Notational conventions. The introduction of superfluous elements into algebra for purposes of balance and homogeneity. Rules of algebraical procedure. The three laws of thought: identity, contradiction, and excluded middle. Logic and the uses of ordinary language. Aristotle's propositional forms.
Aristotle, Contradiction principle of (see also Laws of thought), Excluded middle principle of (see also Laws of thought), principle of identity (see also Laws of thought), Logic (modal see Modality), Ordinary language