Evolution violates the 2nd law of thermodynamics. There are no transitional fossils. The theory of evolution says that life originated, and evolution proceeds, by random chance. Explanations of why these statements are wrong are given below. Evolution has never been observed.
Biologists define evolution as a change in the gene pool of a population over time.
One example is insects developing a resistance to pesticides over the period of a few years. Even most Creationists recognize that evolution at this level is a fact. What they don't appreciate is that this rate of evolution is all that is required to produce the diversity of all living things from a common ancestor. The origin of new species by evolution has also been observed, both in the laboratory and in the wild. Even without these direct observations, it would be wrong to say that evolution hasn't been observed.