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“Appeal to ignorance -- the claim that whatever has not been proved false must be true, and vice versa (e.g.,There is no compelling evidence that UFOs are not visiting the Earth; therefore UFOs exist -- and there is intelligent life elsewhere in the Universe. Or: There may be seventy kazillion other worlds, but not one is known to have the moral advancement of the Earth, so we're still central to the Universe.) This impatience with ambiguity can be criticized in the phrase: absence of evidence is not evidence of absence.” ---Carl Sagan

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“Appeal to ignorance -- the claim that whatever has not been proved false must be true, and vice versa (e.g.,There is no compelling evidence that UFOs are not visiting the Earth; therefore UFOs exist -- and there is intelligent life elsewhere in the Universe. Or: There may be seventy kazillion other worlds, but not one is known to have the moral advancement of the Earth, so we're still central to the Universe.) This impatience with ambiguity can be criticized in the phrase: absence of evidence is not evidence of absence.” ---Carl Sagan

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"absence of evidence is not evidence of absence."

Are these logical fallacies:

All scientific theories must be falsifiable.

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Another type of reasoning is called "auto-epistemic" ("self-knowing") because it involves reasoning from premises about what one knows and what one would know if something were true. The form of such reasoning is:

If p were true, then I would know that p.
I don't know that p.
Therefore, p is false.

Similarly, when extensive investigation has been undertaken, it is often reasonable to infer that something is false based upon a lack of positive evidence for it. For instance, if a drug has been subjected to lengthy testing for harmful effects and none has been discovered, it is then reasonable to conclude that it is safe. Another example is:

~If there really were a large and unusual type of animal in Loch Ness, then we would have undeniable evidence of it by now.
~We don't have undeniable evidence of a large, unfamiliar animal in Loch Ness.
~Therefore, there is no such animal.

As with reasoning using the closed world assumption, auto-epistemic reasoning does not commit the fallacy of argument from ignorance. --- Gary N. Curtis

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Valiant Dancer,

Thanks for your response.

Do I need to argue that ‘auto-epistemic' reasoning is an exception to the logical fallacy argumentum ad ignorantiam?

Or perhaps some other name, perhaps I'm stuck on the word 'exception', if you could point me in the right direction. I'm still looking for a ‘simplistic' explanation.

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“Marvin, there are never any exceptions to a fallacy. Let me put this another way: There is no time, place, situation, or purpose in which it is permissible to use a logical fallacy!” ---Tim

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‘absence of evidence is not evidence of absence'

{View 1} Since you cannot disprove that there are flying saucers, you should accept as reliable the reports of those claiming to have seen such objects.

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Assuming this is an argument, we next differentiate between a deductive argument and inductive argument. The use of the word “empirical” leads to a pragmatic conclusion that this is an inductive argument. There are two different kinds of inductive arguments: Inductive Generalizations and Hypothetical Reasoning (a.k.a. Interpretive Arguments).

{View 2} Flying saucers do not exist, there is no empirical evidence.

This is an example of Hypothetical Reasoning. Its conclusion is "Flying saucers do not exist". It's a Descriptive Explanation. The argument has 1 premise; "There is no empirical evidence." is attempting to establish explanatory clarity by confirming the conclusion.

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{View 2} Flying saucers do not exist, there is no empirical evidence.

HASTY GENERALIZATION (SECUNDUM QUID)
Description: An argument in which a proposition is used as a premise without attention given to some obvious condition that would affect the proposition's application. This fallacy is also known as the "hasty generalization." It is a fallacy that takes evidence from several, possibly unrepresentative, cases to a general rule; generalizing from few to many. Note the relation to statistics: Much of statistics concerns whether or not a sample is representative of a larger population. The larger the sample size, the better the representativeness. Note also that the opposite of a hasty generalization is a sweeping generalization. ---Logical Fallacies

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Another type of reasoning is called "auto-epistemic" ("self-knowing") because it involves reasoning from premises about what one knows and what one would know if something were true. The form of such reasoning is:

If p were true, then I would know that p.
I don't know that p.
Therefore, p is false.

Similarly, when extensive investigation has been undertaken, it is often reasonable to infer that something is false based upon a lack of positive evidence for it. For instance, if a drug has been subjected to lengthy testing for harmful effects and none has been discovered, it is then reasonable to conclude that it is safe. Another example is:

~If there really were a large and unusual type of animal in Loch Ness, then we would have undeniable evidence of it by now.
~We don't have undeniable evidence of a large, unfamiliar animal in Loch Ness.
~Therefore, there is no such animal.

As with reasoning using the closed world assumption, auto-epistemic reasoning does not commit the fallacy of argument from ignorance. --- Gary N. Curtis

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Valiant Dancer,

Thanks for your response.

Do I need to argue that ‘auto-epistemic' reasoning is an exception to the logical fallacy argumentum ad ignorantiam?

Or perhaps some other name, perhaps I'm stuck on the word 'exception', if you could point me in the right direction. I'm still looking for a ‘simplistic' explanation.

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AFFIRMATION OF THE CONSEQUENT

Description: An argument from the truth of a hypothetical statement, and the truth of the consequent to the truth of the antecedent. In the syllogism below, P is the antecedent and Q is the consequent:

P implies Q
Q is true <-- Affirming the consequent
Therefore: P is true

1) Flying saucers do not exist. [because] There is no empirical evidence.
2) There is no empirical evidence.
3) Therefore: Flying saucers do not exist.

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The fallacy of ‘Affirming the Consequent' is at the heart of the scientific method.

Inference to the best explanation or the hypothetico-deductive method.

This method of argument is used greatly in science. It begins with a group of phenomena, which are to be explained. In seeking to explain these phenomena a series of hypotheses are invented from which the phenomena can be deduced.

1) If H, then P.____1) If it has rained, the streets will be wet.
2) P._____________2) The streets are wet.
3) Therefore: H.____3) Therefore it has rained.

From the considerations above it follows that inference to the best explanation or the hypothetico-deductive method can reach conclusions, which are at best probable {ie a street sweeper could cause the streets to be wet}

Evaluating Inferences to Best Explanation

What do we mean by "best explanation"? I.e. under what conditions can we be confident in the truth of the second premise and thus be confident that the explanation is probably true?

Firstly, how do we evaluate them for strength?

1. They should actually explain the event in question (not stand in need of explanation themselves).
2. They should be powerful (i.e. widely applicable).
3. The simpler the better.
4. They should be conservative with respect to prior beliefs, about the natural order of things.
5. They should be testable, with some way of acquiring evidence that would tend to confirm or disconfirm the hypothesis.

Deduction (or to give it its proper name, deductive logic) is a way of making authoritative statements (proofs) about what is not known by a thorough analysis of what is known. The ability to make deductive statements is a very powerful tool since it is the basis for drawing logical conclusions about specific events from general events.

A theory, in this interpretation, consists of confirmed hypotheses, since any large-scale piece of social research it is highly unlikely that a researcher would be testing a single hypothesis. Once this stage has been reached it should be possible to make predictions about behavior based on the theory that has been developed.

{View 2} Flying saucers do not exist, there is no empirical evidence.

Is explanatory, powerful, simple, and conservative to any prior beliefs. It is a strong deductive theory that is readily falsifiable {ie produce a piece of a flying saucer, the bigger --- the better} It is an inference to the best explanation of the phenomenon of reports of “Flying Saucers”. {nomological-deductive versus historical-narrative explanations}

This argument analysis may be the most accurate? But not the most ‘simplistic'