Why is evolution considered fact if it is based on a theory?
I am not going to pretend to be an expert linguist, however I do find that before engaging in any dialogue the definition of the key terms should be agreed upon by the message sender and the receiver for clarification purposes. The key words are fact, evolution, and theory in no particular order. I like to tell my friends to have a good conversation we have to be on the same page in the same book. therefore, I have provided the definitions from the Merriam-Webster on line dictionary to assist with response that I will provide.
Definition of Fact:
: a thing done: as aobsolete : feat b: crime <accessory after the fact> carchaic : action 2archaic : performance , doing3:the quality of being actual : actuality <a question of fact hinges on evidence>4 a: something that has actual existence <space exploration is now a fact> b: an actual occurrence <prove the fact of damage>5: a piece of information presented as having objective reality
— in fact : in truth
Definition of Theory:
Etymology: Late Latin theoria, from Greek theōria, from theōrein Date: 1592 1: the analysis of a set of facts in their relation to one another2: abstract thought : speculation3: the general or abstract principles of a body of fact, a science, or an art <music theory>4 a: a belief, policy, or procedure proposed or followed as the basis of action <her method is based on the theory that all children want to learn> b: an ideal or hypothetical set of facts, principles, or circumstances —often used in the phrase in theory<in theory, we have always advocated freedom for all>5: a plausible or scientifically acceptable general principle or body of principles offered to explain phenomena <the wave theory of light>6 a: a hypothesis assumed for the sake of argument or investigation b: an unproved assumption : conjecture c: a body of theorems presenting a concise systematic view of a subject <theory of equations>
Definition of evolution:
1 : a process of change in a certain direction <tumor evolutionand progression -- I. J. Fidler et al> 2 a : the historical development of a biological group (as a race or species) : PHYLOGENY b : a theory that the various types of animals and plants have their origin in other preexisting types and that the distinguishable differences are due to modifications in successive generations - evo·lu·tion·ari·ly/-sh-ner--l/ adverb - evo·lu·tion·ary/-sh-ner-/ adjective
Due to the definition of evolution provided by the academic and scientific community many people would perceive human evolution as a fact. We can see the changes in ourselves from birth, youth, adult old age and death. That is the human life cycle and it applies to all of us. The scientific community tell us that the cells in our body change every seven years.
The answer to the question that I will provide is if a person reviews the biological and historical trends that have occurred on this planet with an analytical approach using scientific thoery, the person is very likely to observe that physically and mentally the "human" species have changed in a particular direction.
Change is an absolute fact. Evolution is considered a fact because in the definition the word change is a key component.