When stripped of the excess baggage that has been added to it over the years, Modern Evolution Theory is summed up in the following two sentences:
A genetic population evolves whenever new genetic data is added to that population. New genetic data is added either by cross-breeding or by mutations.
That is really all there is to Modern Evolution Theory. It is nothing more than an explanation of what causes genetic populations to evolve, with the word "evolve" meaning "change".
Modern Evolution Theory is demonstrated to be accurate whenever dog breeders produce a new breed of dog, such as when the monks at the Monastery of Bernard de Menthon cross-bred previously-existing dogs in order to produce the breed of dog call the Saint Bernard.
The accuracy of Modern Evolution Theory is demonstrated by the rise of antibiotic-resistant infections as the result of mutating bacteria.
Regrettably, people are often confused by what is and isn't in Modern Evolution Theory. Here are some examples.
1. Modern Evolution Theory doesn't say that the passage of time causes evolutionary events to take place. Time is a metric, a measurement, not a force.
2. Modern Evolution Theory is about the causes of evolutionary events. It is the Theory of Common Descent that allegedly describes what evolutionary events have taken place. It is
not necessary for one to believe the latter theory in order to believe the former.
3. The Theory of Natural Selection isn't the same thing as Modern Evolution Theory. According to the Theory of Natural Selection, the species best equipped to survive in an environment is the species most likely to live long enough to reproduce. When an environmental change takes place, the species best equipped for the change is the species most likely to survive the change. If a species is ill-equipped for its environment, then that species will most likely die out. In other words, the environment (a.k.a. Nature) selects what species will survive. This is what is meant by "survival of the fittest".
4. Modern Evolution Theory doesn't explain how life began. Hypotheses about abiogenesis attempt to explain how life began.
5. Modern Evolution Theory doesn't require that all mutations be random. British zoologist Richard Dawkins writes, “It is not critical to the theory that mutation
must be random, and it most certainly provides no excuse to tar the whole theory with the brush of randomness.”1
6. Modern Evolution Theory doesn't contradict the Second Law of Thermodynamics. Modern Evolution Theory pertains to living organisms, which are open systems. The Second Law of Thermodynamics pertains to closed systems. Comparing Evolution Theory to the Second Law of Thermodynamics is like comparing apples to oranges.
7. Modern Evolution Theory pertains to the scientific discipline of Biology. The age of the Earth pertains to the scientific discipline of Geology. What Geology says about the age of the Earth is irrelevant to Modern Evolution Theory.
8. What scientists mean by "theory" isn't what non-scientists mean by "theory". Science writer Kim Ann Zimmerman states the following:
"When used in non-scientific context, the word “theory” implies that something is unproven or speculative. As used in science, however, a theory is an explanation or model based on observation, experimentation, and reasoning, especially one that has been tested and confirmed as a general principle helping to explain and predict natural phenomena."2
9. Modern Evolution Theory is mute in regards to the existence of God or the existence of anything that is supernatural.
10. Nothing in Modern Evolution Theory prevents God from directing evolutionary events should such events occur. Nothing in Modern Evolution Theory prevents people from participating in evolutionary events.
For example, the creation of the Saint Bernard breed of dog is an example of an evolutionary event caused by the mixing of genetic data via cross-breeding. That event was brought about by deliberate human action, and it is possible that God inspired that action to take place.
Quote Sources
1 Richard Dawkins,
Climbing Mount Improbable (W.W. Norton & Company: 1996), pp. 80-82.
2 Kim Ann Zimmerman, "What is a Scientific Theory?",
Live Science,
http://www.livescience.com/21491-what-is-a-scientific-theory-definition-of-theory.html