A scientific theory is a well-established and tested explanation of natural phenomena that can be used to make predictions about similar phenomena. In order for a proposed explanation to be considered a scientific theory, it must meet certain criteria.

Empirical Evidence
A scientific theory must be supported by empirical evidence, which means that it must be based on observations and experiments that can be repeated and verified by others. This evidence should provide strong support for the theory, but it should also leave room for further testing and refinement.

Consistency with Existing Knowledge
A scientific theory must be consistent with existing knowledge in the relevant field. It should not contradict well-established principles or theories without providing compelling evidence to the contrary.

Falsifiability
A scientific theory must be falsifiable, which means that it can be tested and potentially proven false through observation or experimentation. This does not mean that the theory is necessarily false, but rather that it is subject to testing and can potentially be refined or replaced if new evidence emerges.

Predictive Power
A scientific theory should have predictive power, meaning that it can make accurate predictions about future observations or experiments. These predictions should be testable and verifiable, allowing scientists to evaluate the accuracy of the theory over time.

Example:
One example of a scientific theory is evolution by natural selection. This theory is supported by extensive empirical evidence from a variety of fields such as genetics, paleontology, and ecology. It is also consistent with existing knowledge in these fields and has been shown to have strong predictive power in predicting the distribution of species across geographic regions.

In summary, a scientific theory requires empirical evidence, consistency with existing knowledge, falsifiability, and predictive power in order to be considered a well-established explanation of natural phenomena. These criteria ensure that scientific theories are based on sound evidence and can be tested and refined over time, leading to a deeper understanding of the natural world.