In the previous post, I discussed Anselm's ontological argument for the existence of God and promised to discuss the modal ontological argument for the existence of the same, and I will soon. But before I begin the essay proper, I want to register a small concern, a small anxiety. Who reads this blog? What makes it worth reading? Sometimes I discuss my life, a very important topic to me, obviously, and I think very important generally because I am discussing a Mental Health Service that has failed not just me but seems to fail everyone. I am a paradigmatic case. I am also trying to prove that people diagnosed schizophrenic (in my case, wrongly) can be intelligent, articulate, and rational, human, in a culture which continually 'others' people who have had the bad luck to be diagnosed with serious mental illnesses. I also write about philosophy and narratives, about nature vs. nurture, about fiction and reality, I hope in a way that is accessible even to laypeople with little academic experience. I tend to assume that my readers are at least a little familiar with thinkers like Sam Harris, Bret Weinstein, Jordan Peterson, and Bill Maher, a not unreasonable assumption given the global profile these public intellectuals and commentators have. I feel that the insights I bring to the table are worth sharing but I do not know if they are reaching people who are versed in these disciplines themselves and know an innovative idea when they chance across it. I would really like it if CosmicSkeptic himself, Alex O'Conner, were to read this post and the previous one but I am forced to concede that this is most unlikely. I suspect, and secretly hope, that the figures I receive concerning the number of hits this blog collects are underestimates, but I cannot know this for sure. If people in the world enjoy this blog, give me a sign, and I will continue to write about the things that interest me.
And now, without further ado, onto the modal ontological argument, one of several arguments for the existence of God. This post may be quite long but I hope it will be interesting.
The very simplest form of the modal ontological argument, as it is deployed by religious people, runs as follows:
P2. God possibly exists.
C1. Therefore, God necessarily exists.
C2. Therefore, God actually exists.
This argument can be rephrased in the following way, if we accept the 'possible worlds' formulation of modal logic:
The problem with this argument is that we can deploy the exact same structure and reach the exact opposite conclusion. The atheist can counter it in the following way:
Interestingly, many atheists are prepared to accept the first premise in the argument, the premise that God's existence or non-existence is necessary (although there are some people, such as Tom Senor, who have argued that God could be a 'brute contingent fact', that God could be the causeless creator and lord of some possible worlds and not others). The difference between the two opposed positions is in the second premise. The Christian says, "Of course, God could be possible!" while the atheist says "Of course, we could have a world without God!" To both parties, it just seems obvious. I would like to suggest that perhaps there could be a problem with modal logic itself that leads to this seemingly insurmountable impasse.
The modern study of modal logic began in 1912 with the publication of a number of articles by C.I. Lewis and major developments occurred in the mid-twentieth century as the result of work by David Lewis and Saul Kripke; although they had two somewhat different perspectives on it, both Lewis and Kripke subscribed to and developed the idea of 'possible worlds'. The argument for possible worlds is simple. To quote Wikipedia:
(2) So there are other ways how things could have been.
(3) Possible worlds are ways how things could have been.
(4) So there are other possible worlds."
David Lewis coined the term 'modal realism' to describe his own metaphysical system that seeks to accomodate the idea of 'possible worlds'. In Lewis's view, all possible worlds are just as real as the actual world, although they are spatiotemporally isolated from each other and cannot interact. To say something is possibly the case is to say it is definitely the case in at least one possible world. The only difference between the actual world and all the other possible worlds is indexical – meaning that the actual world is 'our' world in the same sense that I can say I'm here in my apartment in Eden Terrace. (Importantly Kripke, by contrast, argued that modal logic is simply a useful way of approaching the idea of possibility, that it does not commit us to the claim that other possible worlds exist.)
Modal realism is enticing because it seems such a promising way to deal with some difficult ideas in logic and philosophy generally – but it runs into serious trouble if we consider what it means for something to be identical to itself. Consider the proposition, "It is possible (as of 6 October 2021) that Donald Trump is still President of the United States". The ordinary person on the street would say that this is false but I believe that both Lewis and Kripke are obliged to say that it is true, that there is a possible universe in which Trump is still President. The obstacle modal logicians must try to hurdle is Leibniz's law, a corollary of which is that if two things have mutually exclusive properties then they cannot be the same thing. In the possible world, call it w, in which Trump is still President, he has the property 'President of the United States' while in our own world, the actual world, he has the property 'no longer President of the United States'. This suggests that the Trump in w is a different entity to the Trump in the actual world, our world. Our Trump is not the same being as the Trump in w. Lewis embraces this conclusion by advancing his 'counterpart theory': in this theory, the Trump in w is a counterpart to the Trump in the actual world but not the same person. We might say, "There is a possible world in which some person known by the name Donald Trump in that world is President of the US." However, if we accept counterpart theory, we are compelled to parse the sentence "Trump might have won the 2020 Presidential Election" as saying "In our actual world, Trump lost the 2020 election but there is a possible world, w, in which a counterpart of Trump won the election." This runs counter to our common sense understanding of the unanalysed sentence that it concerns one individual, not two. Lewis and Kripke defend modal logic by saying it aligns with the ordinary way ordinary people use language but I contend that it doesn't, and I shall argue for a different way of understanding modal logic that I contend does a better job conforming with the way ordinary people use the words "necessary" and "possible".
Let us consider the word "necessary". Immanuel Kant argued that all necessary truths are knowable a priori but for some time now, as I understand it, this contention has been chipped away at. Kripke himself has shown that identity statements, such as water being H2O, can be necessary truths known a posteriori. I want to go much further. I want to argue, now, that there is only one world, the actual world, and that everything that occurs in it occurs necessarily. The past is unalterable and the present proceeds from the past deterministically as does the future. A statement like "Donald Trump might have won the 2020 election" implies (as Lewis and Kripke both claim) that the world could be some other way but, if one was gifted with God-like omniscience, it would be evident to one that there is no other way the world could be – unless we suppose some kind of flexibility at the very beginning of time (as I discussed in the post "The Weak Anthropic Principle"). In thinking this I am not alone. Sam Harris has several times suggested in his podcast that there might be no possibility, only necessity. The idea that everything is necessary is founded on the idea that everything is deterministic; modal logic, as Lewis and Kripke present it, seems to suggest that the universe is not deterministic. But where does this idea, the idea that the universe is probabilistic, come from? It seems that the idea that there are other ways the universe could be is buttressed by two arguments, the argument from free will and the argument from quantum uncertainty; if people have free will, it seems there are other ways the world could be as the result of the free choices that people make, and if quantum uncertainty is understood as it often is, the world is constantly spawning alternate universes. I shall not present an argument for the non-existence of free will here but rather direct the reader to Harris's book Free Will and to the rather brilliant Youtube clip Compatibilism Debunked by CosmicSkeptic. Nor will I attempt to refute the idea of quantum uncertainty here but instead refer the reader to my own posts "Probability and Schrodinger's Cat" and "Probability and Schrodinger's Cat Part 2". In these posts, I argued that it is conceivable that the universe could be deterministic if we posit a non-local hidden variable theory. I suspect that it might be a bridge too far to seek a proof that the universe is deterministic; in an analogous way to faith in God, it requires a leap of faith to believe everything that happens happens necessarily. Nevertheless this is the contention I wish to run with now.
If everything that happens happens necessarily, why do we have words like "possible" or verb forms like "might have"? I believe that we use terms like these in situations where we lack all the relevant information. If a friend tells me to take an umbrella because "it is possible it might rain", my friend is saying, in effect, it will definitely rain or not rain but that she does not know which. She does not have perfect knowledge of all the meteorological data that would be required to make a fully accurate prediction. The reason the sentence "It is possible that Napoleon won the Battle of Waterloo" strikes the ordinary person on the street as false is that the person, assuming he or she has the rudiments of an education, most likely accepts the fact that Napoleon lost as a given. Now consider the statement, "It is possible that Covid-19 originated in a virology lab in Wuhan." Lewis and Kripke would propose that this sentence should be parsed as saying, "There is at least one possible world in which Covid-19 leaked from a virology lab in Wuhan". But this misrepresents what people who utter this sentence mean by it. People mean that, in this world, the actual world, Covid 19 either definitely leaked or didn't leak but that they can't be sure if it did or not. The proposition "p is possible" really means "I don't know for sure if p is true or not". There are many things in the world about which we cannot be confident and this is where modal logic (in its revised form) comes in useful. There may even be limits on what we can know – this was the conclusion I reached in the posts about Schrodinger's cat. It may be that the Schrodinger equation and Dirac equation, the Heisenberg Uncertainty Principle, prescribe the furthest boundaries of what human consciousnesses can ascertain about physical reality. Probabilist statements, in the final analysis, indicate ignorance rather than provide insight into alternate realities. (It is possible that the type of modal logic I am proposing here has the name 'epistemic modal logic' but, as of writing this, I cannot be certain.)
I have talked about modal logic before in the posts "Modal Logic", "Modal Logic Part 2" and "Modal Logic Part 3". I wish, now, to confess an error that I made in these posts. I thought that the statement "It is possibly the case that p" is equivalent to the statement "It is possibly the case the not-p" and this was the foundation of the arguments I made in those three posts. I was wrong – at least if we accept the modal logic system proposed by Lewis and Kripke. The expression "It is possibly the case that p" means, if we accept the forms of modal logic they advance, "There is at least one possible world in which p is true". That is, the proposition "It is possibly the case that p" is true even if p is true in all possible worlds. To say something, p, is possible is to say that the negation of it is also possible – or that the negation is impossible, that p is necessarily true, that p is true in all possible worlds. I didn't consider the 'or' when I wrote those posts. I now know a little more about modal logic (although I am far from being an expert). However, if we accept the metaphysical picture I have advanced in the preceding paragraphs, the Judd-Harris picture (to coin a term), we do have to reject the possible world semantics put forward by Lewis and Kripke and others before them. New logical axioms are required. The proposition "It is possible that p" does entail "It is possible that not-p" and the proposition "It is necessary that p" no longer implies "It is possible that p". The system I am proposing is pretty much the same as the system I proposed in "Modal Logic Part 3" – even though, when I wrote that post, I had a faulty understanding the work done by Lewis and Kripe.
I want now to raise another curious problem in modal logic which has some bearing on what I have been discussing. Consider the proposition: "It is possible that Napoleon won the battle of Waterloo." As I said above, most educated people would regard this proposition as false. Yet if I say, "It is possible that Napoleon might have won the battle of Waterloo," most people would regard this as true even though the two propositions seem to be equivalent. The reason for the difference is that people generally accept a probabilistic view of reality, the idea that there are different ways the world can be. Lewis and Kripke defend their modal logic systems by saying that it aligns with the ordinary way ordinary people use language. And I am departing from this principle of ordinary language use when I say that everything is deterministic, necessary. However, if we are to make advances in knowledge, we must sometimes recognise that the assumptions we inherit may be wrong, as Einstein and de Broglie, to pick two random examples, did, and as Alfred Wegener did when he proposed the idea of continental drift. And the popularity of Sam Harris shows that people are willing to countenance the idea that there is "no possibility, only necessity."
And now finally we can return to the version of the ontological argument that I presented at the beginning of the essay. The first premise, "God either necessarily exists or necessarily doesn't exist" is, according to the Judd-Harris modal logic system, trivially true because all things either necessarily exist or don't exist. The second premise, "It is possible that God exists" can be translated as "I do not know if God exists or not." And nothing follows from these two premises – certainly not the claim that God exists or even the claim that He doesn't.
The reader may think that the simple ontological argument I have presented is a straw man, and may wonder if there are stronger versions of the ontological argument for the existence of God. There is at least one. Randomly browsing the Internet recently, I came across a Masters thesis in Philosophy by one Andrew Kirschner, a student who had previous degrees in Biblical Studies and Christian Apologetics. In the thesis Kirshner presents his own ontological argument for the existence of God in simple form and then devotes the rest of the thesis to detailing and explicating the steps in his main argument. The thesis is sometimes a little clumsily written but I nevertheless recommend it to readers. His argument, in a nutshell, runs as follows (and this is a quote):
exist, or necessarily do not exist.
P2 If an entity can be conceived, then that entity either actually exists, or merely possibly exists.
P3 God can be conceived.
C1 Therefore, God either actually exists, or merely possibly exists.
P4 Something is necessary if and only if that entity is totally non-contingent, or if it is
inconceivable.
P5 If something is necessary, then that entity either necessarily actually exists (if it is totally non-
contingent), or is impossible and thus necessarily cannot exist (if it is inconceivable).
P6 God is totally non-contingent.
C2 Therefore, God is necessary.
C3 Therefore, God cannot merely possibly exist.
C5 Therefore, God actually exists."
