Scientific discovery is a creative process that generates new knowledge and reconceptualizes previous knowledge. Discoveries happen at all stages of science, but are most likely to occur during times of paradigm crisis or in pre-paradigmatic periods. In these periods, scientists speculate and develop tentative theories, generating novel expectations for experiments and observations. These lead to the articulation of new phenomena and their specification in experimental results, which in turn lead to new ideas that clarify previous ideas and make them more exact. This back and forth between the initial conception of a new idea (a happy thought) and its subsequent articulation and specification is known as scientific discovery.
The demarcation criterion for what constitutes scientific discovery is not a simple one. Philosophers differ on whether the process of conceiving a new theory is part of discovery, and if so, what rules can be used to guide it. Philosophers also disagree on what exactly it means to have a “happy thought” and on whether the process of having such an insight can be considered a scientific logical process.
In light of these disagreements, some philosophers have sought to separate the different elements of scientific discovery and explore them independently. The most common approach is to impose a distinction between different justification procedures, with consequential or strong justification methods applying to the process of testing a hypothesis, and generative or weak evaluations being appropriate to the initial conception of a new idea.