Peikoff says on 173-174 that “truth” is an epistemological concept pertaining to a relationship between consciousness and reality, and that something is true if it logically integrates into your contextual knowledge of reality (correct me if I’m wrongly paraphrasing). In his example, the belief that Type-A blood is always compatible with Type-A blood was true in the context of knowledge preceding the discovery of the RH factor, because knowledge of the incompatibility caused by RH wasn’t yet available and would require omniscience without the preceding contextual discovery of the basic blood types.
This seems to create a situation in which a piece of knowledge (“Type-A blood is compatible with people who have Type-A blood”) is at once true and not true. It’s “true” in Peikoff’s epistemological sense, as in “a valid conclusion in context,” but it’s untrue in the popular sense of the word “true”, meaning it actually accords with reality – some Type-A blood is not compatible with some Type-A blood.
I always thought the concept “true” existed to identify something’s correspondence to actual reality, not one’s temporary contextual understanding of it. Do we need two separate concepts for these things? What’s the difference between “valid” and “true” in Peikoff’s usage? Are we seriously saying that knowledge later proved incorrect was “true” while we didn’t have the disproving information, or have I badly misunderstood Peikoff’s point here?
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