ABSTRACT
Conditionalsentencespropercontaintwopropositionsofwhichone conditionsthevalidityoftheother:iftheconditioningpropositionis validated,theconditionedonewillbesoalso;ifitisnot,theconditionedpropositionisalsoinvalidated.In'ifhecomestomorrow,Iwill talktohim',theproposition'Iwilltalktohim'isaconditionedone whichwillnotbevalidatedunless'hecomes'turnsouteventuallyto bevalid.Inthestrictsense,therefore,aconditionalsentencecanonly besitedinthefuture,sincetheopen-endedpossibilityofaproposition beingeithervalidatedorinvalidatedcannottrulyexistinthepast; whenanapparentlyconditionalsentenceissitedinthepastaswith'if hecameyesterday...',itsopen-endednatureappliestothespeaker's knowledgeofthefact,nottothefactitself,whichisnecessarilypositivelydeterminedonewayortheother.Buttherearemanytypesof sentencewhichdonotconformtothestrictdefinitionofaconditional, asgivenabove,yetshowsufficientstructuralsimilaritytobegrouped togetheras'conditionalstructures'.
