Dec 02

How to use Bayes’ Theorem

Recently, I wrote a Bayesian formulation of Carl Sagan’s famous maxim, ‘Extraordinary claims require extraordinary evidence.’ However, since the aim of that post was not to teach Bayes’ Theorem, but to reply to a criticism of the maxim, I may have left readers unprepared to actually use this theorem. I thought it might be helpful to provide an explanation. The equation looks difficult, but it’s actually quite simple once you understand the symbols. It’s just a matter of figuring out a few numbers.


Bayes’ Theorem

Here is one way to formulate Bayes’ Theorem when you want to know the probability of A given B:

Since A and B might sound a little abstract, let’s provide a concrete example and we’ll walk through the equation step-by-step.


Breast Cancer

Eliezer Yudkowsky uses the following example[i] that most doctors get wrong when polled:

1% of women at age forty who participate in routine screening have breast cancer. 80% of women with breast cancer will get a positive mammography. 9.6% of women without breast cancer will also get a positive mammography. A woman in this age group had a positive mammography in a routine screening. What is the probability that she actually has breast cancer?

So, we want to find the probability of breast cancer (A) given a positive mammography (B). We will just need to concern ourselves with four figures—the two in the red box (the numerator is repeated exactly in the denominator) and the two in the green box. These four figures are:

  • P(B│A) = the probability that you will have a positive mammography if you have breast cancer
  • P(A) = the probability that you have breast cancer prior to considering the evidence, which is why it is often called the ‘prior probability’
  • P(B│¬A) = the probability that you will have a positive mammography if you do not have breast cancer
  • P(¬A) = the prior probability that you do not have breast cancer

So, now we should be able to figure out where to plug in the numbers from the initial problem:

  • P(B│A) = 0.80
  • P(A) = 0.01
  • P(B│¬A) = 0.096
  • P(¬A) = 0.99

The last figure of P(¬A) was not explicitly given above, but we can always figure it out if we know P(A). That’s because P(A) + P(¬A) = 1. Think of it this way: 1 is the total amount of possible probability to be divided up among options because 1 is really the same as 100%. So, whatever the probability is that A is true, it is necessarily the case that the probability that A is not true completes whatever is left to add up to 1. If there is a 70% chance that A is true (0.7) then there is a 30% chance that A is not true (0.3). In this particular case, the prior probability of A was 1%, so the prior probability of ¬A is necessarily 99%.

Now that we have our numbers matched to the terms, we can return to the original formula:

P(A│B) =   0.80*0.01_____________

(0.80*0.01) + (0.096*0.99)

Simplified further, it reads:

P(A│B) =   0.008____________

0.008 + 0.09504

P(A│B) = 0.0776

This means that if you are a woman at age 40 and receive a positive mammography, there is actually only a 7.76% chance that you have breast cancer. Only 15% of doctors across several surveys gave the correct answer. Most of them replied that there was an 80% chance that you have breast cancer in this scenario. That’s quite a difference, especially to the woman wondering whether she has cancer!


Belle and Gaston

That problem is relatively easy, since you are given the numbers. What happens, though, in a fairly ambiguous situation where estimation is required?

Let’s say that Gaston has approached Belle for a date and been rejected on multiple occasions. He is trying to determine whether Belle really likes him and is playing hard to get or whether she genuinely does not like him. So, we are looking for the probability that Belle likes Gaston (A) given the evidence of her repeated rejections (B). Again, we will just need to concern ourselves with four figures, tackled one-by-one:

  • P(B│A) = the probability of rejections if Belle likes Gaston

We can recognize that the first figure should be quite low, given that Belle is known to be a very honest and straightforward person. If Belle actually likes Gaston, we would expect an honest admission of this, rather than repeated rejections. However, women can be funny in showing their affection, so I would say it’s still greater than 0. Let’s place the probability at 0.05. It’s very low, but leaves a little room for error in case our perception of Belle has been mistaken.

  • P(A) = the prior probability that Belle likes Gaston

The second figure should be high, given Gaston’s popularity with women in general. Remember that in factoring this number, the evidence, such as the rejections, should not count. In other words, there is no B in this part of the equation. So, let’s err on the side of Gaston’s prominent features—good looks, size, fighting ability, egg consumption—and place the probability at 0.9.

  • P(B│¬A) = the probability of rejections if Belle does not like Gaston

The third figure should be very high for the reasons previously discussed about Belle’s honest manner. If Belle does not like Gaston, then it is almost certain she would reject him. Let’s place that probability at 0.99.

  • P(¬A) = the prior probability that Belle does not like Gaston

Finally, the last figure is 0.1. Remember, it is simply filling out the remainder from P(A).

So, now we can plug in the numbers:

P(A│B) =   0.05*0.9____________

(0.05*0.9) + (0.99*0.1)

Simplified further, it reads:

P(A│B) =   0.045____________

0.045 + 0.099

P(A│B) = 0.3125

Even though Gaston finds himself desired by women in the overwhelming majority of cases, the evidence here is such that he can be confident that Belle does not like him. There is only a 31.25% chance that she does in fact like him (A) given her rejections (B).



If you came into this not knowing much about Bayes’ Theorem, hopefully you now understand it a bit more. The math involved here is really not that difficult. You simply have to determine four numbers and then just let the formula do the heavy lifting. I would recommend plugging in some numbers to see what happens to the outcome. For example, when you have really high or low prior probabilities, it’s hard to overcome them with evidence. This was the essential point in my earlier post about extraordinary evidence.


[i] If you want to dig into the details more, he gives a really nice, in-depth explanation with lots of examples here:


Nov 29

The hiddenness argument revisited (II) by J.L. Schellenberg

In an earlier post, I outlined the argument from hiddenness by J.L. Schellenberg along with his responses to several criticisms of the argument. These criticisms were grouped together in virtue of being irrelevant, according to Schellenberg. They generally were either already covered by one of his premises or could be explained away by further clarification.

In this post, I’ll explain Schellenberg’s second article that covers criticisms he does find relevant. This should be quite simple to understand since he recommends using the same general approach to every such criticism. He calls this approach the Accommodationist Strategy (hereafter, AS). AS may need slight tailoring in each case, but the overall structure will be the same.

So, what is the AS and how does it work? Essentially, the AS works by placing an enormous burden of proof on the opponent who claims to have a defeater for the hiddenness argument. Such defeaters include offering a reason for the hiddenness (we’ll see one example). When presented with a reason for hiddenness, ask yourself whether the proposed good brought about by it can be achieved by any other means that does not result in reasonable non-belief. Remember that God is all-knowing and all-powerful, so can really use any means for achieving his ends. As Schellenberg says, “It comes up against the unsurpassable immensity of divine resourcefulness.”[i]

Let’s look at one quick example. Swinburne, in Providence and the Problem of Evil, argues that certain goods, like responsibility, flow from not having a constant or immediate knowledge of God. But can such goods, Schellenberg asks, really not be derived by any other means at this immensely resourceful God’s disposal? The fact that we can come up with ways to do it ourselves with all of our limitations would strongly suggest that God could indeed derive them in other ways. Schellenberg says these are just tokens of certain types of good. There are other ways to actualize the types of good without hindering a relationship with God. A perfectly loving and relationship-seeking God would necessarily prefer these other tokens, if available.

Similarly, the AS can be applied to soul-making and other relevant criticisms that posit some type of good achieved by hiddenness.


Further Thoughts

Since that strategy should be grasped pretty easily, I thought I’d include some bonus material for responding to reasons given for hiddenness. Atheist philosopher Stephen Maitzen, whose arguments I highly recommend, poses another difficulty for such objections. While Schellenberg’s AS makes it difficult to establish said criticisms as defeaters, we still might wonder how well they work as undercutters.[ii] I think Maitzen’s response to such criticisms gives us good reason to think they don’t even work well on that front. Maitzen argues that any explanation for hiddenness will have to also account for the geographic distribution of theistic belief and non-belief. For example, Afghanistan is almost uniformly theistic and Cambodia the opposite. If we assume that the reasons given for hiddenness are at work, then it’s hard to see why religion should be geographically distributed in a way that makes more sense under naturalistic explanations.

[i] “The hiddenness argument revisited (II)” p. 288.

[ii] A defeater renders a premise false outright where an undercutter renders it less probable.

Nov 23

Extraordinary Claims Really Do Require Extraordinary Evidence

Yes, it’s still true. The basic principles of mathematics and probability have not changed. Thus, it is surprising to read an article saying that requiring extraordinary evidence for extraordinary claims doesn’t make sense. At least, it’s surprising until you realize the person making the claim is probably an evangelical Christian with an extraordinary claim to promote. So, how should we respond? I’ll provide a short answer and a long answer.


The Short Answer

Bayes’ Theorem, which has been proven to be formally valid, tells us that extraordinary claims (things with very low prior probabilities) do indeed require extraordinary evidence. For example, imagine my friend tells me he won the World Series of Poker. I would first be struck by the improbability of such a claim considering the Main Event has over 6,000 entrants and this particular friend isn’t that good at poker. Even so, it’s not impossible and there is evidence which would overcome that initially low probability. Examples of significant probability-raising evidence would include if he had millions of dollars suddenly and if he had a WSOP bracelet. If you want to see this idea demonstrated mathematically, keep reading. 


The Long Answer

This is Bayes’ Theorem:

P(h|e.b) = P(h|b) x P(e|h.b)  /  [ P(h|b) x P(e|h.b) ] + [ P(~h|b) x P(e|~h.b) ]


Symbol Meaning
P Probability
H Hypothesis
E Evidence
B Background Knowledge
| Given
~ Not (or the negation of)
. And


In English, this says, “The probability that a hypothesis is true, given available evidence and background knowledge is equal to [and then you have the equation].” To understand the equation, let’s dig into the details just a bit.

The first term you’ll notice once you read past the = symbol is P(h|b); this is the prior probability. This term is concerned with the probability that a hypothesis is true given your background knowledge. So, when we say that the virgin birth has an incredibly low prior probability, that means that based on everything we know about the world through science, history, etc. this sort of thing doesn’t generally happen. Quite simply, we understand how babies are made, and this isn’t it. Further, in cases where parthenogenesis does actually occur in other animals, the resulting offspring are always female. So, if true, this would seem to be a one-time thing. I have no idea how many humans have ever existed, but let’s say there have been 100 billion. This would make the prior probability 1/100,000,000,000. Note that this is prior to considering any evidence for the case in question, hence the term prior probability.

The second term above is P(e|h.b), meaning the probability that you would have the available evidence given your hypothesis and background knowledge. In other words, would the available evidence be expected under the hypothesis? For example, say someone claims they’ve been to the beach for the past few hours. You notice they are sunburned and in their car is a beach towel. These things fit the claim well and would merit a high number. On the other hand, the lack of sun kissed skin and a movie ticket stub from two hours earlier would not be the sort of evidence you would expect.

This covers the numerator. It is the prior probability multiplied by the likelihood of the evidence.

Now, as you keep moving from left to right, you’ll notice that the first term in the denominator is the entire numerator repeated. That’s why the theorem is sometimes shortened to P = A / A + B. So, what is B? It is basically the same as discussed above, only for ~H, rather than H. It is the probability that your hypothesis is false and the likelihood of the available evidence given a false hypothesis.

Let’s plug in some numbers using a very low prior probability and see the earlier claim in action.

  • P = 0.01 x .9 / (0.01 x .9) + (0.99 x .75) = 1.2%

Here we see a low probability event where the evidence is almost nearly as well explained by negating hypotheses and the probability is slightly raised, but remains very low. Now, let’s slowly decrease the likelihood that the evidence can be explained by alternative hypotheses and watch what happens to the outcome.

  • P = 0.01 x .9 / (0.01 x .9) + (0.99 x .50) = 1.8%
  • P = 0.01 x .9 / (0.01 x .9) + (0.99 x .25) = 3.5%
  • P = 0.01 x .9 / (0.01 x .9) + (0.99 x .10) = 8.3%
  • P = 0.01 x .9 / (0.01 x .9) + (0.99 x .01) = 48%

We don’t see a substantial increase in probability until we get into very low ranges of likelihood for the same evidence to be observed on alternative hypotheses. In the last example, there is only a 1% chance that the evidence can be explained by alternative hypotheses. In cases of low prior probability, the evidence must be such that it basically rules out alternative hypotheses to a very high degree.

In other words, extraordinary claims really do require extraordinary evidence.


Nov 10

The Lazy Person’s Guide to Dismantling the Moral Argument

I once was part of a comment thread where theists were asked what their favorite arguments in favor of God’s existence were[i]. The argument that seemed to stand above the rest by my informal count was the so-called Moral Argument. If you’re not familiar with this argument, it goes as follows:

1. If God does not exist, then objective moral values do not exist.

2. Objective moral values do exist.

3. Therefore, God exists.


Many are inclined to object to (1) on the basis of some secular theory providing an objective grounding for morality. I have done this in the past by appealing to contractualism. However, this turns complex very quickly and it’s notoriously difficult to gain agreement. I think there is a better way to dismiss the argument. By disputing (2), we can show that the argument does not actually give us reason to conclude anything. In fact, we can do this very simply as follows:

4. The justification for (2) is that everyone has an experience of morality.

5. Either this experience can be explained in natural terms or it cannot.

6. This experience can be explained in natural terms.

7. Therefore, natural explanations are sufficient to account for (2).


Basically, we are left with these possible scenarios, if a successful natural explanation can be given:

S1: The natural explanation is true and is sufficient to ground objective moral values

S2: The natural explanation is true, but is describing something that does not ground objective moral values


Under the first scenario, we affirm (2) and reject (1). Under the second scenario, we reject (2). Either way, the premises of the initial moral argument fail to support its conclusion. Since either scenario accomplishes this, we can forget about (1) altogether! All you have to do is support (6) by saying that our experience of morality can be explained naturally. This sidesteps the very thorny issues of metaethics[ii].

So, is (6) well supported by scientific literature? I think so. Two popular-level examples that come to mind are Marc Hauser’s Moral Minds: The Nature of Right and Wrong (P.S.) and Michael Shermer’s The Science of Good and Evil: Why People Cheat, Gossip, Care, Share, and Follow the Golden Rule. These tell an evolutionary story about morality, which I think is probably on the right track. You might even prefer a simpler argument that our experience is just a ‘gut’ reaction to things we find pleasurable, distasteful, etc. I can see a compelling argument being made with that approach too.

Thus, we have a very simple dismissal of many theists’ favorite argument.


[Cross-posted at An American Atheist]

[i] They were also asked which arguments they most feared against the existence of God. Problems of evil seemed to be the main stumbling block.

[ii] Any objections to (6) on the grounds that the explanation wouldn’t make something really wrong are strictly irrelevant. This would be an attempt to steer you back to the metaethics, but this argument does not require any position on that front. If you can provide good evidence for your explanation, then they have to disprove it before anything can be concluded using the moral argument.

Nov 03

Skepticon IV Conference

Skepticon IV will take place November 19 – 20 in Springfield, MO:

There are some fairly big names as speakers, including Richard Carrier, PZ Myers, Dan Barker, Hemant Mehta, Eliezer Yudkowsky (nice!), Spencer Greenberg, David Silverman, and many others.

The event is billed as the largest conference of its kind in the Midwest. It’s a free event and should be a good time, considering you probably don’t find yourself surrounded by other atheists too often. I will be attending, so anyone who wants to have a beer or anything should let me know.

Here are some things that stand out to me as promising:

  • The day before the conference (Friday), there will be a group trip to The Creation Museum of the Ozarks
  • Eliezer Yudkowsky’s presentation
  • Richard Carrier’s presentation on Bayes Theorem, which is subtitled, ‘that’s right, I’m teaching you math, bitches!’
  • Spencer Greenberg’s presentation

You can register here. I hope to see you there!

Oct 27

Many Worlds and Ultimate Justice


Here is a strange progression I just went through in my car.

Suppose something like Everett’s many worlds hypothesis is correct. Under this, every possible outcome is equally real. There is a you reading this right now, a you who decided to eat a sandwich instead, and perhaps infinitely many other yous.

It struck me that this seems to make punishment for free choices unjust, since some version of you has to make that choice.

But then I considered that a theist might reply that all of these do make a choice. God simply would be rewarding all of those choices that were good and punishing those that were bad. So perhaps I would go to Hell in this world, but Heaven in another.

Finally, though, it occurred to me that there are many more ways to fail to please God than to succeed. So, an overwhelming percentage of the possible yous would go to Hell. This seems unjust since all of the possibilities would necessarily be carried out in the many worlds scenario.

And just as I write that last paragraph, I wonder if this supports Plantinga’s idea of transworld depravity and perhaps we’ve just come full circle. I have no idea what to make of quantum mechanics and the idea of God.

Oct 17

The hiddenness argument revisited (I) by J.L. Schellenberg

Graduate students in St. Louis have recently formed a reading group for philosophy of religion. Unfortunately for me, it conflicts with my work schedule, so I can’t join them in person. I’m going to read along, though, and I’ll provide a summary of each reading.

This week’s reading is “The hiddenness argument revisited (I)” by J.L. Schellenberg, a Canadian philosopher whose work on justifying skepticism has been very influential[i]. Schellenberg wrote an important book called Divine Hiddenness and Human Reason. This paper, done in two parts, is a response to critics of that book. In Part I—the focus of this post—he is responding to a group of criticisms that he views as irrelevant, and then in Part II he considers the “relevant” criticisms.

The Argument

Let’s begin by recapping the initial argument from his book. In this paper, Schellenberg does not provide a helpful numbered syllogism, but I think we can condense what he takes a few pages to say as follows:

1. There is a personal and perfectly loving God.

2. There are creatures capable of having a relationship with this God.

3. A perfectly loving God would not act to hinder this relationship.

4. Belief in God is a necessary condition for a creature to enter into this relationship.

5. Creatures capable of this relationship that do not resist God will always have this belief.

6. Yet, there exists reasonable non-belief.

Premise (1) should just be considered granting for the sake of argument that a traditional version of God exists with these properties. Premise (2) also ought to be granted by theists, as they probably consider themselves as having such a relationship.

Premise (3) is not suggesting that God would or should force a relationship, but that he would not prevent an honestly sought relationship. He supports this with a nice analogy: A parent may step aside and allow a child to take responsibility, but this is always done within the context of a relationship. The child knows they exist, they have had experience with the parent, and they know the parent wants the relationship to continue. Even if the child doesn’t want a relationship, the possibility of contact and restoration is still there.

Premise (4) seems reasonable to me, as well. I cannot imagine trying to enter into a relationship with someone or something I don’t believe exists. For example, let’s say you find out one day that a friendly colony of intelligent sea creatures lives under the ice of Europa. Would it make sense for someone to criticize you for not doing anything to help these creatures? No, you had no idea they existed, so what would prompt action on your part?

I think Premise (5) can be clarified to say that these creatures will always have sufficient evidence to produce a belief in God. Basically, Schellenberg wants to say that God would make this sufficient evidence available so that anyone honestly seeking it will find it. By that rationale, anyone capable of honestly seeking God will believe in God.

And yet, there are people who have honestly sought and have not found. Or there are people who have never heard of this God, so, while they have not sought, they have also not rejected. This does not mean that everyone must actually respond to this evidence and have a relationship with God. Schellenberg says, “The reasoning developed in support of the idea that God would facilitate relationship and (therefore) prevent reasonable non-belief leaves plenty of room for non-actualized relationship with God, claiming only that such relationship will be available in the absence of our culpable resistance if a perfectly loving God exists.” So, (6) does not depend on every non-believer being a case of reasonable non-belief. It merely requires that there is at least one case. Thus, to deny (6) strikes many people as implausible and would probably require one to beg the question. You might be able to paint a large group of non-believers with the brush of rejecting or hardening their hearts toward God, but could you seriously say that about every non-believer there has ever been?

If we work backwards, we can see the problem. If there are reasonable non-believers, then there is not sufficient evidence for belief. If there is not sufficient evidence for belief, then there is not a relationship-seeking, perfectly loving God.

Some Objections

Schellenberg considers several objections, but I’ll just outline a few major ones for the sake of brevity.

A: The first objection considered, and perhaps the most popular one, is that this is merely an atheistic demand for signs and wonders to be performed. I have argued before that such signs and wonders are actually quite prevalent in the stories of Christianity and other religions. But Schellenberg wants to simply dismiss the objection as irrelevant since the argument only requires evidence that will be accepted unless there is resistance. There is no need for burning pyres or changing the chemical composition of liquids, even though these things are alleged to have happened.

B: I’ll be honest that I don’t entirely understand the second objection considered. It says that God may have reasons for withholding evidence from inculpable non-believers. The argument claims that God waits for non-believers to show that they are well-disposed for belief prior to revealing himself. Schellenberg describes it as saying, “There may be inculpable non-believers who, embittered by suffering, would reject God if they came to believe that God exists.” Said in that way, I can see why he rejects it as irrelevant. The argument allows for people to reject God by their own fault, just as the father allowed his prodigal son to take his inheritance and leave. But God’s existence and his desire for the relationship should be made known, just as the same. The prodigal son returned, after all.

C: A third problematic objection says that belief is not necessarily strongly correlated with this type of relationship. That, however, is unimportant. The belief is used in the argument as merely a necessary, rather than sufficient, condition. There must be a belief, in addition to other things, in order to prompt the action of entering into a relationship.

D: A fourth objection seeks to equate God with an abstract conception of the Good and permit a sort of Universalist interpretation. This means that anyone responding to “the Good” is responding to God, even if they define it in some other way. Schellenberg says this criticism does not meet his criteria head-on, as he is talking about the type of reciprocal relationship many theists claim to have.

E: A fifth objection says that God is so incomprehensible that it would be impossible to completely eradicate reasonable non-belief. Presumably, there would always be at least one reasonable non-believer. Again, this argument is for a God other than the one defined by Schellenberg. He seeks to argue against is the traditional conception of God. Many people do think you can know this God well enough to enter into a relationship.


Schellenberg thinks, for the reasons given, that these objections do not really interact with the hiddenness argument as presented. They either provide objections that have already been considered by the argument’s phrasing and defense or want to defend a different conception of God.

So what objections does Schellenberg think are relevant and how does he respond? I’ll cover those next week when I discuss Part II.

[i] I’m not going to attach a copy of the paper to avoid any potential for liability. However, if you want a copy of the paper for personal use, email me using the contact form on this site.

Oct 08

The Parable of the Great King

A boy of nearly six lay weeping on the side of the road. His father, face down in the mud beside him, had just been slain. He was unable to pay the taxes required by the local governor. He pleaded with the collectors to spare his life, as he had no money with which to pay them. This was not their concern. The man was killed; the debt passed to his son.

A woman who witnessed the event came to comfort the boy. “I know this is hard for you to understand now,” she said, “but the King has a plan for all of us.”

The boy had heard of the King all his life, but had never seen him. No one in the town had. But everyone knew the stories. The King was a great man—powerful and wise. He was kind and loving and gave selflessly to help his people. He was even a great healer. The world had never known a greater ruler.

The boy knew the King was great, he’d been told so by everyone, but he couldn’t shake the vision of his father being cut down in the street. “How could the King let this happen?” he asked the woman.

“Child,” she said with pain in her eyes, “my own son was about your age when he was taken by the sickness. I’ve lived with that pain for 30 years, but I have faith in the greatness of our King. If there is suffering in his kingdom, he must have some reason for allowing it. Don’t you know the story of The Terrible Conquerors?”

“Yes, of course” the boy replied. “They invaded our lands until the King drove them away.”

“So, don’t you see? If the King saved his people from that evil horde, then we know he does act to prevent injustice. He shows himself and provides evidence of his greatness and power, but only at certain times.”

“But why couldn’t he help this time? It’s just as good as any! My father searched for work every day, but there was none. He didn’t have any money to give,” cried the boy.

“We must have faith in these circumstances. The King always knows what happens in his kingdom, so there must be some higher reason,” explained the woman with compassion. “Otherwise, it would mean the King is not great and loving.”

The boy turned back to his lifeless father. Tears overcame him once again.

Oct 04

The Problem of Heaven

For those of you who don’t know, I also contribute to a group blog called An American Atheist. I have a new post there that you might find interesting – The Problem of Heaven.

Oct 03

How Warranted is Properly Basic Belief?

This is a guest post by Matt DeStefano, and is part of the continued series Why Christianity is False. You can read more of Matt’s work at Soul Sprawl. In order to keep discussion under one heading, please visit the original piece here to comment.


This is in response to Dr. Matthew Flannagan’s essay Showing Christianity is True. I’ve previously written a response to Dr. Flannagan in my post When Christians Play the Part of Skeptics, and when we were deciding as a group which articles we wanted to tackle, I happily picked a name I recognized. Flannagan is easily one of the best thinkers of the bunch, and I was certainly interested in the topic of his essay: the epistemology of religious belief, and more specifically, reformed epistemology. If you haven’t already read it, I would definitely take the time to peruse the article and then you can understand where my critique is coming from.Flannagan begins by laying out a few questions that seem to have intuitive answers: Are there other minds? How do I know the Universe wasn’t created Last Thursday with the appearance of age? How do I know it’s wrong to inflict pain on others? He continues by saying:

Unless we want to fall into a global scepticism that defies all common sense we have to acknowledge that there are some beliefs which we hold rationally and know are true that, nevertheless, cannot be shown or proven to be true from premises that all intelligent people are required to accept.

I’m curious as to how Flannagan is using the term “proven to be true”. He seems to be setting the bar at deduction: unless we have a valid deductive proof with premises that “all intelligent people are required to accept”, then we cannot accept things as true. Or, rather, we can rationally hold these beliefs to be true without argument or evidence. This is a key move of the reformed epistemology movement, and one I think is gravely mistaken. This is a radical epistemological stance that seems like a carryover from Cartesian foundationalism. It seems that philosophers and scientists make claims of knowledge that aren’t deduced from a valid logical argument. We seem to know things like exercise increases overall health, alcohol consumption causes liver damage, and nicotine is an addictive substance. Perhaps Flannagan’s answer to this would be that we could only know these things by properly basic beliefs (the physical world is real, cause and effect, etc.), but it’s interesting that under this type of skepticism, he would have to conclude we don’t actually know those things.

Flannagan moves on to say that even though these can’t be proven true by argument, they aren’t groundless. He quotes Platinga and distinguishes between two types of experiences and “evidence” that lead us to ground our properly basic beliefs: sensory data evidence and doxastic evidence. Sensory data is fairly self explanatory: experiences we get from touch, sight, hearing, and all of the other senses we use to interact with the physical world.

Doxastic evidence is a bit of a queer category: he quotes Platinga again as saying that doxastic evidence is when “the belief feels right, acceptable, natural.” This seems to be the type of evidence that leads Flannagan to what I gather is his thesis:

Belief in the existence of God is, from the believer’s perspective, properly basic and grounded directly in some form of religious experience; hence it is justified and rational to believe these doctrines independently of any argument in favour of them.

This immediately raises a hundred different red flags in my mind. How do we know that our beliefs aren’t what are causing us to have a religious experience? How do we characterize that religious experience as one relating to Yahweh rather than Zeus or Thor? How do we know the difference between when we have a religious experience and when we are being delusional? What types of “feelings” are required in having a religious experience? These are things you’d expect someone defending the idea of a properly basic belief grounded in religious experience to address.

Nisbett and DeCamp Wilson, in their landmark Telling More Than We Can Know: Verbal Reports on Mental Processes have shown our remarkable inability to properly account for causal effects on our behavior. It’s odd to me that Flannagan and other reformed epistemology advocates place so much emphasis on our ability to introspect and not only confirm the character of the experience (religious or otherwise), but purport a causal relationship between that experience and the Christian God simply by examining our own feelings regarding our experiences. Is this really the only basis required for properly basic belief?

However, Flannagan skips over this seemingly vital defense and continues by addressing a slightly different question: How can we convince people that haven’t had these doxastic experiences that Christianity is true? Flannagan lays out a few different possibilities:


1. Rebutting Objections to Christian Belief

Flannagan points out that while you need not give argument for your belief in Christianity (Can you imagine an atheist saying ‘I have a properly basic belief that there is no God!’), it does not mean that Christianity cannot be defeated by reasons against them. However, providing an “out” for Christian belief no more convinces me of its truth than Russell’s justification for his celestial teapot convinces me of its truth. In fact, the more wild and improbable the defenses become, the more inclined I become to dismiss it entirely.

It also stands that Christianity has gone under significant changes through out its history, and has an enormous amount of doctrinal change and fracturing. Which Christianity do we need to object to? What prevents the apologists from just moving back the goal posts everytime a significant part of Christian doctrine is rebutted?


2. Showing Alternatives to Christianity to be False

He states that if you can illustrate that all of the viable alternatives to Christian theism are false, then you have a valid reason for accepting Christianity as true. Of course, this becomes an increasingly hard task when you have to compare religious ideologies. What metric do we use to determine what qualities of God are actual, and which ones are merely accidental byproducts of a flawed human conception?

Ironically, the skepticism that RE is built upon vanishes when we begin talking about other worldviews.


3. Reason Conditionally as a Christian

Flannagan says that if you reason conditionally as a Christian, you can provide “satisfactory” answers to existential, moral, and other types of questions. This isn’t a small debate, but I think Christianity fails to answer some of its most basic internal questions, let alone external questions. In fact, a large portion of atheist writing is actually aimed at showing how badly the Christian metaphysical system answers questions about reality.

Actually arguing those positions goes beyond the scope of this essay, but all over my site and other atheists’, you can see arguments as to why theism fails to explain basic tenets of the universe, or even basic internal convictions of theism itself.


4. Put that Person in a Position to have Requisite Experience

Flannagan makes an extremely peculiar analogy:

Suppose I see a tree in the park and my wife asks me to show her that this tree exists. The obvious way to do so is not to construct a proof of the existence of a tree but to take her to a park and show her it. Similarly, many people fail to grasp self-evident axioms of logic because they fail to understand them, but when these are explained to them they become self-evident.

This rests upon the claim that God is as self-evident as logical axioms, or trees existing in the park. If a theist could simply bring me to a church and point to God, the God thesis would be much less controversial. Those comparisons are far too generous, and I think even Flannagan would deny their relation if pressed further. The amount of detractors who were sincere believers before their deconversion serve as strong counter examples to the existence of God (or a ‘requisite religious experience’) being as self-evident as touching a tree in a park.

Apparently, if a person goes to church where “God is at work”, and reads Scripture, interacts with other Christians that this will put them in a place where they might have a requisite religious experience. So, immerse someone in a culture and they might adopt its tenets. It’s no secret that churches use this method all of the time. Unfortunately, this method smacks of cultism. If you brought someone to a Scientology compound, it’s possible that they might after considerable immersion begin to buy into the ideology. But, should we gather from that conversion that Scientology is true? Absolutely not.

Flannagan brings up Pascal, saying that while the agnostic simply cannot choose to believe (a concession many Christians don’t realize), he can choose to search, to try and understand, and when the agnostic does so sincerely, he will come to experience God. But, this reaches back to what I called the vital defense of reformed epistemelogy: give me some reason to suspect that these doxastic experiences are from God. Otherwise, I think it’s more reasonable to just assume I’m experiencing hyper-active agency detection or delusions.


Older posts «

» Newer posts