We just could not find that thesis. But we are confident that cows can t violate the law of conservation of energy, and cannot produce energy out of nothing. Therefore, there must be a limit to how much milk a cow can produce. One could make a similar argument about the egg production of chickens. Other Limits Clearly there are limits to how much an existing characteristic can change.
Horses already know how to run.
Running is an existing characteristic. There is a limit to how much faster they can run. We believe this because there is evidence from the Kentucky Derby that they have reached the limit. But for evolution to be true, there must not only be no limit to existing characteristics, there must also be no limit to the appearance of entirely new characteristics. According to statement 4b, there is no fundamental reason why horses can t grow wings and learn to fly.