The word "evolution" is an umbrella term referring to many things and thus can be a cause of great confusion if not defined correctly in the course of discussion and debate.
The first meaning of "evolution", that living organisms have a built in propensity to adapt and undergo changes, is an observed and undeniable reality.
The environment clearly has an effect on the traits and qualities of living organisms, however, the propensity for change lies within living organisms itself (due to the DNA-gene-cell system).
This type of evolution accounts for variation within the type, however, the true and real source of variation is the in-built propensity to adapt to the environment, living organisms are designed with that in-built feature and ability.
That which is touted as "the fact of evolution" is based upon this observable reality (in-built adaptability within boundaries).
However, an extrapolation is made from this empirical observation, to support a metaphysical belief which has no scientific basis, but is merely a preferred explanation based upon a prior assumption of naturalism.
That metaphysical belief is:
The second and contested meaning of "evolution" which is the "blind watchmaker thesis" popularized by Richard Dawkins in his support of the modern synthesis (natural selection acting upon random mutations).
This meaning of evolution purports that unguided, unintelligent, purposeless, material processes are completely sufficient to account for the "appearance" of design in living organisms and the diversity of life through random mutations in genetic information.
This is a fallacy and is an insult to intelligence. It is a discredited metaphysical belief, an explanation demanded by a prior commitment to materialism and naturalism.
It should be noted that as it stands in current scientific knowledge about the genome and nature of mutations, the modern synthesis (natural selection acting on random mutations as the explanation for all life's diversity) has been proven false and impossible.
In light of this, evolutionary biologists are devising what they call an "extended evolutionary synthesis" to move away from the gene-centric neo-Darwinian view (because they know it is false).
It is impossible to account for life's diversity through random mutations in genes alone, it is probabilistically unfeasible and practically impossible.
>>This has been proven without any shadow of doubt.
Meanwhile, as this is kept hidden from the public, evolutionists are frantically trying to devise a new "synthesis" to explain life's diversity away from gene-centric explanations. In short, there is currently no agreed upon, proven, evolutionary mechanism on the table because the modern synthesis (as an all explanatory mechanism) is proven to be a fallacy.
Despite this the public are misled through smoke and mirrors with the fallacious claim of "natural selection acting on random mutations as an explanation of life's diversity" being a fact.