Abstract
This article examines the frequency and discourse functions of 752 active transitive clauses in a 66,500-word corpus of sixteen research articles in the physical sciences. The overall rate of actives was only 34 percent; the rates were lowest in the Methods (12%) and Abstracts (27%), higher in Introductions (41%) and Results (40%), and highest in Discussions (44%) and Conclusions (52%). The active was often required because of the principle of end-weight. Throughout the research article actives with “real world” grammatical subjects were used to state “scientific truths.” The most prominent other functions tended to vary from section to section and to correlate somewhat with the semantic subcategory of the grammatical subject. Active clauses with human subjects were used to cite research and to introduce metadiscourse, while ones with discourse subjects were used to introduce graphics, and ones with research process subjects and research product subjects were used to make evidential statements about results.