Conversion, Obversion and Contraposition Flashcards
What is an inference in logic?
An inference in logic is a reasoning process that leads to a logical judgment or conclusion based on available evidence, information, or facts.
What distinguishes immediate inference from mediate inference?
Immediate inference occurs when a conclusion is drawn directly from a premise, while mediate inference requires more than one premise in logic.
What is conversion in logic?
Conversion in logic takes place when the subject and predicate terms of a standard-form categorical proposition are interchanged.
What are the terms used to describe the propositions involved in conversion?
The standard-form categorical proposition being converted is called the convertend, while the proposition that evolves from the conversion is known as the converse.
Which types of categorical propositions is conversion valid for?
Conversion is valid for E and I propositions.
In what circumstance is conversion possible for an A proposition?
Conversion for an A proposition is only possible by limitation.
Is conversion valid for O propositions?
No, conversion is completely invalid for O propositions.
What is obversion in logic?
Obversion in logic occurs when the quality of a standard-form categorical proposition is swapped from affirmative to negative or vice versa, and the predicate of the proposition is changed to its complement.
What are the terms used to describe the propositions involved in obversion?
The standard-form categorical proposition being obverted is called the obvertend, and the proposition that evolves from obversion is called the obverse.
Which types of propositions can be obverted into each other?
An A proposition can be obverted into an E proposition, and vice versa. Similarly, an I proposition can be obverted into an O proposition, and vice versa.
Are the obvertend and obverse logically equivalent?
Yes, if an A proposition is obverted to an E proposition, or an I proposition is obverted to an O proposition, and vice versa, they are considered logically equivalent.
What is contraposition in logic?
Contraposition in logic is the process of inferring a new proposition by interchanging the subject and predicate terms of a given standard-form categorical proposition and replacing them with their complements.
What are the terms used to describe the propositions involved in contraposition?
The standard-form categorical proposition to be contraposed is called the contraponend, while the new proposition formed from the process is called the contraposit.
Which types of propositions can be contraposed for logical equivalence?
A and O propositions can be contraposed if the truth value must be completely preserved.
What additional step is required for contraposing an E proposition?
For an E proposition, the quantifier must be changed from “No” to “Some” after swapping the subject and predicate terms.
