Given any rule, however "fundamental" or "necessary" for science, there are always circumstances when it is advisable not only to ignore the rule, but to adopt its opposite. For example, there are circumstances when it is advisable to introduce, elaborate and defend ad hoc hypotheses, or hypotheses which contradict well-established and generally accepted experimental results, or hypotheses whose content is smaller than the content of the existing and empirically adequate alternative, or self-inconsistent hypotheses, and so on.
Paul FeyerabendScience is essentially an anarchic enterprise: theoretical anarchism is more humanitarian and more likely to encourage progress than its law-and-order alternatives.
Paul FeyerabendFacts are constituted by older ideologies, and a clash between facts and theories may be proof of progress.
Paul FeyerabendKnowledge is not a series of self-consistent theories that converges toward an ideal view; it is rather an ever increasing ocean of mutually incompatible (and perhaps even incommensurable) alternatives, each single theory, each fairy tale, each myth that is part of the collection forcing the others into greater articulation and all of them contributing, via this process of competition, to the development of our consciousness.
Paul FeyerabendToday science prevails not because of its comparative merits, but because the show has been rigged in its favour... It reigns supreme because some past successes have led to institutional measures (education; role of experts; role of power groups such as the AMA) that prevent a comeback of the rivals.
Paul Feyerabend