What is intelligent ignorance

What other than "bias" or "ignorance" explains why intelligent people (d) believe irrational or stupid things?

You can come to an irrational conclusion for the following reasons:

  1. Ignorance - Knowing this is not enough to draw a conclusion

  2. Bias - emphasis on some things (properties) that are not as dominant as they appear

  3. Mistake - Wrong inferring a conclusion from a premise

  4. Justification by actual knowledge / belief - justification of something as a result of something already believed or known to be true

Example - For a simple syllogism -

  1. If A then B.

  2. A

  3. B.

You can make a mistake on the first or second premise. Either this could be because you don't know of exceptions (ignorance) or because you believe something is true / dominant when it isn't true (bias). Apart from that, you can make an honest mistake or draw a wrong conclusion by justifying what you know or believe to be true from current knowledge / belief.

It is usually a combination of these factors. Note that people used to believe in the miasm theory. You can call it ignorance, but it was partly true. There had to be a reason why people who were otherwise healthy got sick with illness. Since air could be felt but germs could neither be felt nor seen, the guilty party was decided. It was a result of both ignorance and justification by actual knowledge / belief.