The origin of pleonastic that can be traced back to Old English where it could appear in syntactic constructions consisting of a preposition + demonstrative pronoun (i.e. for þy þat, for þæm þe) or a subordinator (i.e. oþ þat). Its diffusion with other subordinators is considered an early Middle English development as a result of the standardization of this item as the general subordinator in the period, which motivated its use as a pleonastic word in combination with all kinds of conjunctions (i.e. now that, gif that, when that, etc.) and prepositions (i.e. before that, save that, in that) (Fischer 1992: 295). Its use considerably increased in late Middle English, reaching its climax in the 16th century. In the 17th century, however, its use rapidly declined, to such an extent that it was virtually obliterated at the end of that same century (Rissanen 1999: 303-304). The list of subordinating elements includes relativizers (i.e. this that), adverbial relatives (i.e. there that) and a number of subordinators (i.e. after, as, because, before, beside, for, if, since, sith, though, until, when, while, etc.
The decline of pleonastic that, however, is not a simultaneous process with all these subordinators insofar as the subordinator for seems to have retained this pleonastic item longer than other conjunctive words. In the light of this, the present paper has been conceived with the following objectives: a) to analyse the use and distribution of pleonastic that in a corpus of early English medical writing (in the period 1375–1700); b) to classify the construction in terms of the two different varieties of medical texts, i.e. treatises and recipes; and c) to assess the decline of the construction with the different conjunctive words. The data used as sources of evidence come from The Corpus of Early English Medical Writing, i.e. Middle English Medical Texts (MEMT for the period 1375–1500) and Early Modern English Medical Texts (EMEMT for the period 1500–1700).