Thomas Bayes was an English Presbyterian minister and mathematician who wrote “An Essay towards solving a Problem in the Doctrine of Chances”. It was read to the Royal Society in 1763. It provides a means of calculating the probability of a statement being true or false by using available evidence. If we have no evidence at all, the answer of probability of something being true or false is 50%. Just like flipping a coin there is an equal chance the coin would come up heads or tails. Now we factor in the evidence using the Bayes’ formula:
P(A/B)=P(B/A)P(A)/P(B)
P(A) is that the probability of A is true and P(B) is the probability that B is true and (P)(B) ≠ 0. Each point of evidence is assigned a number between 0 and 1, based on its probability of being correct. Nothing is absolutely certain (i.e. has a value of 1), and conversely nothing is absolutely impossible (i.e. has a value of 0). For example, the odds that you exist is 0.999. Rene Descartes upped it to those high numbers with his “Cogito ergo sum” argument. But there is still that 0.001 chance that you are just a brain floating in an electrolyte bath in someone’s lab being stimulated with electric probes to induce the various experiences you interpret as reality. This is further complicated by the suggestion of Socrates, that all the observations that we hold as immutable truths may just be shadows on the wall of our cave, the real events taking place outside our cave, the walls of which are upheld by our senses. Everything is measured in probabilities. Bayes has given us a tool to quantify these probabilities. It is known as Bayes’ theorem, and is the backbone of statistical inference.
It can be applied to many questions and allows mathematical clarity in deciding the truth or falsehood of a question. For example: Do pink unicorns exist? Working on that question we would factor in such “evidence” as has a pink unicorn ever been seen? There are lots of depictions in children’s books and at Toys Are Us facsimiles abound. But have there been any pink Unicorn sightings lately? The answer is actually yes, but not often and by individuals whose credibility is in grave question, such as users of LSD or people that are experiencing delirium tremens. I leave the details of the calculations to you the reader, but it has been worked out by others that the likelihood of the existence of pink unicorns is about 10-17 plus or minus 2. Exponential numbers are difficult to wrap you head around especially if you are not a mathematician. To give you a feeling for that number let me make it more visual for you. 109 is approximately the number of grains of sand you can hold in your hands cupped together, while 1017 is the amount of sand that would fill the 2,000 Rose Bowels.
Now let us examine the likelihood of the existence of Santa Claus. Historically there actually was a Bishop by that name (Saint Nickolas – close enough) in ancient Asia Minor (Turkey) who did do good things especially for children and was in the habit of putting gifts into their shoes left outside in the month of December. Lots of children have seen Santa Claus and he even has an address at the North Pole honored by the US Postal Service. Working through the Bayesian formula and adding all the known evidence including the North American Aerospace Defense Command (NORAD) sightings of his sleigh on December 24th come out with the likelihood of Santa Claus’ current existence being 0.00000001%.
What about the question which the Holocaust Deniers bring up, did the Holocaust actually happen? According to the former President of Iran, Mahmoud Ahmadinejad, it is all propaganda. If General Dwight David Eisenhower, the supreme commander of the Allied Forces, had not held the opinion that without pictorial evidence no one would believe such cruelty and due to his foresight there are thousands of photographs of the atrocities of the Holocaust. Additionally, there are personal stories of victims and perpetrators, court documents and witnesses during the Nürnberg trials. Working our Bayesian formula, we come up with a 99.999999% likelihood that Mahmoud is wrong.
Now for a much harder problem, the existence of God. We must include such factors as the presence of man-made evil, of which there is plenty, and natural evil, which is ever present through tsunamis and earthquakes. If God were absent you would expect there to be lots of evil (as there is). Conversely, if evil were absent in the world, there would almost certainly have to be a God. We also must include the absence or presence of miracles, answers to prayers, God’s appearances on earth, etc. etc. We should include the Biblical testimony that God destroyed all life on earth with the Flood, all women, children (even the unborn), every man, all animals and plants. Speaking of Holocaust, that was the prototype and certainly should earn the title of “the Final Solution”. Hitler tried, but didn’t get anywhere near those numbers. What are the odds that an all benevolent, all powerful being would be involved with such a disgusting Fascistic solution to problems? What are the odds of the Master of the Universe, the Creator of all, to send his only son to a tiny planet, circling a medium sized star, located on the edge of one of the average galaxies of a total of 200,000,000,000 galaxies in the known universe? And there He picked an obscure region called Galilee. The purpose of this was to save mankind. Because of the tremendous distances involved he may have missed the fact that the majority of mankind was elsewhere, like North America, South America, Asia, Australia, and Africa. Or were those the lesser people that did not deserve saving? If God intended to send a message to mankind would you not expect it to be the best work of communication excellence that ever was? What are the odds that the message from the giver of life, the giver of justice, the giver of all, would send such a garbled, confusing, mixed message? Is it possible that the Almighty had no communications skills? Pythagoras was already in heaven (or the other place) by then. God should have engaged his services because his explanation of Geometry is about as clear as can be. There is only one Geometry. If God’s messages where just half as clear, we would not have over 4000 religions in the world, all claiming to be the true word of God.
If we honestly assess the available evidence and proceed with the calculation, unfortunately, the formula comes out with a devastatingly low number identical to the likelihood of the existence of pink unicorns.
Blaise Pascal (1623-1662), a French philosopher, posited that all humans bet with their future regarding the existence of God: He either exists or He does not. If you are on the “God is” side and you turn out to be right you gain an eternity of bliss. If you are on the other side, you risk an eternity of fire and brimstone. Pascal’s advice is to be on the side for existence because you have everything to gain and nothing to lose. The problem arises that it would be God, if He exists, we must credit with giving us the power to reason and using logic and tools like Bayes’ Theorem. We have calculated the odds of His existence to be 0.000000000000000001%, the same as the odds of the existence of pink unicorns. If you spend any time thinking about the existence of pink unicorns, you must reject such foolishness, and with the odds being so similar, by extension you ought to reject His existence as well. He should not have given us the power to reason or given us better evidence to plug into Bayes’ formula. It is His fault! Or is it just another one of his cruel jokes?