Argument from ignorance

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Argument from ignorance (from Latin : argumentum ad ignorantiam), also known as appeal to ignorance (in which ignorance represents "a lack of contrary evidence"), is a fallacy in informal logic. The fallacy is committed when one asserts that a proposition is true because it has not yet been proven false or a proposition is false because it has not yet been proven true. If a proposition has not yet been proven true, one is not entitled to conclude, solely on that basis, that it is false, and if a proposition has not yet been proven false, one is not entitled to conclude, solely on that basis, that it is true. [1] [2] Another way of expressing this is that a proposition is true only if proven true, and a proposition is false only if proven false. If no proof is offered (in either direction), then the proposition can be called unproven, undecided, inconclusive, an open problem or a conjecture. In debates, appealing to ignorance is sometimes an attempt to shift the burden of proof. The term was likely coined by philosopher John Locke in the late 17th century. [3] [4]

Contents

Examples

"Simply because you do not have evidence that something exists does not mean that you have evidence that it doesn't exist." [6] [lower-alpha 1]

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. [8]

Contraposition and transposition

Contraposition is a logically valid rule of inference that allows the creation of a new proposition from the negation and reordering of an existing one. The method applies to any proposition of the type "If A then B" and says that negating all the variables and switching them back to front leads to a new proposition i.e. "If Not-B then Not-A" that is just as true as the original one and that the first implies the second and the second implies the first.

Transposition is exactly the same thing as Contraposition, described in a different language.

Null result

Null result is a term often used in science to indicate evidence of absence . A search for water on the ground may yield a null result (the ground is dry); therefore, it probably did not rain.

Argument from self-knowing

Arguments from self-knowing take the form:

  1. If P were true then I would know it; in fact I do not know it; therefore P cannot be true.
  2. If Q were false then I would know it; in fact I do not know it; therefore Q cannot be false.

In practice these arguments are often unsound and rely on the truth of the supporting premise. For example, the claim that If I had just sat on a wild porcupine then I would know it is probably not fallacious and depends entirely on the truth of the first premise (the ability to know it).

See also

Notes

  1. ↑ Though the authors here caution that this may not be an entirely appropriate use of the argument as the onus of providing proof for a substantive statement, like "there are WMDs in Iraq", lies with the party making the claim, not with those opposing it.

Related Research Articles

In propositional logic, modus tollens (MT), also known as modus tollendo tollens and denying the consequent, is a deductive argument form and a rule of inference. Modus tollens is a mixed hypothetical syllogism that takes the form of "If P, then Q. Not Q. Therefore, not P." It is an application of the general truth that if a statement is true, then so is its contrapositive. The form shows that inference from P implies Q to the negation of Q implies the negation of P is a valid argument.

In classical rhetoric and logic, begging the question or assuming the conclusion is an informal fallacy that occurs when an argument's premises assume the truth of the conclusion. Historically, begging the question refers to a fault in a dialectical argument in which the speaker assumes some premise that has not been demonstrated to be true. In modern usage, it has come to refer to an argument in which the premises assume the conclusion without supporting it. This makes it an example of circular reasoning.

<span class="mw-page-title-main">Fallacy</span> Argument that uses faulty reasoning

A fallacy is the use of invalid or otherwise faulty reasoning in the construction of an argument that may appear to be well-reasoned if unnoticed. The term was introduced in the Western intellectual tradition by the Aristotelian De Sophisticis Elenchis.

Deductive reasoning is the process of drawing valid inferences. An inference is valid if its conclusion follows logically from its premises, meaning that it is impossible for the premises to be true and the conclusion to be false. For example, the inference from the premises "all men are mortal" and "Socrates is a man" to the conclusion "Socrates is mortal" is deductively valid. An argument is sound if it is valid and all its premises are true. One approach defines deduction in terms of the intentions of the author: they have to intend for the premises to offer deductive support to the conclusion. With the help of this modification, it is possible to distinguish valid from invalid deductive reasoning: it is invalid if the author's belief about the deductive support is false, but even invalid deductive reasoning is a form of deductive reasoning.

In logic and mathematics, the converse of a categorical or implicational statement is the result of reversing its two constituent statements. For the implication P → Q, the converse is Q → P. For the categorical proposition All S are P, the converse is All P are S. Either way, the truth of the converse is generally independent from that of the original statement.

Argument from fallacy is the formal fallacy of analyzing an argument and inferring that, since it contains a fallacy, its conclusion must be false. It is also called argument to logic, the fallacy fallacy, the fallacist's fallacy, and the bad reasons fallacy.

<span class="mw-page-title-main">Affirming a disjunct</span> Formal fallacy

The formal fallacy of affirming a disjunct also known as the fallacy of the alternative disjunct or a false exclusionary disjunct occurs when a deductive argument takes the following logical form:

<span class="mw-page-title-main">Informal fallacy</span> Form of incorrect argument in natural language

Informal fallacies are a type of incorrect argument in natural language. The source of the error is not just due to the form of the argument, as is the case for formal fallacies, but can also be due to their content and context. Fallacies, despite being incorrect, usually appear to be correct and thereby can seduce people into accepting and using them. These misleading appearances are often connected to various aspects of natural language, such as ambiguous or vague expressions, or the assumption of implicit premises instead of making them explicit.

In philosophical logic, the masked-man fallacy is committed when one makes an illicit use of Leibniz's law in an argument. Leibniz's law states that if A and B are the same object, then A and B are indiscernible. By modus tollens, this means that if one object has a certain property, while another object does not have the same property, the two objects cannot be identical. The fallacy is "epistemic" because it posits an immediate identity between a subject's knowledge of an object with the object itself, failing to recognize that Leibniz's Law is not capable of accounting for intensional contexts.

In logic and philosophy, a formal fallacy is a pattern of reasoning rendered invalid by a flaw in its logical structure that can neatly be expressed in a standard logic system, for example propositional logic. It is defined as a deductive argument that is invalid. The argument itself could have true premises, but still have a false conclusion. Thus, a formal fallacy is a fallacy in which deduction goes wrong, and is no longer a logical process. This may not affect the truth of the conclusion, since validity and truth are separate in formal logic.

Epistemic modal logic is a subfield of modal logic that is concerned with reasoning about knowledge. While epistemology has a long philosophical tradition dating back to Ancient Greece, epistemic logic is a much more recent development with applications in many fields, including philosophy, theoretical computer science, artificial intelligence, economics, and linguistics. While philosophers since Aristotle have discussed modal logic, and Medieval philosophers such as Avicenna, Ockham, and Duns Scotus developed many of their observations, it was C. I. Lewis who created the first symbolic and systematic approach to the topic, in 1912. It continued to mature as a field, reaching its modern form in 1963 with the work of Kripke.

In logic and mathematics, contraposition, or transposition, refers to the inference of going from a conditional statement into its logically equivalent contrapositive, and an associated proof method known as § Proof by contrapositive. The contrapositive of a statement has its antecedent and consequent inverted and flipped.

Evidence of absence is evidence of any kind that suggests something is missing or that it does not exist. What counts as evidence of absence has been a subject of debate between scientists and philosophers. It is often distinguished from absence of evidence.

In logic, specifically in deductive reasoning, an argument is valid if and only if it takes a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false. It is not required for a valid argument to have premises that are actually true, but to have premises that, if they were true, would guarantee the truth of the argument's conclusion. Valid arguments must be clearly expressed by means of sentences called well-formed formulas.

<i>Reductio ad absurdum</i> Argument that leads to a logical absurdity

In logic, reductio ad absurdum, also known as argumentum ad absurdum or apagogical arguments, is the form of argument that attempts to establish a claim by showing that the opposite scenario would lead to absurdity or contradiction.

The burden of proof is the obligation on a party in a dispute to provide sufficient warrant for its position.

In argumentation theory, an argumentum ad populum is a fallacious argument which is based on claiming a truth or affirming something is good or correct because many people think so.

An argument from authority is a form of argument in which the opinion of an authority figure is used as evidence to support an argument.

An argument from anecdote is an informal logical fallacy, when an anecdote is used to draw an improper logical conclusion. The fallacy can take many forms, such as cherry picking, hasty generalization, proof by assertion, and so on.

References

  1. ↑ Copi, Irving M (2016). Introduction to logic (14th ed.). Routledge Publication. p. 146. ISBN   9780205820375.
  2. ↑ Hurley, Patrick J (2012). A Concise Introduction to Logic (11th ed.). Boston, Mass.: Cengage Learning. p. 140. ISBN   9780840034175.
  3. ↑ Hansen, Hans V.; Pinto, Robert C., eds. (1995). Fallacies: Classical and Contemporary Readings. University Park, Pa.: Pennsylvania State University Press. ISBN   978-0271014166. OCLC   30624864.
  4. ↑ Locke, John (1690). "Book IV, Chapter XVII: Of Reason". An Essay Concerning Human Understanding. Retrieved 12 March 2015.
  5. ↑ Bennett, Bo. "Argument from Ignorance". www.LogicallyFallacious.com. Retrieved 23 November 2016.
  6. ↑ Brown, Deborah; Key, Brian (22 April 2019). "You look but do not find: why the absence of evidence can be a useful thing". The Conversation. Archived from the original on 15 June 2021. Retrieved 20 June 2022.
  7. ↑ Daily Kos. "Logical Fallacies Bootcamp: Appeal to Ignorance".
  8. ↑ Sagan, Carl. "Chapter 12: The Fine Art of Baloney Detection". The Demon-Haunted World.

Further reading

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