Which, of course, it is not.
The fact remains, however, that while evolution should cover the gradual changes of a species, it should not try to explain the origins of life.
If science is going to operate under the assumption that only what is provable IS science, it cannot prove that life originated by 'accident'.
Ah Captain Obvious strikes again ;^)
Sorry, couldn't resist but that the Theory of Evolution doesn't cover the origins of life is what we tell the creationists at least a dozen times per thread but somehow it just doesn't sink in.
In more general terms the ToE is only concerned with the dynamics of populations of self-replicating entities. How these entities arose doesn't matter because it doesn't affect the dynamics of this system in the least. So as long as there are imperfect self-replicators, you have evolution.
If science is going to operate under the assumption that only what is provable IS science, it cannot prove that life originated by 'accident'.
Well, science certainly does operate under the assumption that only what is observable (proof is for mathematics and whisky) is indeed science. However, observable doesn't mean only directly observable but also indirectly. If it were only the former, science would have stopped before it really took off.
Returning to your example, science can indeed not prove that life originated by 'accident', what it can demonstrate however, is that life could have arisen naturally under the right conditions.
Now, this doesn't prove that creationism is false only that it need not necessarily be true (as far as the origin of life is concerned).