When people try to say to me that evolution is only a theory and creationism is just as valid, I say to them; well let's say you want to work in animal or plant biology producing vaccines or some other up to the minute technology, if you wish to actually achieve anything you will need to work with the principles of evolutionary theory because these principles are the ones that actually work. And so using the old addage that if it looks like a duck, flys like a duck, and waddles like a duck, then it is a pretty good chance it's a duck. So if you have to use evolution and evolution is what works in the job then you had better start considering evolution as being what is real.