 Whether or not particular biological phenomena are designed, they are frequently enough design-like to make design language not only fit living systems extraordinarily well, but to undergird generation of fruitful theoretical conceptions as  well.[4]  Advocates of design arguments claim that the reason why theorizing as if organisms are designed meets with such success is that organisms are in fact designed. Those opposed would say that all teleological concepts in biology must, in one way or another, be reduced to natural selection.