The moon is full of rain and shine, and people are doomed. A person may or may not die tomorrow. It is difficult to predict that both possibilities may happen. Since it is difficult to predict, we think they are like two sides of a coin, with a probability of 50%, so the probability that a person may die tomorrow is 50%. By extension, 50% of the people in the world will die tomorrow, and half of them will die.

But is this really the case? Life and death are not two sides of the same coin, and one's life can't be decided like flipping a coin!

The average number of days people live in the world should be more than 20 thousand days, and they will get old one day, so the probability of dying tomorrow is less than one in ten thousand.

This is the mistake of the principle of neutrality. What is the principle of neutrality? That is, when people can't confirm or deny whether something happens, it may or may not happen, and the probability is 50/50. If we use this principle without thinking, we will get many fallacious conclusions.

Pascal, a famous mathematician and physicist dating back to17th century, said: If you are not sure whether the teachings of the church are true or not, flip a coin to solve it. However, if you believe in doctrine, it doesn't matter if the doctrine is false; If the doctrine is true, then go to heaven and enjoy happiness. If you don't believe it, it doesn't matter if the doctrine is false, because you don't believe it yourself; If the doctrine is true, it may fall into hell. In this way, if you make a bet, it is more advantageous to choose the side that believes in the doctrine, isn't it?

By extension, there are so many major religions in the world. If we use this principle to reason for each religion, which religion should we believe in?

There is a cube in the box. We can't see it. Its side length is between 2 meters and 5 meters, assuming it is 4 meters.

The volume of this cube is between 8 and 125. Let's assume that it is 80.

But the volume of a cube with a length of 4 is 64, not 80.

Many facts show that it is incorrect to assume that all possibilities are equal when one thing is uncertain. Why is the probability of a coin turning upside down 50%? This is because coins are flat. The dice are also unified. Provided that the dice are even.

Why many gossips in life are believed by everyone is related to the abuse of the principle of neutrality. When we are uncertain about something, we assume it exists and it goes around. . . I can't help it . It can be seen that sometimes rationality is more important.

So how to solve these problems? Sampling survey is one of the solutions. Deducing the overall probability from experimental data is statistical inference.