Identity area
Reference code
Add. MS c/94/64
Title
Letter from W. E. Johnson to Henry Sidgwick
Date(s)
- 14 Mar. 1894 (Creation)
Level of description
Item
Extent and medium
2 docs
Context area
Name of creator
(1838-1900)
Repository
Archival history
Immediate source of acquisition or transfer
Content and structure area
Scope and content
Admits that he may have spoken too strongly [see 94/63] 'in implying that the method of Reductio ad absurdum would necessarily be formulated as If P then Q If P then not Q _ not P' Refers to two enclosed examples (included) 'in which this would seem the natural analysis.' Claims to be unable to 'find any good case (except from Geometry) of the method.' Would like to send to Sidgwick 'a good case of such an argument', but cannot find one. Letter accompanied by examples of two of Euclid's proposals in which the method of reductio ad absurdum is used, both involving geometry.