"We cannot use the Ruling Ring. That we know too well. It belongs to Sauron and was made by him and is altogether evil. Its strength, Boromir, is too great for anyone to wield at will, save only those who have great power of their own. But for them it holds an even deadlier peril. The very desire of it corrupts the heart. Consider Saruman. If any of the Wise should with this Ring overthrow the Lord of Mordor, using his own arts, he would set himself on Sauron's throne, and yet another Dark Lord would appear. And that is another reason why the Ring should be destroyed: as long as it is in the world it will be a danger even to the Wise. For nothing is evil in the beginning. Even Sauron was not so."Patricius' post shed light on the way that Tolkien wrestled with the question of the orcs.
Do also see the post on Tolkien's valedictory address to the university of Oxford.