The individual has a stock of old opinions already. The individual meets a new experience that puts some of these old opinions to a strain. Somebody contradicts them. In a reflective moment, the individual discovers that they contradict each other. The individual hears of facts with which they are incompatible.
Desires arise in the individual which the old opinions fail to satisfy.
The result is inward trouble, to which the individual's mind till then had been a stranger. The individual seeks to escape from this inward trouble by modifying the old opinions. Old opinions resist change very variously. The individual tries to change this and then that. Finally, some new opinion comes up which the individual can graft upon the ancient stock of old opinions with a minimum of disturbance to the others.