipulable unobservables, whereas antirealists might recommend a skeptical or agnostic attitude toward them. One of the ways out of this impasse could be to ask again in which context the question of existence or truth is meaningful or useful. That is, we could investigate various ways of accessing reality manifested and developed in scientific practice and evaluate their ontological and epistemological implications.

Implications for Science Education

What does the discovery–justification distinction imply for science education? It seems that the distinction is implicitly but strongly present in ordinary educational settings: students are typically not taught about the process of discovery, though they are usually given some justifications for the theories they spend countless hours learning to apply. In fact they only tend to get told about discoveries if there are striking stories associated with them (e.g., Fleming’s penicillin mold, Newton’s apple, Kekulé’s dream of snakes biting their own tails); these discovery stories are normally used to enhance the “human interest” in science, not especially to teach about real history or methodology.

One may question why we should want to teach students anything substantive about the processes of scientific discovery or justification. On the side of justification, at least many would agree that knowing how scientific justification works is indispensable for acquiring a proper critical appreciation of scientific knowledge; it is difficult to imagine how people lacking a sense of methods of justification can be competent to judge for themselves controversial issues such as policies concerning global warming, the risks associated with vaccination, or the legitimacy of including intelligent design in curricula. But how about discovery? For students who will go on to become research scientists, it is important that their habits and expectations do not become hampered by distorted or overly restrictive notions of how discovery works. Advocates of discovery learning, inquiry-based learning, and problem-based learning would go much farther to argue that going through one’s own process of discovery is the best way to learn anything at all (see Schwab (1960) for an early exposition).

Cross-References