A thought experiment

Is it possible for someone to change their personality overnight?

At least outwardly. And once the outward change is completely manifested over a period of time, will this gradually lead to an equivalent change inwardly as well?

Especially if that someone has entered into the latter half of his twenties?

This is a thought experiment being conducted to ascertain the feasibility of such a theory.

A precognition required for this discussion is the concept of inner and outer personalities, one which is apparent to the outside world and one which is apparent only to the individual.

Let us start by assuming that it is not possible to do so.
It is not possible for someone to change his or her personality once they are well into their adulthood.

This means that this person will display the same set of different reactions to various stimuli consistently according to the dictates of his conscious personality.

Ergo, the person's reactions can be predicted to an accurate degree by keen observation during the application of a same set of stimuli under different circumstances.

But, the one thing that nature has taught us and which has been proved by considerable empirical evidence is that the behaviour of men is highly stochastic.

This means that there is a part of the behaviour which is known, predictable and easily explainable. But there is another, quite substantial part, which cannot be understood and thus predicted or explained.

This is especially true in times of extreme stress or under those rare but unavoidable circumstances when the rational brain is bypassed by the amygdala to achieve quick, instinctive responses.

Thus, an apparent paradox comes into being which can only be resolved by recognizing that our initial assumption is untrue.

Thus, it is possible for a person to change his or her personality even at an age when conventional wisdom states that the personality is more or less reaching a state of stasis.

As to what proportion of outward personality can be changed vis-à-vis the inward personality is still unclear and may require further discussion by people more erudite than myself.

As to the possible application of the conclusion derived above, that is something I plan to adopt in the following days.

Whether the attempt is successful ergo proving my hypothesis is something left to the people in my coterie to ascertain.

I can only hope that it is so.

Note : The desirability of the application of the result of this thought experiment to society is something which is not included in the scope of this discussion.