This paper aims to fill in a long missing piece in the paradigmatic word-formation research: a set of rival affixes whose members are differentiated in meaning. We argue that such a set can be found in English derivational adjectivalization, in the affixal rivalry between the adjectivalizing suffixes -ed and -y. Using the traditional method of doublet comparison (Aronoff 1976, 2020), we reveal that adjectives of the form Xed and those of the form Xy (X standing for the source word) differ in the scale type. Xed adjectives are closed-scale adjectives, but Xy adjectives are totally open-scale adjectives. The scale-type difference explains why Xed adjectives combine with certain degree modifiers, whereas Xy adjectives do not. Furthermore, we show that the rival affixes are doubly differentiated in the deverbal domain in terms of the said output scale type and the input base selection. In this domain, the major sources of the closed-scale -ed adjectives and the open-scale -y adjectives are result and manner verbs, respectively.
