Science is a way of knowing about the world that depends constantly on free inquiry, experimentation and empiricism. As such, anything that is established in science has credibility based on the methodology used, not on the word of any individual scientist. It is the ability of other scientists to duplicate the experimental results that one of their number publishes that makes a scientific law credible.
Physics and chemistry are the two foundational sciences on which all others, including astronomy, biology, and geology, are based. Unlike the first two, astronomy, biology and geology also have hypotheses and theories that are historical in nature. The basic assumption is that all physical and chemical laws are constant, remaining the same throughout deep time. Thus, any historical hypothesis or theory, to also be scientific, must be in strict conformance with all the known scientific laws that were previously established as valid via the scientific method.
Understanding this, we can consistently apply all known scientific laws to deep time to both test hypotheses and propose them. For example, the Doppler effect was used to discover that most galaxies were moving away from us and in proportion to their distance from our galaxy. This was defined as Hubble’s Law, which in turn led to the Big Bang theory of cosmic origins. Likewise, repeated experimentation on living animals and plants in which artificial selection is done to change the genetic makeup of their populations in a laboratory setting establishes the validity of Darwin’s theory of evolution by natural selection. It stands to reason that if slight changes can be made in populations of organisms in a short period of time, then massive changes indicated by the fossil record should be possible over a long period of time. But to show this may not be possible, we’d have to do additional experiments to attempt to find the limits of genetic and physical change in such a population and thus possibly falsify evolution. Such an experiment was proposed and detailed here:
It is important to understand that it is impossible to have genuine natural history without a scientific basis. Previous attempts to describe the past history of the universe without science are mythology. Mythology has no references whatsoever to physical and chemical laws and usually involve one or more supernatural deities, thus they are not scientific. Any tests of a historical hypothesis or theory involving deep time can never contradict the scientific laws previously established as valid via the scientific method.
So, is evolution a fact? Is the Big Bang theory a fact? Is the theory of continental drift a fact? Only if you accept as valid all the scientific laws that support them. And those laws, in turn, are supported by the scientific method. That is why the concept of “creation science” is a fraud. It is nothing more than an attempt to support mythology by the misuse of scientific terminology.
Since it is obvious that evolution is scientific, and creationism is not, why is there even a controversy over teaching such concepts as “Intelligent Design” in public schools? Because of politics and religion interfering with science education. And this is nonsense if you just follow the chain of reason that was used from the late 19th Century onwards to support evolution.