The study of cognitive differences by means of rational inquiry is a legitimate goal of epistemology and cognitive sciences. From the results of such an effort arose a number of rules seeking to establish some workable guidance for the appropriate cognitive conduct of the human mind but these rules are not yet advanced to such an extent that they may serve as a categorical prescription for the error-free search of truth. Current advancements in science result from collective activity of different agents, past and present, including their triumphs and failures. An analysis of the historically erroneous theory of combustion is offered here as an alternative to the direct study of cognitive processes of contemporary actors. It will be shown, that scientific progress is positively influenced by various channels, including faulty reasoning, serendipity and even pure chance. In recent times, or so it seems, a tendency became fashionable to judge and condemn erroneous thinking in moral terms on the grounds that such modes of cognition facilitate the rapid growth of so called pseudoscientific theories. However, such attitude obscures the existence of inscrutable and yet so important aspects of human mental activity.

Keywords: epistemology, philosophy of science, pseudoscience, cognitive psychology. epistemic virtues and vices, moral value judgments