The ability to do otherwise is often referred to as the principle of alternative possibilities (PAP). Although it is often argued that the ability to do otherwise is not necessary for libertarian free will (LFW) to obtain, most affirm that the PAP is sufficient for LFW. That is to say, if the PAP is true, then LFW is true.
With that said, I am noticing more and more libertarians exclaiming that the PAP is not necessary for LFW. While this might be true of humanity in the physical/material substrate, it seems that this is almost a surrender of the view — and some seem like they are almost enthusiastically willing to give it up entirely. I, for one, think this is a big mistake for several reasons. First, I believe the ability for humans to do otherwise — at least in the immaterial substrate — is clearly taught (or heavily implied) in the Bible (See Molinism is Biblical). Second, I believe that if the PAP is false then life is absurd! I concede that, on a material level, there could be circumstances where P cannot ‘do’ otherwise (referring to a physical action); however, I believe for there to be free will and moral accountability, the ability to ‘think’ or ‘will’ otherwise, is necessary. (I refer to this as the principle of alternative possible thinking or “PAP-T”).
Luis de Molina is one of the greatest advocates of LFW in the history of the Church. Will is a free cause according to Molina. It enjoys a freedom from necessity which is defined in the following way:
“That agent is free, which, when all requisites for acting are present, can act and not act, or act in such a way that it can equally act in a contrary way. And it is because of such a freedom that the faculty through which such an agent can act this way is said to be free. . . . And free will (liberum arbitrium) . . . is nothing else but the will, which is formally free according to our definition, when it is preceded by a judgment of reason” (Concordia, disp. 2, n. 3, ed. Antwerpen, 8a).
Not only did Molina affirm the PAP, some determinists believe that if libertarianism is true, then the PAP would also be true. In fact, Guillame Bignon (although he is definitely not a libertarian) argues that all libertarians should affirm the PAP in his recent book. Bignon writes:
“No matter how modestly one defines libertarianism, and its underlying indeterminism, then, they necessarily entail the existence of alternate possibilities . . . the possession of libertarian free will entails the categorical ability to do otherwise than one does.” (Bignon:Excusing Sinners & Blaming God:2018:126)
Although I do not agree with Bignon on many accounts, I think he might be on to something in this regard.
As briefly alluded to earlier, a vital distinction needs to be made between the ability to physically act otherwise and the ability to mentally think otherwise. I contend that the former might not need the PAP, but the latter does (I refer to this as the principle of alternative possible thinking or “PAP-T”). Does the PAP, by definition, only include material abilities? I think many incorrectly assume it is only regarding physical actions, but that assumption is what I am attempting to challenge.
It is often asserted that thought experiments known as “Frankfurt examples” show that the PAP/”ability to do otherwise” is not necessary for freedom or responsibility (See Semi-Compatibilism & Responsibility). With these thought experiments in mind, Kirk MacGregor makes a great point:
“Libertarianism needs the PAP, where “do otherwise” is understood broadly enough to include “think otherwise.” Any Frankfurt cases still allow for the chooser to think otherwise and therefore do not serve as legitimate counterexamples to the PAP. It is only by construing “do otherwise” narrowly to action that the Frankfurt cases appear to undermine the PAP.”
Some of my fellow libertarians think that PAP-T is not necessary for rationality. I disagree and have made it clear why “free thinking” is vital to the concept of rationality (See A Revised Freethinking Argument). With that in mind, consider the following statements:
1- Rational affirmation is impossible on exhaustive determinism because something external to the agent causally determines the agent in such a manner that it is impossible for the agent to think otherwise.
Compare the previous view with the next:
2- On the non-PAP view of libertarianism, even though nothing external to the agent is causally determining the agent, the agent is still in the same boat as the determinist in that it is impossible for the agent to think otherwise.
This raises additional questions as to exactly why — if the agent is free in a libertarian sense and not determined via any external source — the agent simply has no ability and cannot think otherwise. I have heard of nothing but ad hoc responses to the question or just an appeal to mystery, but those do not advance the conversation.
I digress . . . Evan Fales supports my case that the PAP is vital for rational deliberation:
“The analysis of free choice which I shall propose derives, in part, from Aristotle’s conception of practical reasoning. According to it, acting freely consists in acting as a result of rational deliberation over what act to perform. To choose is to deliberate: it is not to perform some superadded ‘act of will’. This conception of freedom makes obvious the connection between being free and having the capacity to engage in rational deliberation. It also makes it clear why PA [PAP] is so central to the possession of a free will: to have a free will is to have the capacity to act as a result of engaging in efficacious deliberation; but in order for my deliberation to have any point, I must at least believe that I have before me two or more genuinely possible alternative courses of action. Of course, I can take my deliberation seriously even if this belief is false; but in that case, my supposition that I am free to choose is a delusion. So freedom consists in efficacious deliberation – i.e., in the performance of deliberation-guided actions; and efficacious deliberation presupposes genuine alternatives, each possible given antecedent conditions.” (Fales: International Journal for Philosophy of Religion 35, No. 2: 1994: 83)
John Searle pointed out that for rationality to obtain:
“Actions are rationally assessable if and only if the actions are free. The reason for the connection is this: rationality must be able to make a difference. Rationality is possible only where there is a genuine choice between various rational and irrational courses of action . . . If the act [cannot be otherwise] then rationality can make no difference. It doesn’t even come into play…” (Rationality in Action:2001:202)
In the original quote Searle refers to an act being “completely determined” as opposed to “cannot be otherwise,” but I do not see any relevant difference regarding the consequences that follow. Searle clearly affirms the PAP is essential for rationality earlier in the same book:
“Rationality is only possible where irrationality is possible. But the possibility of each requires freedom. So in order to behave rationally I can do so only if I am free to make any of a number of possible choices and have open the possibility of behaving irrationally . . . When we perform conscious voluntary actions, we typically have a sense of alternative possibilities.” (66-67)
Angus Menuge seems to agree and notes that Searle affirms a libertarian freedom that includes a genuine ability to choose otherwise:
“Rationality presupposes an entity with libertarian free will that can act on some reasons rather than others.” (Menuge:Philosophia Christi, Vol 15, No 1, 2013:95)
Searle appears correct, and if so, then even if one asserts that LFW exists but the ability to think otherwise (PAP-T) does not, then nothing ever really “makes a difference” because no one can really think other than the way they do think — even if they are not causally determined via an external source.
Regarding this view, William Lane Craig and JP Moreland write:
“If one is to have justified beliefs. . . then one must be free to obey or disobey epistemic rules. Otherwise, one could not be held responsible for his intellectual behavior.” (Moreland & Craig:Philosophical Foundations:66)
The phrase “to obey or disobey” implies the PAP when it comes to thinking, rationality, and “intellectual behavior.” That is the way I see it too, but perhaps I have no ability to think otherwise!
Stay reasonable (Isaiah 1:18),
*A note of thanks to Johnny Sakr for the Molina references and suggested edits!
 Molina, Concordia, disp. 24, n. 8.
 This quote (used by permission) is from my personal email exchange with Kirk MacGregor.