The Kuhn Cycle is a simple cycle of progress described by Thomas Kuhn in 1962 in his work The Structure of Scientific Revolutions. In Structure Kuhn challenged the world's current conception of science, which was that it was a steady progression of the accumulation of new ideas.
Kuhn identified a cycle of different stages as our knowledge progresses, from Pre-science to Normal Science and the transformations, rise and fall, crisis and changes in models we made about what we are studying.
This is a short summary:
All new fields begin in Pre-science, where they have begun to focus on a problem area but are not yet capable of solving it or making major advances.
Efforts to provide a model of understanding that works eventually bear fruit. The field can at last make major progress on its central problems. This puts the field in the Normal Science step where it tends to stay longer than any other step.
Over time the field digs so deep into its area of interest it discovers new questions its current model of understanding cannot answer. As more of these anomalies ("violations of expectations") appear the model grows weaker. This is the Model Drift step.
If enough unsolved anomalies appear and the model cannot be patched up to explain them, the Model Crisis step is reached. Here the model is obviously no longer capable of solving the field's current problems of interest. It's a crisis because decisions can no longer be made rationally. Guesswork and intuition must be used instead. These tend to fail.
Finally out of the struggle to form a new model of understanding one or more viable candidates emerge. This begins the Model Revolution step. It's a revolution because the new model is a new paradigm. It's radically different from the old paradigm, so different the two are incommensurate. Each uses its own rules to judge the other. Thus believers in each paradigm cannot communicate well. This causes paradigm change resistance.
Once a single new paradigm is settled on by a few influential supporters, the Paradigm Change step begins. Here the field transitions from the old to the new paradigm while improving the new paradigm to maturity. Eventually the old paradigm is sufficiently replaced and becomes the field's new Normal Science. The cycle then begins all over again, because our knowledge about the world is never complete.