When an individual is described as behaving out of character, typically what is meant is that the person in question is acting in such a way that appears to conflict with or contradict their established personality traits. For instance, suppose that a diligent student begins skipping classes, and that her grades drop precipitously; most would agree that, in that case, the student is acting out of accordance with her usual character. Is that actually true? Though it may break from what one would usually expect her to do, I claim that she is still behaving within the bounds of her character, as there is undoubtedly some reason both valid and compelling to her that explains this change. Perhaps someone close to her passed away, or perhaps she contracted some illness or began suffering from a disorder, or perhaps she decided that the degree she would receive from the university was not worth the swathes of time and effort necessary to earn it. The exact reason is not important; note instead that it is not the student who changed, but rather the paradigm in which she is operating. Put another way, the student is not acting out of character, but instead behaves differently due to a shift in her life situation.
To extend this idea further, consider that this holds true in all cases. That is, no one ever thinks or feels in a manner inconsistent with who they are, as said thoughts and feelings are reasonable and justified based upon both the individual’s personality and the circumstances – or, at least, the individual’s perception and understanding of the circumstances, however accurate or inaccurate that may be – in which they occurred. From this, we can conclude that it is actually impossible for someone to behave outside of their character; everything that a person does depends upon their character traits and their experiences up to the present, so anything that they choose to do will always fall within the set of potential actions that that person might do. That is, for an individual, there exists a set of possible actions that said individual might perform, and the contents of this set fluctuate constantly based upon alterations in the individual’s personality – which will very nearly always be incremental or gradual – and all additional experiences gained by the individual. Thus, the set of actions that, say, our ailing student might undertake at one particular moment will differ to some extent in the next, with the difference depending on how far apart these moments are and what happened to or around our student in that intervening span.
It might seem questionable to assert that all of an individual’s actions can be grouped into a set. After all, one might say, a person is capable of doing anything whenever they want. They could go and murder all of their loved ones, or go to work wearing all of their clothes inside out, or punch their superiors in the solar plexus; a person has free will, and can follow whatever course of action they want at any time, so attempting to establish some boundary for a person’s actions is absurd. I agree that this is hypothetically true, as there is nothing physically preventing me, for instance, from taking my laptop up to the top floor of a building and throwing it down at the passerby below me. I would not do that, however, unless I had a thoroughly compelling reason, and I would argue that no one would kill those dear to them or assault another individual without some equally galvanizing motivation. Indeed, when law enforcement agents are profiling a criminal, they seek among other things to identify the perpetrator’s motive, as they would not have committed the crime were they lacking some underlying justification for their actions. To rephrase this, an individual indeed has the capacity for an inordinate amount of colorful and atypical behaviors, but the individual would not choose to do those things unless they had a reason to do so. These motivating factors are the consequences of personality traits, thoughts and feelings, and circumstances. That is, the individual only chooses to take these particular actions when it is within their character to do so according to their personality and the current situation.
Given that this is the case, we could conceivably construct a formula to predict a person’s actions. That is, if one knew an individual’s personality, their current mental state, and their current circumstances, then one could produce a mathematical procedure that, when the above data are fed into it as inputs, would determine what action the individual would take. Of course, this notion assumes unrealistically that a mathematically precise notation would exist to represent said data. How can one model something as nebulous and abstract as a personality? That question still stands even if one were to attempt to boil down personality into some combination of genetics and experiences; though a gene sequence is simply a string of chemicals, experiences comprise not only multifaceted sensory inputs, but also emotional contexts and sequences of trains of thoughts among other things. As such, it is safe to say that, for the foreseeable future, no such algorithm could actually be created. Be that as it may, I argue that the theoretical existence of this formula is still conceptually valid. To restate it, should an individual’s personality, mental state, and circumstances be known and understood, an accurate estimation of how they will behave could be made, as those three parameters specify a detailed set of actions that the individual may take.
This claim that human behavior is deterministic may seem ridiculous. One might say, once someone sees what this formula predicts they will do, they can simply do something else, thereby making its prediction wrong. My response to that is that an awareness of the formula’s prediction would qualify as a change in the person’s mental state and circumstances, thus invalidating the output of the formula that they had seen. That is, the results would be out of date as soon as the individual in question became aware of them, as they might be inclined to behave differently out of spite; hypothetically, that spiteful response could also be guessed should the computation be performed again afterward, outside of the individual’s knowledge.