One of the first things to discover when adopting a skeptical viewpoint is how vastly ignorant we all are of much of what there is to know. But ignorance isn’t bliss, it’s oblivion. And it’s evil twin, the illusion of knowledge, is downright dangerous.
This post deals with a common mistake in thinking that preys on ignorance, trying to make it seem like knowledge, the Argument from Ignorance, also the Appeal to Ignorance or ad ignorantiam.
It attempts to make a definite statement on a claim by using what is not known rather than what is. It often takes the general form of:
I don’t know X, so I know Y.
Or put differently it goes something like this:
No one has proven X false (or true), so X must be true (or false).
I can’t explain X, so I can explain X.
A few examples follow:
No one has proven that Godzilla doesn’t exist, so Godzilla is real.
No one has proven that secondhand smoke causes cancer, so it must be harmless.
I’ve never seen any real, absolute, rock-solid proof that the Apollo astronauts landed on the Moon, so the Apollo missions were a hoax.
There’s no fallacy committed when there’s knowledge of missing evidence that should logically be found, and it’s known what the expected evidence ought to be. Absence of evidence in the right context is indeed evidence of absence when its lack is glaringly obvious, even if it’s not certain proof of absence!
There’s no fallacy committed in and of itself when acting upon incomplete data for precautionary purposes, such as the threat of terrorists, who can be expected to operate in secret until they strike, if and when they do, or acting upon the threat of global warming in the absence of complete and absolute certainty.
The following is a valid argument:
All of the scheduled openings of this library are listed. I don’t see a listing of it opening at this hour of the day. So it must be that the library will be closed until two hours from now.
This, however, is not:
I see a strange light in the sky. I can’t think of an explanation for it off the top of my head. It must be an alien spaceship.
There are gaps in the fossil record. I do not know of a plausible explanation as to why there are such gaps. So it must be that a Intelligent Designer has created or interceded in the creation of life.
A variation of this is Confusing the Unexplained with the Unexplainable, which is fallacious because it assumes implicitly that the current state of knowledge represents the ultimate limits of the knowable, which is just wrong on so many levels.
There’s a possibly apocryphal anecdote floating about of a patent clerk in the late 19th or early 20th century who quit his job, because he thought that everything important had already been invented.
There’s also the silly claim, still circulated, that it’s impossible for bumblebees to fly because science can’t explain it, therefore it’s magic. Well, science has explained it, and it deals with the mechanics of a bumblebee’s wings and the physics of fluid dynamics.
This is understandable, even from perfectly normal, intelligent, sane, and sincere people. It’s reasoning from psychologically available information rather than an examination of more complex and difficult data that may not come as quickly or easily to mind.
It just so happens that supernatural or paranormal explanations are among the easiest to conceive of on the spur of the moment. They are more immediately available, and we are more prone to them through the biases and mental shortcuts we take in our default thinking under whatever narrative influences our brains at any given moment, to paraphrase Dr. Steven Novella.
In informal argumentation the fallacious use of the argument from ignorance is not a violation of logical form as much as an attempt to subvert efforts toward getting at sound explanations for our claims.