Definition of subcontrary in English:

subcontrary

adjective

dated
  • Denoting propositions which can both be true, but cannot both be false (e.g. some X are Y and some X are not Y).

    • ‘Similarly, ‘some unicorns have horns’ and ‘some unicorns do not have horns’ are both regarded as false, and so they are not subcontrary.’’
    • ‘Paradox seems to arise when conditional statements have subcontrary statements as antecedent and consequent.’
    • ‘It follows that high or low probability are contrary to necessity of opposite polarity, and subcontrary to possibility of opposite polarity.’
    • ‘In traditional logic the I and O statements are considered subcontrary to one another; in other words, they can both be true at the same time, but cannot both be false.’
    • ‘The particular statements: I and O are subcontrary: ‘Some S are P’ and ‘Some S are not P’ can be true, but both cannot be false.’

nounsubcontraries

dated
  • A subcontrary proposition.

    • ‘Again, I and O propositions are subcontrary, but not contrary or contradictory.’
    • ‘The case of subcontraries will be revealed to include an unjustified presupposition in the section concerning the modern square of opposition.’
    • ‘Given that traditional logicians did think the subcontraries have ‘existential import’, how do we resolve the apparent contradiction?’
    • ‘Particular statements are subcontraries. ‘Some man is just’ and ‘some man is not just’ cannot be false together’

Origin

Late 16th century from late Latin subcontrarius, translation of Greek hupenantios.

Pronunciation

subcontrary

/sʌbˈkɒntrəri/