Question

For what reasons could a theory be changed or replaced?

Answer 1

"A useful theory that has been tested and supported may become a dominant view among the majority of scientists. However, science is always changing. As new evidence is uncovered, a theory may be revised or replaced by a more useful explanation."

Answer 2

When there is ample experimental evidence that suggests the theory cannot make valid predictions or when parts of the theory or incompatible with a more established theory.