Determinism or Free Will
In March of 1975, Peter Van Inwagen published in Philosophical Studies: An International Journal for Philosophy in the Analytic an article that would come to radically reshape our view of our and others' relationships with the world. In this article of his, he explained his “Consequence Argument”, i.e., the idea that Determinism and Free Will are incompatible and conflicting. Below is a slightly modified version of what he termed his “main argument” in favor of the incompatibility between Determinism and Free Will:
P1: If determinism is true, then the conjunction of BP and L entails P.
P2: If J had not done X at T, then P would be false.
P3: If P2 is true, then if J did not do X at T, J could have rendered P false.
P4: If J could have rendered P false, and if the conjunction of BP and L entails P, then J could have rendered the conjunction of BP and L false.
P5: If J could have rendered the conjunction of BP and L false, then J could have rendered L false.
P6: J could not have rendered L false.
Conclusion: If determinism is true, J could not have done X at T.
First, let me perhaps define a few terms present in the argument, and some terms that would be helpful in the future.
L: The physical laws of the world; the laws of nature.
P: The state of the world at T.
BT: Some instant of time earlier than J’s birth.
BP: The state of the world at BT.
Determinism: Given the initial state of the universe, and the laws of that universe, things can only play out a certain way; nothing could have been any different than the way it was, is right now, or will be.
Free Will: The ability to have been able to do something other than what you actually did.
Let me now further clarify this argument by presenting an example of the argument in action.
Et tu, Brute?
If we assume for a moment that determinism has been proven to be true, then we come to the conclusion that the state of the world, as it was before Brutus’s birth, combined with the laws of nature, necessitate that the world be exactly as it was at the moment at which Brutus plunged his knife into Caesar. If, at the exact moment when Brutus was supposed to stab Caesar, he did not, the world would not be exactly as it was at the moment at which Brutus plunged his knife into Caesar (because that is not what Brutus in fact did).
If we assume that the previous statement was true, then we could say that Brutus could have chosen not to stab Caesar at the exact moment when he was supposed to stab Caesar. Brutus could have rendered the statement of the state of the world at that fateful moment false.
If Brutus could in fact do the above-mentioned, and since we had come to the conclusion that the state of the world, as it was before Brutus’s birth, combined with the laws of nature, necessitated that the world be exactly as it was at the moment at which Brutus plunged his knife into Caesar, Brutus could have proved that the state of the world, as it was before Brutus’s birth, combined with the laws of nature, was false.
If he could prove that the two combined were false, then he must be able to prove them individually to be false as well.
However, he would be unable to prove the laws of nature to be false.
Thus, we come to the conclusion that if determinism is true, then Brutus could not have been able to not stab Caesar exactly when he was supposed to. If he was not able to not stab Caesar, then he does not have Free Will.
I think it is now clear how Van Inwagen arrived at his conclusion that Free Will and Determinism are incompatible. One asserts that the trajectory of the world was determined by the creation of the world, while the other asserts that it is possible for someone to do something other than what they did.
In this essay, I will try to argue that Determinism and Free Will are, in fact, compatible.
Objections to Van Inwagen’s claims
An indistinct definition: One of the things that Van Inwagen failed to do clearly in his essay is define the concept of “could have done” explicitly, as a result, there are many ways of interpreting the phrase. I will be presenting three possible ways to disambiguate this phrase:
“If one had wished to do it, one would have done X” -- If we were to apply this way of thinking to premise 6, we would arrive at the following bizarre statement: “If one had not wished to change the laws of nature, they would not have done so”. Now let's take a look at the inversion of the phrase: “If one had wished to change the laws of nature, they would have done so.” This statement is clearly false.
“There was nothing physical that stood in the way of one doing X” -- Again, if we were to apply logic to premise 6, something nonsensical would come to pass. “There was something physical that stood in the way of J rendering L false.” This is extremely ambiguous, and the answer can change under certain circumstances. One objection to this claim is that the laws of nature are what are holding J back from being able to alter the laws of nature, however, this is just assuming and using the conclusion of the argument in the argument itself.
“It made sense for you to consider doing X as an option” -- If we apply this to premise 6 again, we get the following: “It did not make sense for J to consider not doing X as an option.” This runs into the same fallacy as the definition from above, as it presupposes the existence of the conclusion in the argument.
In all three ways presented here that define the phrase “could have done”, the argument falls apart. The best that this argument can prove is the inexistence of both Deterministic and “free” universes.
The Sensibility Argument: Let me first explain a crucial distinction between Determinism and Perfect Predictability. I must emphasize that they are not one and the same. Let me present a definition for Perfect Predictability, while the definition for Determinism has already been presented above. A world with Perfect Predictability (or someone who is able to perfectly predict) is able to know what has happened and will happen, beginning at the creation and ending at the destruction of the universe. If one were given the initial conditions of the universe and the laws of nature and were able to produce an accurate prediction of the state of the world at some particular point in time in the future, we would say that they were able to perfectly predict the future.
In order for my future arguments against the ideas of Van Inwagen to be valid, we must first agree upon something. We are still able to choose in a deterministic universe, although the sense in which the word “choose” is used here may be different from what we commonly think of as the meaning of the word. To be able to “choose”, as the word is being used here, means that although one is still able to make a decision that thing X is what they want to do over thing Y, it has been predetermined that you will choose X over Y. However, people make decisions based on what seems most sensible when they finally decide to choose one thing over another. For example, if at time T I decided to take out a loan in order to start a new business in a deterministic world, and this may be stating the obvious, although it has already been predetermined that I would take out the loan, it would not make sense for me to be taking out the loan in order to do something like sell ice cream in Antarctica. I would be doing something reasonable, which is something I would also choose to do in a world without Determinism. In both cases, if I were to have perfect predictability, I would be able to predict that I would take out the loan over something reasonable, and if every decision we were to make was the best choice we could make based on the limited information one has at any particular moment, then there would in fact be no difference between the deterministic and “free” universes. If the above is the case, then Determinism and Free Will would indeed be compatible, as since both are one and the same, combining the two in a single universe would not be impossible.
One potential counterargument that one may bring up is a situation in which one is incapacitated in some way that disrupts their ability to make “good” decisions. However, this point is irreverent, as the “sensible” choice that I am talking about here is one that is made based on the current circumstances of the individual, regardless of whether they are incapacitated or not. If someone who is drunk decides to do X, then it must seem most sensible to them at that particular instant to do X.
Here is my counterargument in premise-conclusion form:
P1: In a deterministic world, things abide by a “rule of sensibility”. Not only do things abide by the laws of nature, but living organisms also make decisions based on the perceived value of each option that appears to them and chooses the option that appeals to them the most, regardless of their current sobriety.
P2: In a “free” world, things also abide by a “rule of sensibility”. Not only do things abide by the laws of nature, but living organisms also make decisions based on the perceived value of each option that appears to them and chooses the option that appeals to them the most, regardless of their current sobriety.
Conclusion: A deterministic world and a “free” world are one and the same, and thus they are compatible.
Conclusion
In summary, while the arguments for the compatibility between Free Will and determinism are numerous, I have chosen to focus on one particular point, which is my Sensibility Argument. Just to restate my argument, I have chosen to again use the example of the Assassination of Julius Caesar as an example:
In both the deterministic and “free” worlds, organisms act based on how sensible a decision seems to them at a particular moment. The moment at which Brutus’s brain sent a neural signal to his hand, prompting the hand to jab downward quickly into the vulnerable flesh of Caesar, was a result of decisions that Brutus deemed sensible. Regardless of whether the universe in which he exists in this example is deterministic or free, Brutus would do the most sensible thing -- which at the moment is to stab Julius Caesar.
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