"There seems to me to be only one defense [against the argument from evil] that has any hope of succeeding, and that is the so-called free-will defense: 

God made the world and it was very good. An indispensable part of its goodness was the existence of rational beings: self-aware beings capable of abstract thought and love and having the power of free choice between contemplated alternative courses of action. This last feature of rational beings, free choice or free will, is a good. But even an omnipotent being is unable to control the exercise of free choice, for a choice that was controlled would ...  not be free. In other words, if I have a free choice between x and y, even God cannot ensure that I choose x. To ask God to give me a free choice between x and y and to see to it that I choose x instead of y is to ask God to bring about the intrinsically impossible; it is like asking him to create a round square or a material body with no shape. Having this power of free choice, some or all human beings misused it and produced a certain amount of evil. But free will is a sufficiently great good that its existence outweighs the evils that have resulted and will result from its abuse; and God foresaw this.”

- van Inwagen, The Problem of Evil

“if God has made men such that in their free choices they sometimes prefer what is good and sometimes what is evil, why could he not have made men such that they always freely choose the good? If there is no logical impossibility in a man's freely choosing the good on one, or several occasions, there cannot be a logical impossibility in his freely choosing the good on every occasion. God was not, then, faced with a choice between making innocent automata and making beings who, in acting freely, would sometimes go wrong: there was open to him the obviously better possibility of making beings who would act freely but always go right.”

- Mackie, "Evil and omnipotence"

"It is good that the free choices of humans should include genuine responsibility for other humans, and that involves the opportunity to benefit or harm them. ... A world in which agents can benefit each other but not do each other harm is one where they have only very limited responsibility for each other. ... A God who gave agents only such limited responsibilities ... would have reserved for himself the all important choice of the kind of world it was to be, while simply allowing humans the minor choice of filling in the details."

- Swinburne, "The problem of evil"

"Suppose that in some distant forest lightning strikes a dead tree, resulting in a forest fire. In the fire a fawn is trapped, horribly burned, and lies in terrible agony for several days before death relieves its suffering. ... So far as we can see, the fawn's intense suffering is pointless. For there does not appear to be any greater good such that the prevention of the fawn's suffering would require either the loss of that good or the occurrence of an evil equally bad or worse."

- Rowe, "The Problem of Evil and Some Varieties of Atheism"

“Traditional free-will approaches – with their move to shift responsibility and/or blame for evil away from God and onto personal creatures – are stalemated by horrendous evil. Human radical vulnerability to horrors cannot have its origin in misused created freedom, because – even if one accepted the story of Adam’s fall as historical (which I do not) – the way it is told, humans were radically vulnerable to horrors from the beginning, even in Eden. The framework within which the primal ancestors made their choices was such that obedient choices meant persistence of the status quo, while disobedient choices would result in the horrendous disarray such as humans have experienced ever since. Even if Adam’s and Eve’s choices are supposed to be somehow self-determined, the fact that the consequences amplify far beyond their capacity to conceive and hence to intend – viz., to horrors of which ex hypothesi they had no prior experience and of which they could therefore have no adequate conception – is not something for which humans are responsible. Rather it is a function of the interaction between human agency and the wider framework within which it is set, and God is responsible for creating human beings in such a framework!”

- Marilyn McCord Adams