# Portal:Logic

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## Logic

Logic (from the Ancient Greek: λογική, translit. logikḗ), originally meaning "the word" or "what is spoken", but coming to mean "thought" or "reason", is a subject concerned with the most general laws of truth, and is now generally held to consist of the systematic study of the form of valid inference. A valid inference is one where there is a specific relation of logical support between the assumptions of the inference and its conclusion. (In ordinary discourse, inferences may be signified by words like therefore, hence, ergo, and so on.)

There is no universal agreement as to the exact scope and subject matter of logic (see § Rival conceptions, below), but it has traditionally included the classification of arguments, the systematic exposition of the 'logical form' common to all valid arguments, the study of inference, including fallacies, and the study of semantics, including paradoxes. Historically, logic has been studied in philosophy (since ancient times) and mathematics (since the mid-19th century), and recently logic has been studied in computer science, linguistics, psychology, and other fields.

## Selected article

In the formal languages used in mathematical logic and computer science, a well-formed formula or simply formula[2] (often abbreviated wff, pronounced "wiff" or "wuff") is an idea, abstraction or concept which is expressed using the symbols and formation rules (also called the formal grammar) of a particular formal language. To say that a string of symbols ${\displaystyle \ S}$ is a wff with respect to a given formal grammar ${\displaystyle \ G}$ is equivalent to saying that ${\displaystyle \ S}$ belongs to the language generated by ${\displaystyle \ G}$. A formal language can be identified with the set of its wffs.

## Selected biography

Aristotle (Greek: Ἀριστοτέλης, Aristotélēs) (384 BC – 322 BC) was a Greek philosopher, a student of Plato and teacher of Alexander the Great. He wrote on many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, politics, government, ethics, biology and zoology.

Together with Plato and Socrates (Plato's teacher), Aristotle is one of the most important founding figures in Western philosophy. He was the first to create a comprehensive system of Western philosophy, encompassing morality and aesthetics, logic and science, politics and metaphysics. Aristotle's views on the physical sciences profoundly shaped medieval scholarship, and their influence extended well into the Renaissance, although they were ultimately replaced by Newtonian Physics. In the biological sciences, some of his observations were confirmed to be accurate only in the nineteenth century. His works contain the earliest known formal study of logic, which was incorporated in the late nineteenth century into modern formal logic. In metaphysics, Aristotelianism had a profound influence on philosophical and theological thinking in the Islamic and Jewish traditions in the Middle Ages, and it continues to influence Christian theology, especially Eastern Orthodox theology, and the scholastic tradition of the Roman Catholic Church. All aspects of Aristotle's philosophy continue to be the object of active academic study today.

## Things to do

 Here are some tasks awaiting attention: Article requests : Anonymous authority  • Anti-Procreation Movement  • Appeal to classical allusions  • Archimedean Fulcrum  • Asserting an alternative  • Bad reasons fallacy  • Cartesian logic  • Common thread reasoning  • Conjunctive forks  • Converting a conditional  • Doctrine of Unexpected Consequences  • Dream logic  • Equivocity  • Fallacy of assuming a common cause  • Fallacy of biased generalization  • Conflicting conditions  • Failure to elucidate  • Too broad  • Too narrow  • Fallacies of distraction  • Fallacies of explanation  • Limited depth  • Limited scope  • Non-support  • Subverted support  • Untestability  • Fallacy of personal preference assumptions  • Fallacy of quantificational logic  • Fallacy of reverse causation  • Fallacy of the alternative syllogism  • Fallacy of the disjunctive syllogism  • Fallacy of the propositional logic  • Free time (fallacy)  • Futurist extrapolation  • Heads in the sand critique  • Ignoring common cause  • Illicit process  • Improper disjunctive syllogism  • Improper transposition  • Inferring from a metaphor  • Intuitionistic modal logic  • Jactication  • Kicking the problem upstairs  • Lennon/McCartney fallacy  • Liminocentricity  • List of valid argument forms Done  • List of invalid argument forms  • Logical notation  • Meinongian arguments  • Mereological arguments  • Negating antecedent and consequent  • Neutrality Schmeutrality  • One-sidedness  • Open Block Logic  • Oppositional logic  • Perfectly rigorous  • Physiological Egoism  • Plurivocity  • Postmodern mathematics  • Prejudicial language  • Pseudorefutation  • Quote-name  • Repetition (fallacy)  • Science fiction moralizing  • Significant difference reasoning  • Some are/some are not  • Sublime experience  • Superalternation  • Swiftian logic  • Tendentious appeal to possibilities  • truth-apt  • Truthmapping  • Unwarranted contrast  • Upwards inherited  • Volitive  • Weaseler  • John Arrington Woodward Other : Add links to this portal by placing {{Portal|Logic}} in the See also sections of relevant articles

## References

1. ^ Godel, Escher, Bach: An Eternal Golden Braid, Douglas Hofstadter
2. ^ Because non-well-formed formulas are rarely considered, some authors ignore them altogether. For these authors, "formula" and "well-formed formula" are synonyms. Other authors use the term "formula" for any string of symbols in the language; certain of these strings are then singled out as the well-formed formulas.

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