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Who was the first to write proofs in this fashion?

enter image description here

By ``in this fashion'' I mean, using three columns, which go like:

Line number. Premise or assertion. Justification.

Line number. Premise or assertion. Justification.

Etc.

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    $\begingroup$ The specimen above is so-called Fitch-style; see Frederic Brenton Fitch, Symbolic Logic: An Introduction (Ronald Press, 1952) $\endgroup$ Jun 19, 2023 at 11:05
  • $\begingroup$ @MauroALLEGRANZA Fitch-style proofs seem close, but don't they involve a sort of indentation that the example doesn't have? $\endgroup$
    – Noah J
    Jun 22, 2023 at 19:40

1 Answer 1

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Whitehead & Russel, Principia Mathematica (1910) is pretty much like this.

w&r

The justifications are on the left, and only certain lines are numbered.

But I doubt it is the first.

Compare Frege's notation for first-order logic (1879):

frege

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  • $\begingroup$ Thank you! Do you have any idea who is the first to number every premise and assertion and number and justify every assertion, without exception? I would suspect that this would happen after Russell and Whitehead, but is there anyone earlier than (say) Irving Copi? $\endgroup$
    – Noah J
    Jun 19, 2023 at 10:58

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