[FOM] Simple historical question

[Neil Tennant]

> To whom should we rightly give first credit for the result/observation 
> that Th(N,0,S,+,*,<) is undecidable?

Perhaps the answer is to be found in section II.5 (beginning on p.60) of 
A. Tarski, A. Mostowski and R.M. Robinson, Undecidable Theories,
North-Holland, Amsterdam, 1953.

The footnotes display the required degree of historical sensitivity.
Theorem 9 and Corollary 10 cover a wide range of systems. For the special
case of Th(N) [called sans-serif 'N' in the monograph], the result is
attributed to Tarski's famous paper on truth (the German version in
Studia Philosophica), 'in particular footnotes 88 and 95'.

Neil Tennant