William Rowe's book asks the question: Can God be Free? First, he gives an interesting historical introduction to the subject covering the views of Gottfried Leibniz, Samuel Clarke, Thomas Aquinas, and Jonathan Edwards; meanwhile he chimes in with his critique of their views from time to time. Then he discusses more recent treatments, such as Adams, Kretzmann, Howard-Snyder, Morris, Hasker, Wainwright, Langtry, Menssen, Wierenga, Flint, Swinburne, and Talbott. Rowe seems to hold that libertarian freedom is necessary for responsibility and he dismisses compatiblism as 'language gone on holiday'. Based on Leibniz's argument that God must have created the best of all possible worlds, Rowe argues a forking maneuver: either creation was necessary and God is not praiseworthy or God doesn't exist.
Leibniz articulated two ideas that vital to the discussion. The first is the Principle of Sufficient Reason (PSR), which states: there ought to be a reason why things should be so, and not otherwise (9). Both Clarke and Leibniz affirmed this principle in their debate, but Clarke meant something other than Leibniz did and Leibniz questioned if Clarke clearly understood it. Clarke indicated that sometimes "the mere will of God" is the only sufficient reason; providing the example of God's choice to create the universe here and not some other part of absolute space (Clarke was a Neutonian in physics) (11). Leibniz saw this move as bootstrapped. Leibniz's second idea was the Principle of Best: God never prefers the less perfect to the more perfect (20). Leibniz notes God is bound by moral necessity, to make things in such a manner that there can be nothing better: otherwise... he would not be satisfied with his work, he would blame himself for its imperfection; and that conflicts with the supreme felicity of the divine nature (17). This immediately threatens God's libertarian free will. Rowe gives the example of God thinking about creating a good world or a bad world. To say that God freely created the good world seems to imply that he was free not to do so, that he could have created the inferior world, or refrained from creating either world. But if his perfect goodness requires him to create the good world, how is it possible that he was free to create the inferior world or not to create any world? (13) Leibniz suggests a compatiblist solution; the distinction between moral and natural necessity corresponding to the distinction between certainty and necessity. Thus it was certain that God create the good world, but not necessary that He do so. Rowe rejects Leibniz's solution as inconsistent, given Leibniz's principles.
Next Rowe reviews Leibniz's libertarian opponent, Samuel Clarke. Clarke held God is unable to sin but he also holds God is all powerful. He reconciles the two by saying "it is no diminution of power not to be able to do things which are no object of power. And it is in like manner no diminution either of power or liberty to have such a perfect and unalterable rectitude of will as never possibly to choose to do anything inconsistent with that rectitude. (30) Rowe points out that while this doesn't diminish God's power, it does diminish God's freedom; God is not free to sin. Then he extends this idea to God's goodness and creating the best possible world and concludes God is not free to create other worlds.
Then Rowe reviews Thomas Aquinas. Rowe claims Aquinas held God necessarily wills His own goodness and God necessarily had to create some world to share or diffuse His own goodness. While it's true Aquinas taught God necessarily wills His own goodness, Aquinas explicitly denied creation was necessary. Aquinas states: "God, therefore, can will the non-existence of anything whatever apart from Himself. Hence, it is not of necessity that things other than Himself exist." (Summa Contra Gentiles Book 1 Chapter 81 - THAT GOD DOES NOT WILL OTHER THINGS IN A NECESSARY WAY) Rowe seems mislead on this point by Aquinas' statement: "Moreover, the communication of being and goodness arises from goodness. This is evident from the very nature and definition of the good. By nature, the good of each thing is its act and perfection. Now, each thing acts in so far as it is in act, and in acting it diffuses being and goodness to other things. Hence, it is a sign of a being’s perfection that it “can produce its like,” as may be seen from the Philosopher in Meteorologica IV . Now, the nature of the good comes from its being something appetible. This is the end, which also moves the agent to act. That is why it is said that the good is diffusive of itself and of being. But this diffusion befits God because, as we have shown above, being through Himself the necessary being, God is the cause of being for other things. God is, therefore, truly good." (Summa Contra Gentiles Book 1 Chapter 37 ) Commenting on this text, Rowe states: "The difficulty with viewing God's creation of some world or other as a free act is that God's goodness is a necessary aspect of his nature, and if goodness is necessarily 'diffusive of itself' then it would seem to be necessary that God express his goodness in crating some world or another." (37) But Aquinas isn't saying goodness is necessarily diffusive of itself. He's saying God can and did diffuse goodness. In other words, when God created the world and said "it is good", this is evidence that God is good.
Aquinas also said there is no 'best world'; rather there are an infinite number of possible worlds. From this, Rowe concludes that Aquinas taught there is an infinitely increasing number of better and better possible worlds without reaching a 'best'. I am not sure if this is necessary conclusion or not; there could be an infinite number of equivalently good worlds. But in any case this view becomes Rowe's main opposition throughout the rest of his book.
Rowe concludes his review of the history of the issue with Jonathan Edwards. Edwards taught that God's creation of this world was necessary, given God's nature, but still maintained God created it freely (link). Edwards used compatibilism to reconcile the apparent discrepancy. He distinguished between the power to do something and the power to will to do something; which led him to distinguish between natural and moral inability. Edwards asserted we had the power to do otherwise if we willed to, but not the power to will to. (59) Rowe combats this notion based on moral intuitions and case law involving the ability to choose otherwise.
Rowe then moves into more recent discussion of the issue of God's freedom. Robert Adams argued that it wouldn't be immoral for God to create a less than optimal world because no one is harmed in the process. Those not created are unharmed, because they don't exist. Those created are better off existing than not existing. (80) Rowe counters that perhaps God is not morally obligated to create the best world, but doing so is a supererogatory act - a good act beyond the call of duty. (82) Adams argues that God's love is unconditional; not based on the merits of the one loved, so God's choice can't be based on the best possible creation. (83) Rowe objects that then love is not the reason God creates this or that world.
Rowe posits: If an omniscient being creates a world where there is a better world that it could have created, then it is possible that there exists a being morally better than it. (91) So in the scenario with an infinite number of increasingly better worlds with none being best, if God creates world 100 and could have created 101, it is possible there exists a being morally better than God. Howerd-Snyder counters that any being led by such a principle is irrational and hence not omniscient, nor would he ever create, given for each world there is one better. (94) Rowe counters that within a segment of infinity, say worlds 100 to 200, if God creates world 150 then it's possible that a being morally better than God would have create a world higher than 150. Wierenga counters that God rejected an infinite number of worse worlds and an infinite number of better worlds. That's true if God creates 150, 175 or 200. It's impossible for God to create a world with none better and therefore God is not obligated to do so. (135) In a revealing response, Rowe objects that the incremental difference between 175 and 174 is the same, but once you get to one, the increment decreases. Thus you go from 1 to 1/2 to 1/4 and so forth. Ultimately, there is no appreciable, felt difference to any sentient being. (136) Further, this view amounts to saying "God is free only when it does not matter what he does". (140)
Rowe concludes his review of the contemporary debate by rejecting Talbott's compatiblistic solution as 'language gone on holiday'. (149) Rowe concludes the book by giving his theistic opponents two options; it doesn't matter which world God creates or God necessarily created the world he did.
Scripture plainly asserts God has both ultimate responsibility (Genesis 1:1) and alternative possibilities (Matthew 3:9, Matthew 26:53, Ephesians 3:20). When something leaves the hand of the Creator, it is and must be good ( Genesis 1:31) but we, via our own freedom, can make ourselves worse off (2 Peter 2:21, Matthew 26:24). God's asseity means He does not need us for His blessedness (Romans 9:5) but our blessedness is contingent (Matthew 5:1-10). So from the perspective of God's blessedness , goodness, holiness and justice all worlds are equivalent, but from the perspective of our blessedness, there is an infinity of increasingly better worlds with none best. We could be better off, but God could not.
I think the idea that God chose to create the best possible world is self-contradictory. If God can't create a world, it's not a possible world. It's not causally possible, because God can't create it. It's not logically possible because God's creating the world implies the contradiction of a unwise, all wise God. Something would have to be as good as God for God to have to create it, which is impossible. Ultimately, the idea that God had to create this world ascribes to creation what belongs to the Creator and undermines God's sovereignty, in that God's not in control, His holiness in that He had to create evil and His omnipotence in that He can't do anything other than what has and will happen. So for me, Leibniz's idea is off the table.
When pressed by Adams and Wierenga, who basically question Rowe's standard for defining 'best' or his scales for judging God's morality, Rowe retreats from his argument that 'possibly there exists a being morally better than God' to 'it doesn't matter which world God creates'. This contradicts his holding to libertarian freedom and accepting agent causation. How is agent causation satisfies the Principle of Sufficient Reason for man, but not for God? What's happening here is Rowe is looking at the first link in a chain and asking what comes before it. He seeks an integer lower than one. God's will is the first cause; so looking for the cause of God's will seems pointless.