Justified True Belief

(●) An appeal to ignorance treats a claim as true because nobody has disproved it, or false because nobody has proved it. + The Latin is argumentum ad ignorantiam, "argument to ignorance", and the name is exact: what nobody knows is made to do the work of a reason. It runs in both directions. (1) The shape of the move is a conclusion drawn from an empty place. - At a parish council meeting a woman says the new phone mast is making the children ill. Asked whether anyone has shown that, she answers, "Has anyone shown it isn't?" Nobody has. And so, she concludes, it is. - Two words help here. The reasons someone offers are the premises, and what they are meant to support is the conclusion. Her premise is that nobody has proved the mast safe. Her conclusion is that the mast is harmful. - Between the two there is nothing. Nobody has tested the mast, so the silence she points at is what you would hear whether the thing is dangerous or perfectly harmless. - Textbooks such as Hurley's file the move among the fallacies of weak induction: arguments whose premises bear on the conclusion, but far too lightly to carry it. An unfinished search is not nothing. It is just not a verdict. (2) It tempts because sometimes an empty search really does settle things. - You open the fridge, see no milk, and conclude there is no milk. Nobody calls that a fallacy. Milk is the kind of thing you would see if it were there, and you looked where it lives. - The fallacy is treating every empty search like the fridge. "Nobody has proved there is no life under the ice of Europa" tells you nothing about Europa. Nobody has been to look. - There is a second pull. "Nobody has proved otherwise" hands the work of proof to somebody else. That is restful, and restful is what makes the move so common. (3) The name is Locke's, and the family has three cousins. - John Locke put argumentum ad ignorantiam into print in 1690, meaning something different by it than we do: pressing an opponent to accept your proof or produce a better one. Douglas Walton's Arguments from Ignorance (1996) is the standing study, and it finds the move often reasonable and only sometimes a fallacy. Telling the two apart is the whole job. - God of the gaps fills a hole in scientific knowledge with God. "Nobody knows what caused the Big Bang, so God did." The chemist Charles Coulson made the phrase famous in 1955, a Christian warning Christians off it. - Personal incredulity fills the hole with the speaker's own imagination. "I can't see how an eye could evolve, so it didn't." The first half is a fact about the speaker. The second is a claim about eyes. - Promissory materialism is the same move from the other side of the table. "Science will explain consciousness one day, so there is nothing but the brain." Karl Popper named it in 1977: a promise wearing the clothes of an explanation. Therefore, an appeal to ignorance is not the honest sentence "we don't know." It is a conclusion drawn from that sentence, as though not knowing were a kind of knowing.

(●) Simple example: "Nobody has proved the old Harper house isn't haunted, so it must be." + The boy who says this has never been past the gate. His sister answers, "Nobody has proved it is, so it isn't." (1) What is claimed and what is offered. - The claim is that the house is haunted, and the support is that nobody has disproved it. His sister runs the same support the other way and gets the opposite conclusion out of it. (2) Why the support does no work. - The house is exactly as it was before either child spoke. Nobody has ever spent a night there with a thermometer, so the absence of a disproof is what you would expect either way. - Try the swap. Any unexamined claim does just as well in that slot: nobody has proved the Harpers didn't bury gold in the cellar either, and nobody thinks that settles the cellar. - What would bear on the question is somebody going in, knowing what a haunting would look like, and reporting back. (3) What the reply was really doing. - It was handing the work of proof to the doubter and calling the doubter's silence a verdict. Both children walked away with a conclusion, and neither of them had opened the door.

(●) A critic says: "There is no evidence for God, so God does not exist." + This is the sentence a Christian is most likely to hear from a thoughtful coworker. It deserves better than the mirror-image sentence Christians are tempted to throw back, because there is a real argument buried in it. (1) What is being argued. - The claim is that God does not exist. The support is that no evidence for him has been produced. At its strongest the critic has read the arguments and found each of them wanting, so "no evidence" means "nothing that survived inspection". - The nearest published form is Christopher Hitchens's rule in God Is Not Great (2007), usually called Hitchens's razor: whatever is asserted without evidence may be dismissed without evidence. It is a memorable line. It is also a rule about who has to do the arguing, which is a different thing from an argument that God is absent. (2) Where the fallacy sits. - The slide is from "no evidence for" to "evidence against", and nothing bridges it. Whether an empty search counts depends on whether the evidence would have turned up if God existed, and the sentence never says what the critic expected to find or where he looked. The empty fridge counted only because you knew what milk looks like and where it lives. - Try the mirror. "You can't prove God doesn't exist, so he does." Every critic knows how empty that is, and the emptiness is the same in both directions. - Honestly applied, the razor leaves the critic at "not shown", which is a long way from "false". What it settles is the burden of proof, the question of which side has to make its case before the other has to answer. Crossing from "not shown" to "false" takes an argument, and the razor does not supply one. (3) The sound version. - J. L. Schellenberg's Divine Hiddenness and Human Reason (1993) is what the critic should have said. A perfectly loving God would want every person capable of a relationship with him to be able to have one, and so would not leave anyone who is open to him unable even to believe he exists. Yet there are such people: open, and not believing. Schellenberg called this reasonable nonbelief, and later, more carefully, nonresistant nonbelief. So, he concludes, a perfectly loving God does not exist. - That argument runs on what we know rather than on what we do not. It says where the evidence should be, in the mind of every open person, and reports that it is not there. "There is no evidence for God" never says that much, and Schellenberg's version has to be answered on its merits. Christian philosophers have spent thirty years doing that, mostly by asking whether God might have reasons to leave room for a free response, and whether the nonbelief is as nonresistant as it looks. (4) How to answer it. - "What would you expect to see if God did exist that you don't see? Tell me that, and we have an argument worth having. Until then, 'no evidence' tells me what you haven't accepted, not what isn't there." See also: Natural Theology: The Kalam Argument Natural Theology: Cosmic Fine-Tuning

(●) A Christian says: "Science can't explain the origin of life, so God did it." + This is the gap argument in its plainest form. It has to be taken apart without flinching, because the critics who mock it learned the mockery from Christians. (1) What is being argued. - The claim is that God created the first life directly. The support is that chemistry has no account of how a living cell arose from non-living matter. - The strongest form should be granted in full. The origin of life is an open problem, the researchers working on it say so themselves, and this gap has not closed the way the gaps in astronomy did. (2) Where the fallacy sits. - The slide is from "no known natural explanation" to "therefore God", and it makes God's presence depend on chemistry's absence. - Christians saw the trouble with that long before any critic did. In 1894 the evangelist Henry Drummond mocked believers who comb through science looking for gaps to fill with God, asking whether God lived in gaps. Writing from Tegel prison in May 1944, Dietrich Bonhoeffer put it this way: "We are to find God in what we know, not in what we don't know." Coulson's line a decade later was that God is in the whole of nature, with no gaps, or not there at all. - Try the mirror. "Science can't explain consciousness yet, but it will, so there is nothing for God to do." That is Popper's promissory materialism, and a Christian who argues from gaps cannot object when the naturalist argues from promises. - Personal incredulity is the same move one size smaller. "I can't see how the eye could evolve" reports the limits of the speaker's imagination, which the eye did not consult. (3) The sound version. - The cure is to argue from what is known rather than from what is not, and Scripture itself argues that way: "For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made" (Romans 1:20). Paul points at what has been made, not at what nobody has explained. - Stephen Meyer's Signature in the Cell (2009) is the argument the Christian should have made, whatever one thinks of it. DNA carries functional information, a code that specifies working proteins, and in all our experience information of that kind comes from minds. - Meyer offers this as an inference to the best explanation, the detective's way of reasoning: of the causes known to produce this kind of effect, which one best accounts for the evidence in hand? That shape is right, because it starts from what the cell shows. His critics reply that "in all our experience" is quietly doing the old work of "we know no other way", so the gap argument is back in better clothes. (4) How to answer it, when a fellow Christian says it. - "If a chemist published a pathway next year, would your case be in trouble? Then don't rest it there. Argue from what the cell shows, not from what the chemists haven't found." See also: Natural Theology: Cosmic Fine-Tuning Natural Theology: The Kalam Argument

(●) A charge that misses: "Fine-tuning is just god of the gaps with equations. Physics hasn't explained the constants yet, so you put God there." + The charge sounds tidy, and sometimes it lands. It misses the argument itself, and seeing why draws the line between a gap argument and a sound one. (1) What the charge claims. - The fine-tuning argument observes that the constants of physics and the universe's initial conditions fall inside a narrow life-permitting range, and argues that a designer explains this far better than chance. The charge says this is really "physics cannot explain the constants, so God set them": a gap with a decimal point. (2) Why the charge misses. - A gap argument infers from ignorance of a mechanism. The fine-tuning argument infers from known values: it takes the measured constants and asks how surprising they are with a designer and without one. That is likelihood reasoning: an observation counts for whichever hypothesis makes it less surprising, the way a footprint in the flowerbed counts for the burglar over the wind. Robin Collins's chapter in The Blackwell Companion to Natural Theology (2009) is the standing statement. - A gap argument has no rivals, since it explains nothing. The fine-tuning argument has one, the multiverse (vast numbers of universes with different constants, so that a life-permitting one was bound to turn up somewhere), and it engages that rival on the same data, as an argument from evidence must. - Here is where somebody always reaches for the slogan: absence of evidence is not evidence of absence. As it stands, that is false. You would have seen an elephant in the room, and a drug trial that finds no effect has found something. - Walton names the two conditions: the search was thorough, and the evidence would have turned up if the claim were true. Copi's textbook agrees: where qualified investigators would have found the evidence, its absence is reason to think there was none. So the test to carry away is this. Has anyone looked where the evidence would be, and would they have found it? - The test cuts both ways. Schellenberg's hiddenness argument passes it, because he says where the evidence should be. A gap argument fails it, because it never says why a natural pathway would have been found by now. (3) What the charge would need to be true. - It would need to show that the argument rests on "physics cannot explain the constants" rather than on the constants themselves. A deeper law fixing the constants to life-permitting values would itself be a fine-tuned fact, and Collins says so. - The charge partly lands, and that should be granted. Some popular presentations really do say "physicists can't explain it, so God", and those are gap arguments whatever equations they wave. The argument is revisable too, since it rests on current physics, but so is every argument from evidence. (4) How to answer it. - "A gap argument says 'nobody knows, so God.' Fine-tuning says 'here is what we know, and how likely it is on each view.' You can argue the numbers or offer the multiverse; those are real replies. Calling it a gap argument isn't one." See also: Natural Theology: Cosmic Fine-Tuning