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Mental
Logic and Reasoning
Logic is the study of correct reasoning, and reason is the ability to draw valid conclusions from information in search of the truth.
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The idea
Logic and reasoning are about thinking well. Reason is the ability to use logic on purpose. People reason when they draw valid conclusions from new or existing information, with the aim of finding the truth. Logic is the study of correct reasoning. It looks at arguments, which are sets of premises that lead to a conclusion. An argument is correct if its premises support its conclusion.
Reasoning comes in several forms. In a deductive argument, if the premises are true, the conclusion must also be true. Inductive reasoning makes generalizations from many observations, such as deciding that all ravens are black after seeing many black ravens. Abductive reasoning looks for the best explanation, as when a doctor decides which disease best explains a patient's symptoms. Arguments that fall short of the standards of correct reasoning often contain fallacies.
Logic is also divided into formal and informal logic. Formal logic studies how conclusions follow from the structure of arguments alone. It often uses special symbols. Informal logic studies arguments in everyday language and is linked to critical thinking. Logic plays a central role in many fields, including philosophy, mathematics, computer science and linguistics. Psychologists and cognitive scientists also study how people really reason. Real people do not always reason the way logic says they should.
Check yourself
Question 1 of 2
What kind of reasoning infers the best explanation, as when a doctor matches symptoms to a disease?
Composition
what it's made of
- Arguments — A set of premises that leads to a conclusion.
- Deductive reasoning — Reasoning in which true premises guarantee a true conclusion.
- Inductive reasoning — Generalizing from many individual observations.
- Abductive reasoning — Inferring the best explanation for what is observed.
- Formal and informal logic — Formal logic studies argument structure; informal logic studies everyday arguments and critical thinking.
- Fallacies — Arguments that fall short of the standards of correct reasoning.
Connection
how it relates
Under Mental
Change
how and why it evolves
- Past
- Logic has been studied since ancient times, and early traditions include Aristotelian logic, Stoic logic, Nyaya and Mohism. In the West, Aristotelian logic was the main system until it was replaced by modern formal logic, which grew from the work of late 19th-century mathematicians such as Gottlob Frege.
- Now
- Logic now includes a great many systems, which scholars often sort into classical logic, extended logics and deviant logics.
- Next
- The field of automated reasoning, which studies how reasoning can be modeled by computers, will likely keep growing as people ask machines to explain their answers.