He first presents a mathematical proof, inspired by Bell's theorem, that a contradiction results if one assumes: (a) the principle of local causes, (b) an elementary theorem of quantum mechanics, and (c) what Stapp calls the «assumption of contrafactual definiteness» (roughly the assumption that measuring
procedures which were not carried out would have yielded definite results had they been carried out and that these possible but unrealized results are restricted by the
same laws that apply to the results of actual
measurements).
With land stations we have the option of using only temperature changes between
measurements from the
same station and disregarding by some
procedure stations that are particularly suspect.