Is natural selection a fact or theory?

It is a fact that organisms can undergo both macro and micro evolution; however, the exact causes of evolution remain unknown.

Because of prevailing debate, natural selection is regarded as a theory rather than a proven explanation for why organisms can evolve, despite being supported by observable evidence.

In the natural world, one can easily witness the effects of natural selection at work. For example, foxes living in the Northern Hemisphere on the edge of the snow line are light grey, while those living within the line have "adapted" to become mostly white. Foxes living in the forest to the south of the snow line are primarily brown.

Another example is how, prior to the industrial revolution, moths in English forests were predominantly white, but during that time, the forest was covered in black residue from burning coal. However, when coal was refined and replaced by natural gas and oil, the black residue in the forest vanished, and the moths returned to being predominantly white.

These examples demonstrate the existence of natural selection, but they do not demonstrate how natural selection can lead to the emergence of new forms that are more complex and "advanced" than their predecessors.

Natural selection is a fact, but it is a component of the widely accepted, albeit unverified, Neo Darwinian Evolution theory.

Natural selection is both a fact and a theory. It is a fact that populations evolve over time, and natural selection is one of the mechanisms driving this evolution. Additionally, natural selection is a scientific theory that explains how species adapt to their environment through the differential survival and reproduction of individuals with advantageous traits.