(1858-1931), British logician, mostly remembered for his Logic, in 3
volumes. Also wrote about mathematical logic and induction.
been widely asserted that Johnson belonged to "the old guard" of British
logicians, that was swept away by Whitehead and Russell's Principia
Mathematica. This is not so: Logic is a quite interesting original
work, though it is true that it understands the term "logic" in a wider sense
than became normal in the 20th century in mathematics and philosophy, namely
as comprising (parts of) epistemology, methodology and philosophy of science,
and also true that Johnson, although he was quite competent to do so, avoided
the formalisms that were so characteristic of mathematical logic.
He also had an original take on induction, in an essay that seems to have
inspired both Keynes and Broad to similar ideas, though again in the Logic
Johnson considers various other forms of induction than can be comprised under
generalizing from a sample to a population.
Interestingly, some of the new terminology Johnson introduced in his
Logic - "determinable" and "determinate", "continuant", "occurent",
"ostensive definiton" - was rather widely used in 20th C analytic philosophy.