What is an essential quality of 'Normal Science' according to Kuhn?

The essential quality of 'Normal Science' according to Kuhn is that it is based on established paradigms. In Kuhn's framework, normal science operates within the confines of a paradigm—a set of shared assumptions, theories, and methods that a scientific community accepts as valid. These paradigms guide research, dictate the types of questions asked, and shape the interpretation of results.

During periods of normal science, researchers work to explore and expand upon the existing knowledge established by these paradigms, aiming for puzzle-solving rather than questioning the foundational principles. This means that the scientific work is cohesive and systematic, aligning with the prevailing theories and standards of practice, rather than chaotic or disorganized.

While the other options mention aspects related to scientific practice, they do not capture the defining nature of normal science as aptly as the focus on established paradigms. For instance, while normal science can involve rigorous methods, it does not fundamentally rely on the scientific method itself as a distinguishing feature. Instead, the reliance on established paradigms is what characterizes this phase of scientific practice, as it defines how scientists operate within a framework that is largely agreed upon by the community.