Transitivity of identity
Encyclopedia : T : TR : TRA : Transitivity of identity
The transitivity of identity is the logical principle that, if a=b, and b=c, then a=c.
For example, if you know that the Morning Star is the same thing as the Evening Star, and you know that the Evening Star is Venus, you can conclude that the Morning Star is Venus.
The transitivity of identity (like rules concerning identity generally) is not always valid in epistemological, modal, or otherwise opaque contexts. For example, if Oedipus knows that his wife is Jocasta, and you know that Jocasta is the mother of Oedipus, one may not conclude that Oedipus knows that his wife is his mother.
See also
From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.