Cum Hoc Ergo Propter Hoc. A chart that, according to Bobby Henderson, correlates the number of pirates with global temperature.
The two variables are correlated, but one does not imply the other The counter assumption, that correlation proves causation, is considered a questionable cause logical fallacy in that two events occurring together are taken to have a cause-and-effect relationship. This fallacy is also known as cum hoc ergo propter hoc, Latin for "with this, therefore because of this", and "false cause". A similar fallacy, that an event that follows another was necessarily a consequence of the first event, is sometimes described as post hoc ergo propter hoc (Latin for "after this, therefore because of this"). Post Hoc Ergo Propter Hoc. Post hoc ergo propter hoc (Latin: "after this, therefore because of this") is a logical fallacy (of the questionable cause variety) that states "Since event Y followed event X, event Y must have been caused by event X.
" It is often shortened to simply post hoc. It is subtly different from the fallacy cum hoc ergo propter hoc (correlation does not imply causation), in which two things or events occur simultaneously or the chronological ordering is insignificant or unknown. Post hoc is a particularly tempting error because temporal sequence appears to be integral to causality. Law of Thought. The laws of thought are fundamental axiomatic rules upon which rational discourse itself is often considered to be based.
The formulation and clarification of such rules have a long tradition in the history of philosophy and logic. Generally they are taken as laws that guide and underlie everyone's thinking, thoughts, expressions, discussions, etc. According to the 1999 Cambridge Dictionary of Philosophy, laws of thought are laws by which or in accordance with which valid thought proceeds, or that justify valid inference, or to which all valid deduction is reducible.
Laws of thought are rules that apply without exception to any subject matter of thought, etc.; sometimes they are said to be the object of logic. Law of Excluded Middle. In logic, the law of excluded middle (or the principle of excluded middle) is the third of the three classic laws of thought.
It states that for any proposition, either that proposition is true, or its negation is true. The law is also known as the law (or principle) of the excluded third, in Latin principium tertii exclusi. Law of Noncontradiction. This article uses forms of logical notation.
For a concise description of the symbols used in this notation, see List of logic symbols. In classical logic, the law of non-contradiction (LNC) (or the law of contradiction (PM) or the principle of non-contradiction (PNC), or the principle of contradiction) is the second of the three classic laws of thought. It states that contradictory statements cannot both be true in the same sense at the same time, e.g. the two propositions "A is B" and "A is not B" are mutually exclusive. Law of Identity. This article uses forms of logical notation.
For a concise description of the symbols used in this notation, see List of logic symbols. In logical discourse, violations of the Law of Identity (LOI) result in the informal logical fallacy known as equivocation. That is to say, we cannot use the same term in the same discourse while having it signify different senses or meanings – even though the different meanings are conventionally prescribed to that term. In everyday language, violations of the LOI introduce ambiguity into the discourse, making it difficult to form an interpretation at the desired level of specificity. History Rhetological Fallacies. Buy a printable PDF in English and in French.
Read the French version – Thanks to Gilles Peyroux. See a text-only version.