The main reason people think a probability of 100% is necessary is that they assume that any other probability implies a subjective feeling of doubt, and they are aware that it is impossible to go through life in a continuous state of subjective doubt about whether or not food is necessary to sustain one’s life and the like.
Once someone has separated the probability from this subjective feeling, a person can see that a subjective feeling of certainty can be justified in many cases, even though the probability is less than 100%. Once this has been admitted, I think most people would not have a problem with admitting that 100% probabilities are not possible.
I would rather say that for normal people certainty is ~90% propability, you can notice this noticing that people who say something is certain aren´t willing to act in ways that would cause serious harm if they were wrong.
The main reason people think a probability of 100% is necessary is that they assume that any other probability implies a subjective feeling of doubt, and they are aware that it is impossible to go through life in a continuous state of subjective doubt about whether or not food is necessary to sustain one’s life and the like.
Once someone has separated the probability from this subjective feeling, a person can see that a subjective feeling of certainty can be justified in many cases, even though the probability is less than 100%. Once this has been admitted, I think most people would not have a problem with admitting that 100% probabilities are not possible.
I would rather say that for normal people certainty is ~90% propability, you can notice this noticing that people who say something is certain aren´t willing to act in ways that would cause serious harm if they were wrong.