According to Free Trait Theory, we are born and culturally endowed with certain personality traits — introversion, for example — but we can and do act out of character in the service of “core personal projects.”
In other words, introverts are capable of acting like extroverts for the sake of work they consider important, people they love, or anything they value highly. Free Trait Theory explains why an introvert might throw his extroverted wife a surprise party or join the PTA at his daughter’s school. It explains how it’s possible for an extroverted scientist to behave with reserve in her laboratory, for an agreeable person to act hard-nosed during a business negotiation, and for a cantankerous uncle to treat his niece tenderly when he takes her out for ice cream.

All of us, when it comes to personality, naturally think in terms of absolutes: that a person is a certain way or is not a certain way. But what Zimbardo and Hartshorne and May are suggesting is that this is a mistake, that when we think only in terms of inherent traits and forget the role of situations, we're deceiving ourselves about the real causes of human behavior.

Schwartz's research suggests something important: we can stretch our personalities, but only up to a point. Our inborn temperaments influence us, regardless of the lives we lead. A sizeable part of who we are is ordained by our genes, by our brains, by our nervous systems. And yet the elasticity that Schwartz found in some of the high-reactive teens also suggests the converse: we have free will and can use it to shape our personalities.

we can stretch our personalities, but only up to a point. Our inborn temperaments influence us, regardless of the lives we lead. A sizable part of who we are is ordained by our genes, by our brains, by our nervous systems. And yet the elasticity that Schwartz found in some of the high-reactive teens also suggests the converse: we have free will and can use it to shape our personalities.
These seem like contradictory principles, but they are not. Free will can take us far, suggests Dr. Schwartz’s research, but it cannot carry us infinitely beyond our genetic limits. Bill Gates is never going to be Bill Clinton, no matter how he polishes his social skills, and Bill Clinton can never be Bill Gates, no matter how much time he spends alone with a computer.
We might call this the “rubber band theory” of personality. We are like rubber bands at rest. We are elastic and can stretch ourselves, but only so much.

The notion that we "have a nature" far from threatening the concept of freedom, is absolutely essential to it. If we were genuinely plastic and indeterminate at birth, there could be no reason why society should not stamp us into any shape that might suit it. The reason people view suggestions about inborn tendencies with such indiscriminate horror seems to be that they think exclusively in one particular way in which the idea of such tendencies has been misused, namely, that where conservative theorists invoke them uncritically to resist reform. But liberal theorists who combat such resistance need them just as much, and indeed, usually more. The early architects of our current notion of freedom made human nature their cornerstone. Rousseau's trumpet call "Man is born free, but everywhere he is in chains," makes sense only as description of our innate constitution as something positive, already determined, and conflicting with what society does to us. Kant and Mill took similar positions. And Marx, though he officially dropped the notion of human nature and attacked the term, relied on the idea as much as anybody else for his crucial notion of Dehumanization.

Introversion- along with its cousins sensitivity, seriousness, and shyness- is now a second-class personality trait, somewhere between a disappointment and a pathology. Introverts living in the Extrovert Ideal are like women in a man's world, discounted because of a trait that goes to the core of who they are. Extroversion is an enormously appealing personality style, but we've turned it into an oppressive standard to which most of us feel we must conform.

The ability to deal with adversity, to accept pain, to be calm under pressure- these are the traits we look for. Some can be taught, much is innate.

I may point out that it would be possible (theoretically if not practically) to analyze a single act of an individual and see in it the expression of his physiological needs, his safety needs, his love needs, his esteem needs and selfactualization. This contrasts sharply with the more naive brand of trait psychology in which one trait or one motive accounts for a certain kind of act, i. e., an aggressive act is traced solely to a trait of aggressiveness.

The ultimate objective test of free will would seem to be: Can one predict the behavior of the organism? If one can, then it clearly doesn't have free will but is predetermined. On the other hand, if one cannot predict the behavior, one could take that as an operational definition that the organism has free will … The real reason why we cannot predict human behavior is that it is just too difficult. We already know the basic physical laws that govern the activity of the brain, and they are comparatively simple. But it is just too hard to solve the equations when there are more than a few particles involved … So although we know the fundamental equations that govern the brain, we are quite unable to use them to predict human behavior. This situation arises in science whenever we deal with the macroscopic system, because the number of particles is always too large for there to be any chance of solving the fundamental equations. What we do instead is use effective theories. These are approximations in which the very large number of particles are replaced by a few quantities. An example is fluid mechanics … I want to suggest that the concept of free will and moral responsibility for our actions are really an effective theory in the sense of fluid mechanics. It may be that everything we do is determined by some grand unified theory. If that theory has determined that we shall die by hanging, then we shall not drown. But you would have to be awfully sure that you were destined for the gallows to put to sea in a small boat during a storm. I have noticed that even people who claim everything is predetermined and that we can do nothing to change it, look before they cross the road. … One cannot base one's conduct on the idea that everything is determined, because one does not know what has been determined. Instead, one has to adopt the effective theory that one has free will and that one is responsible for one's actions. This theory is not very good at predicting human behavior, but we adopt it because there is no chance of solving the equations arising from the fundamental laws. There is also a Darwinian reason that we believe in free will: A society in which the individual feels responsible for his or her actions is more likely to work together and survive to spread its values.

What are the consequences of thinking that your intelligence or personality is something you can develop, as opposed to something that is a fixed, deep-seated trait?

Two distinctive traits especially identify beyond a doubt a strong and dominant character. One trait is contempt for external circumstances, when one is convinced that men ought to respect, to desire, and to pursue only what is moral and right, that men should be subject to nothing, not to another man, not to some disturbing passion, not to Fortune.
The second trait, when your character has the disposition I outlined just now, is to perform the kind of services that are significant and most beneficial; but they should also be services that are a severe challenge, that are filled with ordeals, and that endanger not only your life but also the many comforts that make life attractive.

Of these two traits, all the glory, magnificence, and the advantage, too, let us not forget, are in the second, while the drive and the discipline that make men great are in the former.

The Big Five traits are extroversion, conscientiousness, neuroticism, agreeableness, and openness. Psychologists have devised a series of questionnaires to help you discover how high or low you score on each of these traits — whether, for example, you are extremely extroverted (like George W. Bush), or not so extroverted, or, like most of us, somewhere near the

Much of what we call personality is not a fixed set of traits, only coping mechanisms a person acquired in childhood. (p127)

What are the consequences of thinking that your intelligence or personality is something you can develop, as opposed to something that is a fixed, deep-seated trait? Let’s first look in on the age-old, fiercely waged debate about human nature and then return to the question of what these beliefs mean for you.