why is evolutionary theory constantly changing?

The reason that the theory of evolution keeps changing is that it is trying to cope with all the new facts as they emerge.
As some proponent of evolution say, 'evolution is the fact, how it works is the theory'. I think the sad part about the whole evolution farce is that people often think that an intelligent scientist has no reason to obscure the facts. But if evolution were falsified the results to the establishment would be unthinkable. So they keep repairing their littel ideological ship till a better one comes along that doesn't have intelligent design written on it.