When are scientific ideas modified?

a. When a new scientist becomes more famous

b. When there is a change in politics

c. When a new, better idea is developed

d. When people get tired of the old idea

The logical answer is c provided that the "new, better idea" stand up to scrutiny under the scientific method.

Politics (b.) should never be a reason for changing scientific ideas.

Likewise, the fame of a particular scientist should have nothing to do with the modification of a scientific idea.

Science uses the scientific method and whether people are tired of old ideas or not is not a reason to change them.