As I recall, the JWs explained it thusly: god created man and woman as perfect creatures. Perfection meant that they had full control of their thoughts and actions; if they wanted to follow god's orders, they could do so without succumbing to temptation out of some fleshly weakness. So when they ate from the fruit they were performing a willful act. At that point they became imperfect, and passed that imperfection to their offspring. Since god had declared his creation "good" it meant that he couldn't just wipe everything out and start over. He had to prove that mankind could be redeemed.
But first there had to be a lengthy period during which imperfect humans filled the Earth and made a mess of it (as imperfect humans were doomed to do). With that experience clearly in mind, once god cleaned up the mess and returned humanity to perfection, no one would want to perform evil acts. And with the question of sovereignty settled, even if someone did decide to turn against god, there was justification for removing that person immediately and not starting the whole mess all over again. Presumably the few people who would falter would be easily made up by new births of perfect humans, and things would be just peachy from then on.
But first there had to be a lengthy period during which imperfect humans filled the Earth and made a mess of it (as imperfect humans were doomed to do). With that experience clearly in mind, once god cleaned up the mess and returned humanity to perfection, no one would want to perform evil acts. And with the question of sovereignty settled, even if someone did decide to turn against god, there was justification for removing that person immediately and not starting the whole mess all over again. Presumably the few people who would falter would be easily made up by new births of perfect humans, and things would be just peachy from then on.
"Well, evolution is a theory. It is also a fact. And facts and theories are different things, not rungs in a hierarchy of increasing certainty. Facts are the world's data. Theories are structures of ideas that explain and interpret facts. Facts don't go away when scientists debate rival theories to explain them. Einstein's theory of gravitation replaced Newton's in this century, but apples didn't suspend themselves in midair, pending the outcome. And humans evolved from ape- like ancestors whether they did so by Darwin's proposed mechanism or by some other yet to be discovered."
-Stephen Jay Gould
-Stephen Jay Gould