Concept in the philosophy of science
Bold hypothesis or bold conjecture is a concept in the philosophy of science of Karl Popper, first explained in his debut "The Logic of Scientific Discovery" (1935) and subsequently elaborated in writings such as "Conjectures and Refutations: The Growth of Scientific Knowledge" (1963). The concept is nowadays widely used in the philosophy of science and in the philosophy of knowledge. It is also used in the social and behavioural sciences.
Brief explanation.
Popper's argument is that the growth of scientific knowledge progresses by means of formulating "bold" hypotheses, and trying to refute (disprove or falsify) them. Popper believed that:
 ;templatestyles src="Template:Blockquote/styles.css" / ;"Bold ideas, unjustified anticipations, and speculative thought, are our only means for interpreting nature: our only organon, our only instrument, for grasping her." 
He makes this point more specific in a 1953 lecture, where he argues that, if we aim to explain the world, then:
 ;templatestyles src="Template:Blockquote/styles.css" / ;"... there is no more rational procedure than the method of trial and error – of conjecture and refutation: of boldly proposing theories; of trying our best to show that these are erroneous; and of accepting them tentatively if our critical efforts are unsuccessful. From the point of view here developed, all laws, all theories, remain essentially tentative, or conjectural, or hypothetical, even when we feel unable to doubt them any longer."
A "bold" hypothesis is a new scientific idea which, if it was true, would be able to predict and/or explain a lot, or a lot more, about the subject being theorized about. The "boldness" of a hypothesis depends mainly on:
Once a bold hypothesis has been mooted, Popper argues, scientists try to investigate and test how well the bold hypothesis can stand up to the known evidence, with the aim of finding counter-arguments which would refute or falsify the bold hypothesis. In this process of testing and criticism, new scientific knowledge is generated. Even if the bold hypothesis turns out to have been wrong, testing it generates new knowledge about what can and cannot be the case. Often it stimulates new research.
Inversely, if a hypothesis lacks the quality of boldness, then it would make very little difference to what scientists already know. It is not "a big deal", i.e. it is not very significant for the theory which exists already. It can contribute rather little to advancing scientific progress, because it does not expand or add to scientific understanding very much.
According to Popper,
 ;templatestyles src="Template:Blockquote/styles.css" / ;"Science does not rest upon solid bedrock. The bold structure of its theories rises, as it were, above a swamp. It is like a building erected on piles. The piles are driven down from above into the swamp, but not down to any natural or ‘given’ base; and if we stop driving the piles deeper, it is not because we have reached firm ground. We simply stop when we are satisfied that the piles are firm enough to carry the structure, at least for the time being." " 
In Popper's philosophy of science, scientific statements are always provisional, they have limits of application, and they could always be wrong. If a statement cannot even in principle be proved wrong, it cannot be a scientific statement. Thus, in Popper's eyes, the falsifiability criterion clearly demarcates "science" from "non-science". This Popperian idea has been very controversial, however. The reason is that it can be quite difficult to test scientifically how true a particular idea is. Even if scientists do "want" to test an idea, they may not know yet "how" exactly to test it conclusively. Yet, scientists also don't want to abandon a hunch that seems useful, simply because they don't know how to verify it yet. This point is especially important for "bold" new hypotheses, because the very "boldness" of the new hypothesis could mean that it would take a lot of work before adequate tests could be designed.
Some philosophers have argued that, in the real world, scientists operate routinely with at least some metaphysical beliefs for which they have no proof or verification whatsoever. According to Paul Feyerabend, the creative processes that lead to a scientific discovery are usually quite reasonable and non-arbitrary. However, the creative processes are by no means fully "rational", and they can be quite unique. Thus, the idea that there is one standard model which can define the rationality of all scientific methods should be rejected.
In one of his later writings, "Objective Knowledge" (1972), Popper argued that:
 ;templatestyles src="Template:Blockquote/styles.css" / ;"A theory is the bolder the greater its content. It is also the riskier: it is the more probable to start with that it will be false. We try to find its weak points, to refute it. If we fail to refute it, or if the refutations we find are at the same time also refutations of the weaker theory which was its predecessor, then we have reason to suspect, or to conjecture, that the stronger theory has no greater falsity content than its weaker predecessor, and, therefore, that it has the greater degree of verisimilitude". 
This interpretation was criticized by Adolf Grünbaum.
Main criticisms.
Popper's idea of the role of bold hypotheses in scientific progress has attracted three main kinds of criticisms.
Despite these important criticisms, Popper's concept of bold hypotheses continues to be widely used in the academic world. One reason is that, at some level, the concept does make sense, even if (arguably) Popper himself failed to define its role in scientific research very well. Another reason is that academic progress always requires that a scholar does something genuinely new and "breaks new ground". If a scholar only concerns themself with tiny, uncontroversial and fairly trivial claims, they are unlikely to be rewarded very much for their effort. Plausible and credible bold hypotheses are highly valued in the academic world, so long as they are reasonably consistent with well-established scientific findings, and do not seriously challenge scientific authority. 
In the business community, too, innovation is very important, to find new ways to reduce costs, increase sales, and increase profits. A bold new idea can be worth a lot of money, and therefore, business people are often sympathetic to bold attempts to reframe what is known already and to create new ideas; without such innovations, they would eventually be defeated by competitors who have a better idea. So the idea of a bold hypothesis also continues to have a place in economics, management theory and business administration.
Notes and references.
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