Hismathematicswasnotrigorous(itcouldnotbeasthemathematicaltechniquesnecessarytomakeitsohadnotbeendevelopede.g.measuretheoryandaxiomaticprobability)although,hisresultswerebasicallycorrect.
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His mathematics was not rigorous (it could not be as the mathematical techniques necessary to make it so had not been developed e.g. measure theory and axiomatic probability) although, his results were basically correct.