Specifically for the material implication if possible. Who was the first to use a truth table for this and justify its validity?
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2really, all a truth table is, is a definition.– robert bristow-johnsonCommented Jun 10, 2016 at 0:52
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4@robertbristow-johnson But it had to originate from somewhere, and have a justification behind it.– IgnorantCuriosityCommented Jun 10, 2016 at 2:19
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2the question of origin can be applied to anything. definitions don't require justification. they're axioms.– robert bristow-johnsonCommented Jun 10, 2016 at 4:44
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4@robertbristow-johnson The question of origin can be applied to anything, I don't see that as a problem. As for justification, there must be a reason for the definition. That is what I am looking for.– IgnorantCuriosityCommented Jun 10, 2016 at 14:44
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2@robertbristow-johnson In mathematics, definitions and axioms are not the same. Axioms are the foundation for a theory, while definitions are merelyhandy abbreviations.– jjackCommented Jan 6, 2018 at 9:07
1 Answer
You can see:
- Irving Anellis, The Genesis of the Truth-Table Device (2004)
as well as:
- Irving Anellis, Peirce's Truth-functional Analysis and the Origin of the Truth Table (2012).
Before Bertrand Russell (Harvard logic course: 1914) and Ludwig Wittgenstein (Russell and Wittgenstein's manuscript dated 1912; see also: Tractatus (1921), 4.31 and 4.442 for material implication), Charles Sanders Peirce and his followers must be credited.
See Christine Ladd-Franklin, “On the Algebra of Logic”, in Charles Sanders Peirce (editor), Studies in Logic (1883), page 17-on; see pages 61-62.
In Whitehead and Russell's Principia (page 115), we have a description of the truth-functional semantics of connective : not, if..., then..., and, or (but not in tabular form).
The modern tabular form is present in E.Post, Introduction to a General Theory of Elementary Propositions (1921), §2 Truth table development, with explicit reference to W&R's Principia (see footnote 6).
The verbal" description of conditional is in Frege's Begriffsschrift.
But it was already verbally stated in Ancient Stoic Logic with the so-called philonian conditional; see Sextus Empiricus, Πρὸς μαθηματικούς (Pros mathematikous) Book VIII, 113:
Philo, for example, said that the conditional is true when it does not begin with a true proposition and finish with a false one, so that a conditional, according to him, is true in three ways and false in one way. For when it begins with a true one and finishes with a true one, it is true, as in “If it is day, it is light.” And when it begins with a false one and finishes with a false one, it is again true – for example, “If the earth flies, the earth has wings.”