Popularized by physicist Thomas Kuhn in The Structure of Scientific Revolutions [1], the phrase “paradigm shift” has become quite popular in many fields. It is also somewhat overused when applied to relatively minor modifications of contemporary thought.
Originally referencing the changes in scientific thinking and when applied to societies rather than individuals, the paradigm shift refers to a wholesale restructuring of a body of knowledge. Classical shifts in scientific thinking occurred with the transition from alchemy as a mechanism for understanding the physical world to classical Newtonian physics to relativistic physics to quantum mechanics, and so on.
As Kuhn points out, many very able scientists at each transition were simply unable to make this change. These transitions also and often took years or decades to work their way into the social and intellectual ecosystems they would so fundamentally change. In some cases, really smart scientists simply couldn’t understand the change because it conflicted so radically with their existing beliefs [2]. In other cases, they intellectually understood the change, but could not integrate it and so used the Parking-Lot, the Bolt-on or even the Denial-Rejection approach.
In practice and in both societies and individuals, the true paradigm shift is probably quite rare.
While profound transitions have been recorded in people’s thinking and behavior, resulting in quite different understanding and behavior following the change, they are usually a result of intense experiences.
Example: The body of religious writings has many examples of these profound changes. From the Gautama Buddha to Sister (later Mother, later Saint) Teresa on a train in India in 1946, people have experienced something that has radically changed the course of their life, what they think is important, and how they view and act in the world.
FOOTNOTES
[1] Kuhn, Thomas S. (1962: 1st ed.). The Structure of Scientific Revolutions. University of Chicago Press
[2] As mentioned earlier, this is usually because the old paradigm had become the scientists' way of thinking and the "body of knowledge" possessed by people in the same discipline had favored them so well and had become ingrained.