When considering whether natural organisms have been designed, or alternatively have come to be the way they are through natural processes, it's a good idea to consider some examples.
Look at Mount Rushmore in South Dakota. One can recognise faces carved into the mountainside, three-dimensional images of not just generic people, but specific men who actually lived — and these are their likenesses. We know, however, that these examples are not naturally occurring phenomena; they came into existence by the action of designing minds.
When we look at the forms taken by living organisms we see similar arrangements of parts, but to a much greater degree. Life is extremely complex — so complex, in fact, that to imagine that a designing mind could accurately specify such complexity is stretching credulity beyond reasonable limits. We simply cannot imagine any mind being sufficiently intelligent to be capable of such vast complexity. Even if such a complex designing mind was responsible for the complexity of life, one would be remiss in omitting to enquire where the complexity of the designer originated.
In the absence of any other explanation, therefore, we must by default assume that such complexity has arisen by gradual stepwise refinement of regressively simpler organisms. Such small steps seem intuitively more likely than the sudden fait accompli of a grand design.
Extrapolating these small steps backwards in time it seems obvious, therefore, that life originally began very simply, probably by random emergence of self-replicating molecules. It seems likely that in the not too distant future this mechanism will be demonstrated in the laboratory.
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