• Korean Journal of Cognitive Science
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• v.18 no.1
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• pp.35-56
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• 2007

The English language has developed from a language with optional subjecthood Into a language with obligatory subjecthood due to a general reduction of inflections. Two types of subject omission, pro-drop and conjunction reduction, have been reported in the history of English. Old English with rich inflections had both referential pro-drop and conjunction reduction. Middle English with much lesser inflections still witnessed pro-drop and conjunction reduction, but in such a decreasing way that modern English with a loss of inflections developed from Middle English hardly has either pro-drop or conjunction reduction. This paper explores both the phenomena relating to optional subjecthood in Old, Middle, and Modern English in light of the cognitive processes of the universal, hierarchical constraints that are assumed to be inherent in English speakers' cognitive fatuity. It is found that optional subjecthood in Old, Middle, and Modern English is correctly raptured in terms of the distinct rankings of the proposed constraints, and that it is closely related to whether each of Old, Middle, and Modern English has rich inflections.