From Academic Kids

The term fallacy denotes any mistaken statement used in an argument. In logic, it specifically means an argument that violates the rules of formal demonstration. Beginning with Aristotle, fallacies have generally been placed in one of three categories: a material fallacy (misstatement of facts), a verbal fallacy (improper use of words), or a logical fallacy (also called a formal fallacy—a mistake in the process of inference). The latter two fallacies are called fallacies in dictione (L., in delivery) or in voce (L., in expression), as opposed to material fallacies in re (L. in fact/cause/property) or extra dictionem (outside of/beside delivery).


Aristotelian fallacies

Material fallacies


  • Begging the question (also called Petitio Principii or Circulus in probando--arguing in a circle) consists in demonstrating a conclusion by means of premises which pre-suppose that conclusion. Jeremy Bentham points out that this fallacy may lurk in a single word, especially in an epithet, e.g. if a measure were condemned simply on the ground that it is alleged to be " un-English "
  • Fallacy of the Consequent, really a species of Irrelevant Conclusion, wherein a conclusion, is drawn from premises which do not really support it
  • Fallacy of False Cause, or Non Sequitur (L., it does not follow), wherein one thing is in-correctly assumed as the cause of another, as when the ancients attributed a public calamity to a meteorological phenomenon;

Verbal fallacies


  • Amphibology is the result of ambiguity of grammatical structure, e.g. of the position of the adverb " only " in careless writers (" Be only said that," in which sentence, as experience shows, the adverb has been intended to qualify any one of the other three words).
  • Fallacy of Composition is a species of Amphibology, which results from the confused use of collective terms. e.g. "The angles of a triangle are less than two right angles" might refer to the angles separately or added together.
  • Division, the converse, of the preceding, which consists in employing the middle term distributively in the minor and collectively in the major premise.

Aristotelian logical fallacies

The standard logical fallacies are:

Other systems of classification


Examples of fallacious arguments




Example 1: Material Fallacy

James argues:

  1. Application of the death penalty is killing a human being.
  2. Killing a human being is wrong.
  3. Therefore, application of the death penalty is wrong.

This argument claims to prove the death penalty is wrong. This particular argument has the form of a categorical syllogism. Any argument must have premises as well as a conclusion. In this case we need to ask what the premises are, that is the set of assumptions the proposer of the argument can expect the interlocutor to grant. The first assumption is almost true by definition: the death penalty is the judicially ordered execution of a prisoner as a punishment for a serious crime. The second assumption is less clear as to its meaning. Since the assertion has no quantifiers of any kind, it could mean any one of the following:

  • Every act of killing a human being is wrong.
  • Most acts of killing a human being are wrong.
  • All acts of killing a human being are wrong, except those that are carried out for some legitimate purpose such as deterring serious crime.
  • Some acts of killing a human being are wrong.

In any of the last three interpretations, the above syllogism would then fail to have validated its second premise. James may try to assume that his interlocutor believes every act of killing is wrong; if the interlocutor grants this then the argument is valid. In this case, the interlocutor is essentially conceding the point to James. However, the interlocutor is more likely to believe some acts of killing are not wrong, for instance those carried out in self defense or in legitimate warfare; and in this case James is not much better off than he was before he formulated the argument, since he now has to prove the assertion that the death penalty is not a legimate form of killing, which is a disguised form of the original thesis. From the point of view the interlocutor, James commits the logical fallacy of begging the question.

Example 2: Verbal Fallacy

Barbara argues:

  1. Andre is a good tennis player.


Example 3: Verbal Fallacy

A humorous variant of the fallacy of ambiguity is as follows. Ramesh argues:

  1. Nothing is better than eternal happiness.
  2. Eating a hamburger is better than nothing.


A potato is better than eternal happiness.

In fact it is semantically equivalent to the following universal quantification:

Everything fails to be better than eternal happiness.


Eating a hamburger fails to be better than eternal happiness.


Eating a hamburger is better than eating nothing at all.

Thus this is a fallacy of composition.

Example 4: Logical Fallacy


  1. Some acts of killing human beings are legal in this state.
  2. Some acts of killing human beings are illegal in this state.
  3. Therefore some acts of killing human beings are both legal and illegal in this state.

This is fallacious. Indeed, there is no logical principle which states

  1. For some x, P(x).
  2. For some y, Q(y).
  3. Then for some z, P(z) and Q(z).


Fallacies in the media and politics


The military uniform is a symbol of national strength and honor.


In the opposite direction is the fallacy of argument from authority. A classic example is the Ipse dixit—"He himself said it" argument—used throughout the Middle Ages in reference to Aristotle. A modern instance is "celebrity spokespersons" in advertisements: a product is good and you should buy/use/support it because your favorite celebrity endorses it.


By definition, arguments with logical fallacies are invalid, but they can often be (re)written in such a way that they fit a valid argument form. The challenge to the interlocutor is, of course, to discover the false premise, that is the premise which makes the argument unsound.

See also

Logical fallacy


Academic Kids Menu

  • Art and Cultures
  • Space and Astronomy



  • Clip Art (http://classroomclipart.com)
Personal tools