Logical constant
In logic, a logical constant of a language is a symbol that has the same semantic value under every interpretation of . Two important types of logical constants are logical connectives and quantifiers. The equality predicate (usually written '=') is also treated as a logical constant in many systems of logic. One of the fundamental questions in the philosophy of logic is "What is a logical constant?"; that is, what special feature of certain constants makes them logical in nature?[1]
Some symbols that are commonly treated as logical constants are:
Symbol | Meaning in English |
---|---|
T | "true" |
F | "false" |
¬ | "not" |
∧ | "and" |
∨ | "or" |
→ | "implies", "if...then" |
∀ | "for all" |
∃ | "there exists", "for some" |
= | "equals" |
"necessarily" | |
"possibly" |
Many of these logical constants are sometimes denoted by alternate symbols (e.g., the use of the symbol "&" rather than "∧" to denote the logical and).
See also
References
- ↑ Carnap
External links
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