The conj unction of these few general statements can then be adopted as true by fiat, as Hunt sphere, includes was adopted their adoption a conventional circumscription of the meaning of the primitive 'later th a. Adoption of this convention renders a the known truths conventionally true which under ordinary usage are truths essentially involving any logical or mathematical expre ion;, 'later tha ,' or any of the expressions which, like 'event; 'instant,' and 'time, are defined on the basis of the foregoing, a inessentially involving any thing else.