Argumentum ad ignorantiam
The argumentum ad ignorantiam (also known as the argument from ignorance) is a logical fallacy wherein the speaker claims that a proposition is true because it has not been shown to be false, or vice versa. The argument is a form of non sequitur and a false dichotomy.
Someone using the argument from ignorance will generally claim that either:
- They don't know how an argument could be false, therefore it must be true.
- They don't know how an argument could be true, therefore it must be false.
- Since scientists cannot prove that global warming will occur, it probably won't. 
- Failure to foresee that diversity in life would eventually be explained by Charles Darwin:
"There will never be an Isaac Newton for a blade of grass."
- "This a homage is rendered to the sacred seal [of obscurity], which the Almighty has set upon each of his works. "
- "What powered inflation of the universe? Why are humans spiritual? Where did consciousness come from? How do you explain what some have called our 6th sense? How did the Earth overcome what MIT and Stanford physicists call statistically miraculous odds to have habitable conditions? Why does humanity cherish humility and honesty over pride and deceit? Why do almost all feel compelled to do what is right by helping neighbors? Why is there a norm of reciprocity? What is our greater purpose? Why is there evil in the world?" 
Use in apologetics
The argumentum ad ignorantiam is commonly used as a proof of the existence of God. It is the fallacy that is perhaps the most common in religious apologetics.
God of the gaps
- Main Article: God of the gaps
The most common form in apologetics is the "God of the gaps" argument which argues that since some phenomenon is unexplained, it must be due to God. It is also a form of non sequitur, since the hand of God is posited without proof and often with complete disregard to other possible explanations.
Argument from personal incredulity
Argument from personal incredulity is a statement like "I can't see how that is possible, therefore it is impossible". It is a form of argument from ignorance.
It contains an unstated premise: "if something cannot be understood to be possible, it is impossible". This overlooks the possibility that the speaker lacks knowledge or has a failure of imagination.
Apologetic arguments that commit this fallacy include:
- Argument from design
- Irreducible complexity
- Intelligent design
- Various theodicies for the problem of evil
- Argument from abiogenesis
- Natural-law argument
- Fine-tuning argument
- Argument from desire
- Transcendental argument
- Information theory argument
- Argument from the meaning of life
- Presuppositional apologetics
- Scientific foreknowledge in sacred texts
- Argument from suffering
- Argument from miracle testimony
- Argument from prophecy
- Argument from the origin of the idea of God
- Argument from conscience
- Argument from providence
- Religion explains the human condition
- Argument from comprehensibility
- The first cause implies God exists
- Argument from personal coincidences
- Argument from altruism
- Argument from free will
- Argument from mathematical realism
- Argument from religious teachings
- If God didn't create everything, who did?
- Argument to ignorance at The Skeptic's Dictionary
- Example of argument from incredulity, Atheist Experience, 2016-7-3