How consistent is a normal, adult human being from one situation to the next? What causes inconsistencies, if there are any?

Humans’ consistency is dependent on their personality. (Jungian typology comes to mind, especially the dimension added since his time—the “Perceiving” versus “Judging” aspect [in, e.g., the MBTI], which is in Socionics “Irrational” versus “Rational” behavior). Not to seem to dodge the question, most adult humans are fairly consistent from one situation to the next. The relatively healthy personality (and most are) is generally consistent. An incomplete decision, or a conviction loosely held, may render inconsistencies in a personality. Also, persons may perform erratically who believe it is in their best interests to “fight the system,” or to be unpredictable. (The caveat is, of course, most of these are or eventually become “predictably unpredictable.”) Ultimately, a person who is genuinely inconsistent (and not misunderstood of intention or misrepresented in the observer’s mind) has probably a loose grasp on his or her concept of self and that which makes him or her the person that s/he is or has decided to suddenly change.

What does a person have to do or be in order for you to believe that he or she is abnormal, sick, or crazy?

First, the person must perform behaviors that are consistently wild: that is, there is no conceivable (or, at least, benevolent) pattern or end goal in the behavior pattern of the individual. Also, he or she must be ultimately unadaptive to the reality the rest of us share in such a way that it harms—emotionally or physically—the persons with whom he or she is in close contact. Finally, if the individual cannot be made to understand the logic of a simple fact or idea (like a syllogism) or, by extension, that the mode of behavior in which he or she is presently engaging is detrimental to his or her health/safety and that of those around him or her, I would call that person ill or acting abnormally. (This, in addition to the converse of the above-defined “normal behavior”.)

How consistent is a normal, adult human being from one situation to the next? What causes inconsistencies, if there are any?

Humans’ consistency is dependent on their personality. (Jungian typology comes to mind, especially the dimension added since his time—the “Perceiving” versus “Judging” aspect [in, e.g., the MBTI], which is in Socionics “Irrational” versus “Rational” behavior). Not to seem to dodge the question, most adult humans are fairly consistent from one situation to the next. The relatively healthy personality (and most are) is generally consistent. An incomplete decision, or a conviction loosely held, may render inconsistencies in a personality. Also, persons may perform erratically who believe it is in their best interests to “fight the system,” or to be unpredictable. (The caveat is, of course, most of these are or eventually become “predictably unpredictable.”) Ultimately, a person who is genuinely inconsistent (and not misunderstood of intention or misrepresented in the observer’s mind) has probably a loose grasp on his or her concept of self and that which makes him or her the person that s/he is or has decided to suddenly change.

What does a person have to do or be in order for you to believe that he or she is abnormal, sick, or crazy?

First, the person must perform behaviors that are consistently wild: that is, there is no conceivable (or, at least, benevolent) pattern or end goal in the behavior pattern of the individual. Also, he or she must be ultimately unadaptive to the reality the rest of us share in such a way that it harms—emotionally or physically—the persons with whom he or she is in close contact. Finally, if the individual cannot be made to understand the logic of a simple fact or idea (like a syllogism) or, by extension, that the mode of behavior in which he or she is presently engaging is detrimental to his or her health/safety and that of those around him or her, I would call that person ill or acting abnormally. (This, in addition to the converse of the above-defined “normal behavior”.)