It seems to me that we judge propositions as true or false based on subjective feelings of rightness, and subjective feelings of wrongness.
It seems to me that no distinction can be made between, “I believe that X,” and “I feel that X.” Belief is a feeling that something is right. Disbelief is a feeling that something is wrong.
Thus, for instance, when one reads a math proof, the proof eventually generates in oneself a feeling that its conclusion is right. This feeling of rightness is the “aha!” moment of understanding the proof. If one is studying a standard proof, one probably already believes in its conclusion prior to understanding the proof. But, if one is a mathematician studying a newly published proof, there might be some doubt in one’s mind about the correctness of its conclusion. In this case one would believe in the conclusion only when this “aha!” feeling came.
I suggest that, in this latter case, the feeling is the direct cause of the belief, and the proof is an indirect cause of the belief. The proof generates the feeling, and the feeling generates the belief.
How is it that I first say that the feeling is the belief, and now say instead that the feeling generates the belief? One can draw an analogy to love. When one falls in love with another, there are initial feelings of love. These initial emotions give way to more enduring but less intense feelings of love. The character of this enduring love is different from the initial passion. So it is with belief: there is the initial passion of revelation, and then ongoing feelings of commitment to the proposition believed.
It is tempting to take my conclusion in the following way: “if all of our beliefs are based on our feelings, then everything is subjective, and we can believe whatever we want.” I don’t suggest that. It is my opinion that our feelings of rightness and wrongness are semi-accurate gauges of reality. Sometimes we feel something to be right, and it is actually right. Sometimes we feel something to be wrong, and it is actually wrong. In other cases, of course, these feelings mislead us.
From here on I will use “belief” as a synonym for “feeling of rightness.”
We have already noted that logical validity is a condition which almost always leads to belief. What other conditions lead to belief? I suggest that we are likely to believe something if:
1. it is revealed to us through experience;
2. we have seen solid arguments or evidence for it;
3. it is consistent with other things that we believe;
4. those in our social circles also believe it;
5. it is simple and beautiful;
6. it generates positive emotions in us;
7. it is consistent with our intuitions.
This list is undoubtedly incomplete, and contains some overlap. We can understand all of these items as conditions that usually generate increased feelings of rightness.