It is generally acknowledged that attempts to demarcate science from non- or pseudoscience, based on a priori standards, have failed. Here I discuss a values-based approach, advocated by Feyerabend in his paper Realism and Instrumentalism, in which he wrote:
The […] distinction between ‘respectableâ€™ people and cranks […] does not lie in the fact that the former suggests what is plausible and promises success, whereas the latter suggest what is implausible, absurd and bound to fail. It cannot lie in this because we never know in advance which theory will be successful and which theory will fail. It takes a long time to decide this question, and every single step leading to such a decision is again open to revision. Nor can the absurdity of a point of view count as a general argument against it. It is a reasonable consideration for the choice of oneâ€™s own theories to demand that they seem plausible to oneself. This is oneâ€™s private affair, so to speak. But to declare that only plausible theories should be considered is going too far. No, the distinction between the crank and the respectable thinker lies in the research done once a certain point of view is adopted. The crank usually is content with defending the point of view in its original, undeveloped, metaphysical form, and he is not at all prepared to tests its usefulness in all those cases which seem to favour the opponent, or even to admit that there exists a problem. It is this further investigation, the details of it, the knowledge of the difficulties, of the general state of knowledge, the recognition of objections, which distinguishes the ‘respectable thinkerâ€™ from the crank. The original content of his theory does not. If he thinks that Aristotle should be given a further chance, let him do it and wait for the results. If he rests content with his assertion and does not start elaborating a new dynamics, if he is unfamiliar with the initial difficulties of his position, then the matter is of no further interest. However, if he does not rest content with Aristotelianism in the form in which it exists today but tries to adapt it to the present situation in astronomy, physics, and micro-physics, making new suggestions, looking at old problems from a new point of view, then be grateful that there is at last somebody who has unusual ideas and do not try to stop him in advance with irrelevant and misguided arguments.
I believe this is a view developed from Millâ€™s arguments in On Liberty, particularly the second chapter. For Feyerabend, the demarcation of good and bad ideas occurs in terms of values, not facts or adherence to method. In his detailed study, Feyerabend and Scientific Values, Farrell identifies four such values advocated by Feyerabend:
1. Theoretical traditions - identifying knowledge with universality and with theories as the form of information, seeking laws via a standardised, logical form of reasoning (cf. A Farewell to Reason, p118).
2. Historical traditions - placing an emphasis on plurality and the particular, reasoning via stories, lists and analogy, and only resorting to rules when useful. Here knowledge has more of an instrumental role as a tool, with the relationship between different tools one of usefulness rather than fitting into a coherent whole.
3. Tenacity - retaining interest in or advocacy of a theory in spite of setbacks or evidence to the contrary, insisting that it retains merit and that apparent facts to the contrary may eventually be reinterpreted and count in its favour. Sometimes the reasoning behind a theory or its explanatory ability may be taken to outweigh conflicting experience, or refuting experiments may be flawed. Tenacity encourages work to continue even though the theory may be wrong, since without further investigation matters can hardly be expected to be otherwise.
4. Proliferation - the drive to develop a multiplicity of theories in order to strengthen our existing ideas or replace them with alternatives. According to Mill, “[s]o essential is this discipline to a real understanding of moral and human subjects, that if opponents of all important truths do not exist, it is indispensable to imagine them, and supply them with the strongest arguments which the most skilful devilâ€™s advocate can conjure up.”
Clearly these values are in conflict with each other and form two deliberately idealised and opposing poles. For Feyerabend, attempting to find theories that are empirically adequate may lead to a solution that is disconnected or inconsistent, whereas seeking a universal solution can leave out the quirks and eccentricities of what people actually experience. Tenacity and proliferation are bridges between the two: empirical adequacy is departed from because tenacity prompts us to be dissatisfied with a multitude of separate and overlapping theories and to continue working towards a single answer; we proliferate theories because a unified approach fails to account for all phenomena, so we try to understand theories and potential answers better by comparing them with others.
Note that these are not intended to be rules but are instead values, the dynamic between which drives creativity and exploration. As soon as they are interpreted as applying everywhere they fail to capture science and even restrict it, but as tendencies to be encouraged they stimulate imagination and invention. This is neither anarchistic nor revolutionary (as people are inclined to view Feyerabend) but it avoids setting limits and arbitrarily cutting off entire areas of enquiry from scientific exploration, and yet still provides us with means to understand when we are dealing with cranks who have no interest in learning anything.