Wednesday, January 2, 2013
Sometimes, we reject a claim about reality because it doesn’t fit with other claims about which we have better evidence overall. Your aunt, who has smoked 2 packs of cigarettes a day for 20 years, is diagnosed with lung cancer. She has a job working in a building where there has been construction that has created a lot of dust over the last several weeks and she insists that it is the dust, not the smoking, that is the cause of the cancer. Or perhaps she, like millions of Americans, believes in hexes. And she’s suspicious that her neighbor across the street, with whom she has had a lot of personal friction over many years, has something to do with the cancer. The hateful thoughts radiating from the house across the street have made her sick, she thinks. In either case, the evidence we have for the smoking being the cause of her cancer is better, and with some thought and investigation, we could conclude with confidence that the smoking hypothesis is proven, and the other theories are disproven. Let’s call this Inductive Disproof.
A brief note about proof: Many people who haven’t reflected on the topic much have the sense that we should reserve the term “proof” only for those cases where we have the most substantial level of deductive certainty. We can prove, for instance, that 2 + 2 = 4, or that bachelors are unmarried. But we shouldn’t use the term proof for other matters of less confidence. Furthermore, their sense is that we should only use “proof” about indefeasible conclusions, claims that we would not change our minds about under any circumstances. For other matters, like smoking and cancer, the connection between a high calorie diet and obesity, and who won last year’s Superbowl, we should describe the status of our beliefs in some other way. And many of the same people who feel this way about proof have the same impulse about “knowledge.” We only know those things, they say, that we can prove. No other less certain matters should be called knowledge.
For a number of reasons, I think it is a mistake to reserve “proof” for only indefeasibly certain matters. First, if we raise the bar on “proof” this high, then there remains little or nothing that we know. On this view, we don’t know that smoking causes cancer, that the sun will rise tomorrow, that the sun rose yesterday, that Obama is the President, that violent crime is on the decline in the United States, that people who have a low fat, high fiber diet with lots of exercise tend to live longer than those without, and so on. Too many things that we comfortably and normally claim to know must now be described in some other artificial manner. Second, we can have our cake and eat it too; we can readily acknowledge that there are things we know and that we have proven, but our conclusion is defeasible. We can say that even though the evidence supports the conclusion overall, we are prepared, under the right circumstances, to change our minds in the light of new information. We know that the force of gravity, for instance, on the surface of the Earth is 9.8 meters/sec2. (The extreme proof/knowledge advocate must insist awkwardly and artificially, “No, we don’t really know that, we only have a massive amount of evidence and justification for it.”) A more natural way to proceed here is to say that we know, and have proven, many things beyond the deductively certain. But we are always ready to incorporate new evidence into our theories about what is true and change our minds if that becomes warranted. Third, people who press for the extreme proof/knowledge view are quite vulnerable to the Going Nuclear problem. Fourth, the extreme proof/knowledge view often fall into the Sliding Scale Fallacy. And fifthly, to make the extreme proof/knowledge advocate happy, we can easily make a distinction that is widely accepted and acknowledged in the sciences between inductive and deductive proof/justification.
Now back to varieties of disproof. Sometimes we reject a claim because it is internally inconsistent or logically contradictory. We know that Smith is not a married bachelor for instance, or that a three sided figure labeled ABC is not a square, because married bachelors and three sided squares are logically impossible. Deductive disproofs of the existence of God in this category have either argued that a single attribute that is typically given to God like omnipotence is impossible, or that some combination of properties like infinitely just and infinitely merciful are mutually inconsistent. Let’s call these Single Property Deductive Disproof and Multiple Property Deductive Disproof. There is an an extensive philosophical literature stretching across centuries offering these sorts of disproofs for God. See:
Sometimes we reject a claim because the concepts that it employs and the model of reality that is embedded in the concepts has become impoverished, bankrupt, useless, or inapt at describing reality. Consider three theories about a sick person who is exhibiting swollen lymph nodes, gangrene, fever, malaise, and seizures.
He might be possessed by evil demons, he might have an imbalance in his four humors—black bile, yellow bile, phlegm, and blood—that could be rectified with leeches, or he might have a bacterial infection of yersenia pestis—Bubonic Plague. The Bubonic Plague theory along with modern virology in which it is embedded turns out to be far better at recognizing the ailment, treating it, curing it, preventing it, making predicitions, and so on. If we successfully cure the patient by means of virology and the Bubonic Plague hypothesis, it’s not so much that we have disproven the evil demon possession claim in any deductive or logical sense. It’s still logically possible that there could be evil demons disguised at the yersenia pestis bacteria in his blood. But holding onto the evil demon claim and the baggage that comes with it just becomes increasingly useless, and extraneous in our model of reality.
At some point we leave some ideas behind because they just don’t fit with the rest of what we know about reality. It strikes me as natural and sensible to say that we know that those symptoms are caused by yersenia pestis now. We have proven that the illness is caused by the bacteria, and not by evil demons. Let’s call this sort of case Theoretical Disproof.
So on this way of carving things up, we have at least fours kinds of disproof: Inductive Disproof, Single Property Deductive Disproof, Multiple Property Deductive Disproof, and Theoretical Disproof. There are others, and there are different ways of mapping out the epistemological landscape. But this will suffice for now.
As I see it, the God hypothesis, where God is described in the ways that the vast majority of modern believers describe him, fails because of arguments of all four types. More details about can be found in the over 300 posts on this blog written over the years, in my recent book Atheism and the Case Against Christ, and in the book I’m now working on Atheism: Proving the Negative. There are some other accounts of God that escape those four varieties of Atheological Disproof, but those, as far as I can tell, just end up being vaccuous, trivial, or unmotivated—God is love, God is the development of human self-awareness, God is energy, God is reality.
So the challenge for the theist, as I see it, is to first come up with a description of God that is internally, logicall coherent. It must attribute properties to God that are individually coherent, and that are logically consistent with each other. And this description must navigate around the broad set of Deductive Atheological arguments that have undermined the God concept. Furthermore, the description needs to it needs to be sufficiently superlative to warrant the "God" label," and, one would hope, it would have some semblance to the supernatural being that billions of traditional believers have advocated for centuries. Then the theist reconcile the claim that this being is real with the a posteriori facts as we know them—the theist must deal with the Inductive Disproofs for God. The theist needs to address the problem of evil, the problem of divine hiddenness, and a host of other serious inductive challenges that have come up over the centuries.
But even all of that wouldn’t be sufficient to justify theism, as I see it. We could construct some account of evil demons that is internally logically consistent. And we could add enough provisos, tweaks, and emendations to the story to accommodate all of the details of modern virology. Evil demons are clever and sinister, you see, and part of their malevolent deception of us is that they are disguising their activities to look like bacterial infections, cancer, and so on. How do you know, afterall, that viruses and bacterial infection aren’t just the way that evil demons do us harm? Like evil demonology, theology has been rendered superfluous and vacuous by the rest of what we have learned about biology, geology, history, psychology, anthropology, astronomy, and cosmology.
The theist, as I see it, has to do more than sketch out some scheme whereby it might be possible that God employed evolution to create us, for example. The theist needs to give us some substantial positive evidence for thinking that it is true. Possible, as I have argued many times, it not probable or reasonable or justified.
Are we proving the negative yet?
Posted by Matt McCormick at 8:24 AM