(For my MCCC Philosophy of Religion class, as we read essays on the argument from evil against the existence of God.)
PLANTINGA’S FREE-WILL DEFENSE AGAINST MACKIE’S LOGICAL
Mackie accuses the theist of being illogical. Mackie thinks there is no possible way that propositions (1), (2), and (3) can be simultaneously affirmed. (Of “Mackie’s Triad”)
Just as there is no possible way for a person to simultaneously say (a) This object is square; and (b) this object is circular, likewise there is no possible logical way for any person to affirm (1), (2), and (3).
To refute this all Plantinga needs to show is that it is possible to affirm (1), (2), and (3) together. Here it is, in three main points.
POINT 1: It is possible that persons have libertarian free will.
This is the view that causal determinism is false, that—unlike robots or other machines—we can make choices that are genuinely free. Persons have morally significant free will if they are able to perform actions that are morally significant.
POINT 2: It is possible that God has “counterfactual knowledge.”
This has to do with what are called “counterfactuals of creaturely freedom.” (CCFs)
God knows with certainty the actual, contingent truth-value of all counterfactuals of freedom. God has, however, no control whatsoever over the truth-value of these counterfactuals.
This is because persons have free will. On this view God does not control our choices. Here’s an example.
b) If John has free will, then John will not take the bribe.
If (a) is true, then John will take the bribe and God won’t get what he wants. Only if (b) is true will John do what God wants him to do.
So, we have two possible worlds.
One possible world is where (a) is true. Another possible world is where (b) is true. But if (a) is true, then God cannot actualize a possible world in which (b) is true. This is because (a) and (b) are “counterfactuals of creaturely freedom.” Only one of them can be true. Depending on which one is true, it means that the counter-proposition is false.
If God has counterfactual knowledge, then there is a possible world that God cannot actualize.
Therefore God cannot actualize all possible worlds.
Remember, God knows the truth-value of all CCFs. God knows what John will do. But John has free will, so it does not mean that God controls or determines what John will do. Because God knows whether (a) is true or (b) is true, God cannot actualize a possible world where the counterfactual of either (a) or (b) is true.
Given God’s counterfactual knowledge, it is not feasible for God to actualize every possible world.
But Mackie thinks that God can actualize any possible world, including a possible world where persons have free will but always choose what is good.
POINT 3: It is possible that every creaturely essence suffers from “transworld depravity.”
“Transworld depravity” is the condition whereby in all possible worlds that God creates, a being will never avoid at least some evil choices.
That is, it’s possible that, for any creaturely essence you choose, God couldn’t create a world in which that creature is significantly free but always does what is right.
If this is true, then God’s creation of a world with moral good would entail that there is evil. It would logically follow that there is evil.
Therefore, evil is logically compatible with the existence of a perfectly loving, all-powerful God.
So, although there are possible worlds where creatures are free but commit no moral evil, these were not feasible worlds for God to actualize, since the truth-values of the relevant counterfactuals of freedom were not under His control.
Because God gives creaturely agents free will, and transworld depravity exists, God cannot create (actualize) a possible world where things work out just as he wants.
