The term “theory” is something of a misnomer, if the word is taken in its everyday sense of “speculation” or “conjecture” or even “guess”. In science, a theory is an explanatory model that may well be confirmed by overwhelming evidence. Scientists use the word “hypothesis” for a more conjectural idea that stands in need of testing, but the theory of evolution is not a mere hypothesis.
There is now evidential support, from many fields, for a scientific model that explains the diversity of life on Earth as the outcome of biological evolution. New forms have developed, over millions of years, through purely naturalistic mechanisms that prominently include the processes of natural selection described by Darwin (though there is also room for such things as random “genetic drift” and the effects of one-off catastrophic events, such as Earth’s encounter with a small asteroid some 65 million years ago).
All the evidence coheres powerfully to demonstrate the essential truth of the evolutionary model. For example, we can trace the evolution of particular forms of life, date the age of the Earth and the Sun, and correlate the required ages of particular fossilised organisms to the ages of independently-dated rock strata. There is an enormous, and constantly growing, amount of data. It all adds up to the same story, and new observations from all fields of science invariably slot into the “right” places in the evolutionary narrative.
Indeed, the “theory” of evolution, the overall Darwinian model, is now so well-confirmed, by so much data, that it has become inconceivable that its essentials could be wrong. Think how surprising it would be if it turned out that the Sun revolves around the Earth, after all. That’s the level of certainty we are talking about; if the theory of evolution were not essentially correct, it would be as surprising as that to scientists who understand the data.
Posted: June 12th 2007
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