Can this be calculated? What would it mean to talk about the probability of God?
On the one hand, it seems intuitively ridiculous to assign a mathematical figure to the existence of an entity. On the other, even if we can’t attach a figure, can we not at least discuss its relative probability?
For example, no one knows the probability of me becoming the most famous musician ever. But clearly, it seems smaller than me rolling a six on a die. Can one do this with God?
In the most simple cases, a probability is the quotient of two numbers, the number of distinguished outcomes of an experiment divided by the number of possible outcomes. E.g., when flipping twice a fair coin the probability of two heads is 1/4. Because there are 4 possible results
(head, head), (head,tail), (tail, head), (tail, tail),
and exactly 1 of them is the distinguished result. Concerning the context, one has to ensure that the experiment can be repeated a huge number of times.
When dealing with probabilities in more complex situations like your example, one has to define what the distinguished and what the possible results are. And one has to ensure that the experiment or the situation can be repeated arbitrarily often.
As long as those premises have not been established, it makes no sense to invoke any probabilities. I do not see how to satisfy those premises in your example.
Absolutely. While most thinkers might gravitate towards a theory of probability that mathematizes belief, in the simplest sense, probability is used as a subjective measure of certainty of belief. While not the only theory of probability, subjective is the one our intuition gifts us with long before we understand probability through mathematical theories. From the SEP's article Interpretations of Probability:
Nearly a century before Ramsey, De Morgan wrote: “By degree of probability, we really mean, or ought to mean, degree of belief” (1847, 172). According to the subjective (or personalist or Bayesian) interpretation, probabilities are degrees of confidence, or credences, or partial beliefs of suitable agents. Thus, we really have many interpretations of probability here— as many as there are suitable agents. What makes an agent suitable? What we might call unconstrained subjectivism places no constraints on the agents — anyone goes, and hence anything goes.
Thus, one can be highly doubtful to strongly confident God exists. Of course, a theologian today appeals to more than hunches, and has to deal with philosophers and scientists who ask for more than mere subjective confidence in response to counterarguments that deny God's (or gods) existence.
You would have to give it meaning in order for it to be meaningful.
In everyday parlance, assigning e.g. an 80% chance to something occurring is a way of conveying our internal assurance. It is (often) not based on a calculation actually involving numbers.
To get a numerical answer to some probability question, you would have to model the phenomena in question formally. For this answer to satisfy others, they would need agree that your model is reasonable (even if imperfect). In that case, your number has a clear, formal meaning.
Even for mundane questions such as "am I going to become famous", it is infeasible to mathematically model whether or how likely is it for such a thing to occur. Based on aggregate statistics, we could say something like "only one in so many people of your description tend to become famous", but it would be only be an expectation. It is not as if we could re-run your life from the same starting point such that we could truly say "1.467% percent of the time, you became famous.".
For metaphysical questions, this is all the more the case. How do you plan to model the question of God's existence? Even if you did, how would you get others to agree with such a model? What meaning does a 13% chance of God not existing actually confer to us?
Some people do try to place numbers on such questions, notably the fine-tuning arguments. They tend not to be very convincing broadly, for a variety of reasons. One of them is that they assume insight into the kind of process that generates the universe. For instance, the gravitational constant may be assumed to be drawn randomly from some range of values at the universe's beginning. But it is rather hard to get people to accept such assumptions (and why should they?).
But nothing stops us from relaying our internal assurances. "There's a higher chance God exists than Martians." is a legible sentence - it indicates what you would expect to find and not to find in the world given the chance. This doesn't mean you've formalized the question of God's or Martians' existence, but it does have a clear meaning.
Rolling-of-dice is the context I have the most understanding of probability with respect to, i.e. if I say, "For an n-sided fair die, the chance of rolling whichever side is 1/n," I would be confident that I was using the words "chance of" appropriately. So, and forgive me in advance for this, let us compare the question of existence to having an n-sided die. If the question is just, "Exists or doesn't exist?" then from that vantage, anything has a 50% chance of existing. Or if we modalize things some, we might have a die with three sides possibly but not actually exists, impossibly exists, necessarily exists, and everything has a 1/3rd chance of being one of those.
(Except when something exists necessarily, we would want to say that the probability of its existence is 1. So now per the above, we are asking also about the probability of something being necessary! So, "I know that God exists, but how probable is it that God necessarily exists?" And then, "Ah, but isn't God by definition necessary?" But then, "Ah, but didn't Kant say that neither merely actual nor also necessary existence, are real properties such as can figure in a general, abstract definition?" And now my little knowledge of probability has failed me all but completely.)
Since the object of divine simplicity is not supposed to be the result of a process or even an external dependence/grounding relation, we could also frame the question as, "What is the probability that there exists a being whose existence has no outside cause, and which stands over the rest of the causal order?" Actually, from the standpoint of divine simplicitarianism, we might argue that attributing probabilities to facts about the divine nature would mean introducing substantive distinctions into that nature, which goes against the concept of divine simplicity (and this can be faithfully said more "analytically" or "by definition"). For example, it is sometimes said that in God, there is no distinction between actuality and potentiality; so one might expect no distinction between complete and incomplete probability, there, either.
Simple answer from a mathematician: No, it can't.
Because probability is about so-called “events”, but “God” is not an event. Probability quantifies the possibility for an event to happen. Such a number always depends on the mathematical model chosen. So first comes modelling a situation, then one might quantify.
A mathematical universal “theory of everything” cannot exist mathematically, due to paradoxes which occur from self-references. For instance, there exists no “set of all sets”. The occuring paradoxes are similar to the phenomenon of “the village's barber, who shaves everybody, who doesn't shave himself”.
People, who want to speak about a “probability of God” make the basic mistake, that they didn't define the objects which they want to speak about.
probability is about so-called “events”, but “God” is not an event you are using one (of several possible) mathematical definition, but we are in Philosophy.SE here. You can instead talk about probability of truth of statements (not events), i.e. be a Bayesian, and then everything works fine. Yes, OP does not specify a Bayesian worldview (I assume they are not aware of it, or the question would not have come up really), but in a Philosophy context, one would immediately go to that to answer this question.
assign a mathematical figure to the existence of an entity (here, "entity" clearly means God).
In Bayesian epistemology you assign probability to basically all statements about the world (possibly excluding some basic logical and mathematical facts). In particular, you would have a number corresponding to the "probability of existence of God", which would measure how confident you are that God exists, based on your observations so far. The key idea is that whenever you encounter a piece of evidence for or against the existence of God (e.g. a convincing argument you've not heard before, a scientific observation that's more unexpected if there was no God, an archeological fact that contradicts the contents of the relevant holy book, etc.), you update this number according to Bayes rule, which is a simple mathematical formula which, essentially, allows you to compute how strong a piece of evidence is.
Of course, it's up for discussion whether "probability" is the right word for the numbers mentioned above. Perhaps one would be better of talking about "degree of certainty" or "degree of belief". The word "probability" has the nice feature that one immediately knows what scale is being used (i.e. [0,1]) and how the extreme points (i.e. 0 and 1) are interpreted, so from a purely practical point of view it's a pretty good choice. Beyond that, it's mostly a linguistic / terminological question.
Yes. For instance, the philosopher Richard Swinburne claims the value is greater than 50%.
He is a theist, but he doesn't believe that deductive arguments for God are successful (that is, no one has proved God from premises that even an atheist would agree with). So, he has developed probabilistic arguments for God.
In his book The Existence of God, he argues that monotheism is the simplest explanation for our universe, even without consideration for religious experience or doctrine. The book's Wikipedia article shows his formula and includes some examples of critical responses. He published an updated version of his argument in Is There a God?
the philosopher Richard Swinburne claims the value is greater than 50%. Then I'd love to see a Bayesian giving a probability for Swinburne's statement being correct. :)
Believing in God requires intuition, but proving God's existence requires mathematics. So the question of whether God exists or not requires first choosing whether you believe the results of intuition or the results of mathematics.
For a long time in the past, and even now many people talk about God in an intuitive way, so it's relatively easy, because everyone can confirm their intuition.
But to use mathematics, you must first understand the universe in its entirety. Because the concept of God includes the creator of the universe, and at present we cannot fully understand the whole universe by mathematical methods, how can we understand the creator of the universe by mathematical methods?
Of course not. At least not for the almighty god, that many people assume.
Were there to be a probability of there being the almighty God then God would be limited by probability, and would thus not be an almighty god. (The probability would be 0.) Now the fact that the almighty God is the first cause of all things causes some logical problems. For one how can anyone speak about God existing or not existing based on what we see in the universe when there is no hypothetical instance in which God does not exist? Furthermore, it begs the question of why God is the way He is, and does what He does? But this doesn't seem to possibly have an answer since if there was a cause for Him to be the way He is, then He would be beholden to that cause, again meaning he isn't the highest power, and ultimately not an almighty god.
On the other hand, many other answers have brought up an interesting point. What is a god? Would the Bible really be incorrect to say that God is Almighty even if He cannot create what he cannot lift, cannot make 2+1 = 4, or cannot do what is by definition impossible? If God may be so limited, then why can't He have His own causes?
If you can call a "god" "God" while they are still subservient to probability then the answer is yes! There can be a probability of God. However, in this case, isn't Probability, or rather since probability relies on mathematics, Mathematics the true God? But if that is the case then that means Mathematics decided to make God, or rather based on some degree of randomness decided to either make God, or make the universe on its own! Wouldn't such decision-making power be outside the realm of Mathematics, however? Wouldn't it make more sense to call the decider God? In which case Mathematics should at the very most be considered a part of God. Thus we again have God at the very top with no answers as to why He is the way He is, and no room for reality without Him.
tl;dr: The second half of Kristian Berry's answer is right. The first part about assuming equal weight to all different possible answers seems a bit silly to me.
This answer is within the context of a Bayesian worldview, which, as has been explained in other answers, basically associates a probability with any and all statements you can come up with.
What would it mean to talk about the probability of God?
A very simple way to think like a Bayesian is to ask yourself: how much would you bet on the proposition being true, to expect a positive outcome? In this particular case, there is the famous Pascal's Wager, which says that it is safer to bet on the existence of God because you have to invest relatively little (a little bit of time and maybe some money for donations for your church...), but can gain an enormous amount (eternity in heaven). Or if you don't believe in god, you are betting the little time and money you safe in life vs. an eternity in hell.
Can this be calculated?
No. By design, everything and anything that is believed about God is such that it is not visible, falsifiable, or in any other way open to objective criteria. Almost by definition, anything that is up for objective research, logic, or anything of the kind (i.e. anything that could go into a calculation) is not part of the volume of believes about God.
As with most statements, it is impossible to assign a probability of 0 or 1, because this would mean we knew things that we cannot (by design) know or not know. This is not a special property of this proposition, but goes for almost anything a Bayesian is thinking about.
On the one hand, it seems intuitively ridiculous to assign a mathematical figure to the existence of an entity. On the other, even if we can’t attach a figure, can we not at least discuss its relative probability?
Sure, every Bayesian is free to come up with a subjective probability they subscribe to, for any given statement. It is not so much about the "objective" probability. It is "normal" that different Bayesians assign different probabilities to the same question, simply because it usually depends on what knowledge the person has available at any point in time. For example, for me it is relatively simple to assign a probability to "will it rain in 30 minutes in the city I am in right now" by looking out of the window and witnessing perfectly blue sky, 30°C and zero clouds, in an area that is not usually experiencing sudden weather changes. But I could not say anything with confidence about the weather in some city on the other side of the globe, unknown to me, because I simply do not know the local weather patterns. If I have access to a smartphone weather app, my surety would increase. And so on and forth.
Heck, for the question of whether God exists, there even is a formal (albeit possibly slightly tongue-in-cheek?) scale, in the form of the Spectrum of Theistic Probability.
For example, no one knows the probability of me becoming the most famous musician ever.
Oh, but we do, at least on a broad spectrum. If we know nothing whatsoever about you, then we can simply divide "you" (i.e., 1) by the number of humans, and get in the rough ballpark of a probability of 1/8.000.000.000. Knowing that you have a computer or smartphone probably catapults you into the 1/1.000.000.000 area (just to pull numbers out of thin air). Instead, if we knew that you are at least in the top 100 musicians right now by some metric, say your place on Spotify playlists, we could relatively conservatively just assume 1/100 as a chance. The more we knew about you, the better the result would be (especially if we knew anything about your musical career so far). We would never, in any case, assign a probability of 0 or 1.
But clearly, it seems smaller than me rolling a six on a die.
Clearly, yes.
Can one do this with God?
Sure!
For example, I consider myself at roughly 6.99 on the Spectrum mentioned above (and the only reason it's not 7 is because 0 or 1 are not valid probabilities in my particular worldview, for almost any question). In quite a few decades of life, I have not witnessed anything whatsoever that speaks to me as counting towards the truth of that statement. Conversely, for all "proofs" or "signs" that religious people have come up, I can easily think of purely logical, objective, psychological etc. explanations. I can easily think of ways how a religion can manifest some thousand years ago and grow to what it is today, with no mystical influences whatsoever. I have access to logical arguments along the line of "there are at least X major religions, everyone of them using the same arguments to tell me that they are the only true one, so..."
If, tomorrow, I get abducted by a literal arch angel, be transported into Heaven, talk with God and the Devil, get super powers of wisdom and capabilities and brought back as the next Saviour, then my personal believes could easily change (I assume). I mean, I would still need to figure out for myself whether it's just aliens, whether I live in a simulation instead, and so on and forth, but my position on the Spectrum would probably shift just a teeny tiny little bit, at least.
The answer is 'No'.
You can never assign a probability to something that has never been observed.
Your examples of throwing a dice ending up with six against you being world famous are irrelevant to your question:
We know that people throw sixes all the time. Thus, there is a probability of throwing a six.
Some people are famous, thus there is a probability for you to be famous too.
God have never been observed, and thus there is no baseline from where we can estimate a probability.
By the way, I have heard endless arguments for the existence of God, and common for them all is that they also apply perfectly to unicorns, gnomes, fairies and Santa Clause.
...and every other deity ever invented by man.
TL;DR Yes
In Bayesian probability, a probability represents the plausibility of an event or proposition. So as we can obviously speak of the plausibility of the existence of God (this SE demonstrates that), the corresponding Bayesian probability clearly exists.
If by god, you mean the omniscient creator of the universe, the answer might be best asked in the manner of whether we can observe the probability of anything, and if anything and nothing are the same. If there is nothing, and we are nothing, then nothing is a non-creation and there is no basis for being. If, however we are something, then we wonder where we came from, and start to ask questions about what, how and why. For some of us, there is a feeling of sensitivity of where we came from (children have an innate sense, that we adults have for the most part lost). That takes us back to the nothing or anything, as in 'anything' is possible, and 'nothing' is impossible. If you read that a different way, and say it, you will realize that ( anything is possible, i.e., god exists is possible), and 'Nothing' (god does not exist is impossible.).
God will speak to you my son. He will lift you up. He will help you to stand. All you need to do is look and listen. He will come to you.
