Dunn has proved that an inconsistent field with (a) a pair of classically distinct real numbers x,y identified x=y, and (b) the resulting theory closed under the laws of classical fields, then we have that every real number is provably identical to every other  (r,s)(r=s). The proof is simple: from x=y we have 0=(y-x), then both sides can be multiplied by any factor we like to get 0=r and 0=s for any r,s. Hence by Leibniz Law r=s. This is avoidable only by restricting functional substitution. How then is it prevented in the present construction? Especially in light of the (unproved) result of the preservation of function values P8? Is it because the only inconsistency contemplated in this construction is simply adding ~(x=y) for some classically identical x=y? If so, doesn’t this restrict its usefulness? There are of course inconsistent constructions which prevent Dunn’s argument, such as Mortensen’s.

Inconsistent Mathematics

 C.E. Mortensen

https://books.google.co.il/books?id=KYDrCAAAQBAJ&dq=Dunn+has+proved+that+an+inconsistent+field&source=gbs_navlinks_s

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