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Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the study of deductively valid inferences or logical truths. It examines how conclusions follow from premises based on the structure of arguments alone, independent of their topic and content.
- Overview
- Nature and varieties of logic
philosophy of logic, the study, from a philosophical perspective, of the nature and types of logic, including problems in the field and the relation of logic to mathematics and other disciplines.
The term logic comes from the Greek word logos. The variety of senses that logos possesses may suggest the difficulties to be encountered in characterizing the nature and scope of logic. Among the partial translations of logos, there are “sentence,” “discourse,” “reason,” “rule,” “ratio,” “account” (especially the account of the meaning of an expression), “rational principle,” and “definition.” Not unlike this proliferation of meanings, the subject matter of logic has been said to be the “laws of thought,” “the rules of right reasoning,” “the principles of valid argumentation,” “the use of certain words labelled ‘logical constants’,” “truths (true propositions) based solely on the meanings of the terms they contain,” and so on.
It is relatively easy to discern some order in the above embarrassment of explanations. Some of the characterizations are in fact closely related to each other. When logic is said, for instance, to be the study of the laws of thought, these laws cannot be the empirical (or observable) regularities of actual human thinking as studied in psychology; they must be laws of correct reasoning, which are independent of the psychological idiosyncrasies of the thinker. Moreover, there is a parallelism between correct thinking and valid argumentation: valid argumentation may be thought of as an expression of correct thinking, and the latter as an internalization of the former. In the sense of this parallelism, laws of correct thought will match those of correct argumentation. The characteristic mark of the latter is, in turn, that they do not depend on any particular matters of fact. Whenever an argument that takes a reasoner from p to q is valid, it must hold independently of what he happens to know or believe about the subject matter of p and q. The only other source of the certainty of the connection between p and q, however, is presumably constituted by the meanings of the terms that the propositions p and q contain. These very same meanings will then also make the sentence “If p, then q” true irrespective of all contingent matters of fact. More generally, one can validly argue from p to q if and only if the implication “If p, then q” is logically true—i.e., true in virtue of the meanings of words occurring in p and q, independently of any matter of fact.
Logic may thus be characterized as the study of truths based completely on the meanings of the terms they contain.
In order to accommodate certain traditional ideas within the scope of this formulation, the meanings in question may have to be understood as embodying insights into the essences of the entities denoted by the terms, not merely codifications of customary linguistic usage.
The following proposition (from Aristotle), for instance, is a simple truth of logic: “If sight is perception, the objects of sight are objects of perception.” Its truth can be grasped without holding any opinions as to what, in fact, the relationship of sight to perception is. What is needed is merely an understanding of what is meant by such terms as “if–then,” “is,” and “are,” and an understanding that “object of” expresses some sort of relation.
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Sep 30, 2024 · Logic, the study of correct reasoning, especially as it involves the drawing of inferences. This article discusses the basic elements and problems of contemporary logic and provides an overview of its different fields. For treatment of the historical development of logic, see logic, history of. For.
In logic, we study the rules and techniques that allow us to distinguish good, correct reasoning from bad, incorrect reasoning. Since there are a variety of different types of reasoning and methods with which to evaluate each of these types, plus various diverging views on what constitutes correct reasoning, there are many approaches to the logical enterprise.
Logic. Logic (from the Greek "logos", which has a variety of meanings including word, thought, idea, argument, account, reason or principle) is the study of reasoning, or the study of the principles and criteria of valid inference and demonstration. It attempts to distinguish good reasoning from bad reasoning.
Although Logic is a single field of study, there is more than one logic in this field. In the three main units of this book, we look at three different types of logic, each more sophisticated than the one before. Propositional Logic is the logic of propositions. Symbols in the language represent "conditions" in the world, and complex sentences ...
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Philosophy of logic is the area of philosophy that studies the scope and nature of logic. It investigates the philosophical problems raised by logic, such as the presuppositions often implicitly at work in theories of logic and in their application. This involves questions about how logic is to be defined and how different logical systems are ...
