The principles of science : a treatise on logic and scientific method / by W. Stanley Jevons.

  • Jevons, William Stanley, 1835-1882.
Date:
1874
Catalogue details

Licence: Public Domain Mark

Credit: The principles of science : a treatise on logic and scientific method / by W. Stanley Jevons. Source: Wellcome Collection.

    57/488 (page 37)
    S = of specific gravity io-5, T = melting above iooo°C, Y = good conductor of heat and electricity, then we can form a combined term PQRSTY, which will denote ' a white monovalent metal, of specific gravity 10*5, melting above iooo°C, and a good conductor of heat and electricity/ There are many grammatical rules or usages concerning the junction of words and phrases to which we need pay no attention in logic. We can never say in ordinary language 'of wood table/ meaning 'a table of wood/ but we may consider ' of wood' as logically an exact equivalent of ' wooden'; so that if X = of wood, Y = table, there is no reason why, in our symbols, XY should not be the correct term for ' table of wood/ In this case indeed we might substitute the corresponding adjective 'wooden/ but we should often fail to find any adjective answering exactly to a phrase. There is no single word which could express the notion ' of specific gravity 10*5 ': but logically we may consider these words as forming an adjective ; and denoting this by S and metal by P, we may say that SP means 'metal of specific gravity 10*5.' It is one of many advantages in these blank letter-symbols that they enable us completely to abstract all grammatical peculiarities and fix our attention solely on the purely logical relations involved. Investigation will probably show that the rules of grammar are mainly founded upon traditional usage and have little logical signification. This indeed is suffi ciently proved by the wide grammatical differences which exist between languages where the logical foundation must be the same.