The suffering that exists in the world comes in two kinds: moral evil and natural evil. Moral evil is suffering caused by the actions of others (e.g., murder, rape, war, etc.) Natural evil is suffering which comes about by natural means (e.g., disease, earthquakes, volcanoes, etc.)
So why does evil exists? The most common response to the question about moral evil is the Free Will Defense. It goes something like this: Moral evil exists because it is impossible to have free will without admitting the possibility of doing evil (i.e., misuse of one’s free will.) Because free will has such value God permits the moral evil that results from misuse as an unfortunate byproduct of this great good.
But two smart philosopher friends of mine Kurt Liebegott (Keystone) and Mickey Lorkowski (Akron) brought to my attention a few years ago a clever response to the Free Will Defense. (I do not know where this objection originates.) It goes something like this: The ability to do evil is not required for free will. God could grant free will to his creatures by giving them the ability to choose only from among a range of greater or lesser good options. All choices are constrained. We do not have unlimited free choice. All that is required for real freedom is the ability to choose from among a range of options. God could grant this freedom without making any of the options evil. Take a simple example, God could grant everyone the ability to give to charity either $100 or $1,000 or $10,000this is a legitimate choice and some are morally better than others, but none are choices to do evil. Thus, granting real free will does not require permitting evil choices.
This is a clever argument and I think it succeeds in showing that free will per se does not require the option to do evil. It is possible to grant legitimately free choices among only good options. Nevertheless, I think that the Free Will Defense can be fixed by changing free will to morally significant free will. The good that God wants on this view is a legitimate choice between good and evil. Allowing this choice does, obviously, allow for the possibility of moral evil. Morally significant free will makes us truly responsible for one another in ways that only-good-options free will does not. Now there are varying levels of moral significance. God did not grant his creatures the ability to choose to destroy the whole cosmos, for example. He granted us the option to do only some goods and only some evils. So on this modified account God wanted to impart only a particular level and type of moral significance to the choices of his human creatures.