In class on Sunday, the teacher mentioned the necessary and sufficient conditions. It is said that many people can't tell what is a sufficient condition and what is a necessary condition, and often make basic logical mistakes. Actually, sometimes I can't tell the difference. If I discuss theoretical concepts, I may be very clear, but I may be confused when I encounter specific things.
(1) Look at the concept first.
Suppose a is a condition and b is a conclusion.
(1) If B can be deduced from A and A can be deduced from B, then A is a necessary and sufficient condition for B, and in this case, B is also a necessary and sufficient condition for A..
(2) If B can be deduced from A and A cannot be deduced from B, A is a sufficient condition for B, but not a necessary condition.
(3) B cannot be derived from A, A can be derived from B, or it can be said that there is no B without A, then A is a necessary condition for B, but not a sufficient condition.
(4) Of course, there is a fourth case, that is, A can't derive B, and B can't derive A, so A is neither a sufficient condition nor a necessary condition for B, and vice versa, it may be only one of the conditions in some cases or a certain degree of correlation, and there is no fixed inevitable connection.
(2) The following examples illustrate.
(1) Necessary and Sufficient Conditions
Necessary and sufficient conditions are the most stringent conditions. I often met them when I was studying mathematics in middle school. For example, "three sides of a triangle are equal" and "triangle is equal" are necessary and sufficient conditions for each other.
Freud said that it is a necessary and sufficient condition for mental health in the future to spend every stage of the development of "sexual psychology" (oral desire period, anal desire period and reproductive period) (Basic Knowledge of Psychological Counselors, p298). In terms of development, these three stages are reasonably spent, and then they are psychologically healthy; If a person is mentally healthy, you can know that he has passed these three stages reasonably.
This seems to be right, but it seems to be wrong, a bit absolute. First of all, what does "reasonable consumption" mean? There seems to be no clear standard unless there are obvious events. In addition, if you spend every stage reasonably, will you be mentally healthy when you grow up? Not necessarily? On the other hand, did a mentally healthy adult really go through these three stages reasonably when he was a child? Perhaps Freud's statement about sufficiency and necessity is not quite what we understand. A little confused.
(2) Sufficient conditions
The sufficient condition is that this condition is enough and things will happen. In our daily life, we often use "if … then …" and "as long as …", which are generally sufficient conditions. For example, if it rains, the ground will become very wet; As long as this game can be won, China Men's Football Team can qualify. But fullness is not necessarily necessary. Wet ground is not necessarily rain, but water spilled by sprinkler; China men's soccer team can qualify, and it is not necessary to win this game. Winning other games may also qualify.
For example, the generalization mentioned a few days ago, if the symptoms of a mentally unhealthy person are generalized, then he is a serious psychological problem rather than a general psychological problem, and generalization is a sufficient condition for diagnosing serious psychological problems. So is this a necessary condition? I don't think so, because the reasons for the diagnosis may also be that the symptoms appear for a long time, the psychological conflict is serious, the heart is very painful, and the social function is greatly affected.
(3) Necessary conditions
Necessary conditions refer to several necessary conditions that may be needed to complete something, each of which is necessary, but not necessarily sufficient. The relationship between "someone has violated the law" and "punished according to criminal law" is a necessary condition, but not a sufficient condition. The law violated may also be civil law, which cannot be judged by criminal law. On the other hand, if "punished according to criminal law", it can be inferred that "someone has violated the law".
In psychological counseling, "visitors are willing to change themselves" is a necessary condition for "successful psychological counseling", but it is not a sufficient condition. It also depends on the methods and methods of psychological counselors, the level of professional skills, the specific problems of visitors, favorable weather and location. Similarly, in turn, "successful psychological counseling" can infer that "visitors are willing to change themselves."
(4) It may be just one of the common situations or related to a certain extent.
More often, in psychological counseling, the conditions we think may be just one of the common conditions that produce results, not even conditions, but "connections", which are related to one side or one point of things. For example, people with depression are more likely to "commit suicide" than ordinary people, which means there is a "correlation" between them, but there is no fixed relationship between depression and suicide. First of all, it is not a sufficient condition, because if you don't get depression, you will commit suicide; Of course, it is not a necessary condition. People who commit suicide do not necessarily suffer from depression.
Ellis's ABC theory is about people's unreasonable beliefs, which is caused by the vague understanding of these two conditions. For example, absolute requirements: I love you so much, and you must love me very much. People who have this idea don't realize that there is no sufficient conditional relationship between "I love you" and "You love me". At best, it is only "relevant", and even in many cases it is not even relevant. Don't we often say this: I love you is my business, not yours, and love is a personal business?
This phenomenon can also be seen in extremely bad unreasonable beliefs. For example, if a child goes to junior high school and fails in the mid-term exam, his parents will be anxious and say, If you don't study hard in junior high school, you won't get into a good high school, you won't get into a good university, you won't find a good job, you won't find a good partner, you won't get into a good high school, you won't get into a good university, you won't find a good job, and then your life will be over. The terrible thing is to think of the result as catastrophic step by step. But, calm down and think about it. Did you fail the exam? Does it have anything to do with the following? However, some parents are like this. In fact, they reflect their anxiety. Understanding two almost unrelated things as sufficient conditions will add countless troubles to themselves and bring great pressure to children. Psychological problems often arise in this way.
Many people think that "being rich" means "being very happy", but it is obviously unreasonable to take "being rich" as a sufficient condition for "being very happy". They are related, but there is no fixed connection, which is neither a sufficient condition nor a necessary condition.
It is very important for mental health to understand the principles of necessary conditions and sufficient conditions and distinguish their definitions and differences. It is even more important for a psychological counselor.
Having said that, logic is a bit brain-burning. Another dead end? Ha ha.