Abstract
In compiling and testing the diachronic part of the Helsinki Corpus of English Texts, our project group has come across three problems which arise from the use of computer corpora in studies of syntax and vocabulary. While these problems are mainly associated with work on diachronic corpora, they may be universal enough to deserve somewhat more general consideration. They could be called “The philologist’s dilemma”, “God’s truth fallacy”, and “The mystery of vanishing reliability”. The first could be described as pedagogical, the second methodological and the third pragmatic.