This paper investigates the distinction between determining and modifying expressions that played an important role in the Brentano School. The focus lies on how the distinction is applied to adjectives by Anton Marty and Kazimierz Twardowski. In "heavy gun', "heavy' plays a determining role: heavy guns are guns; in "fake gun', "fake' plays a modifying role: fake guns are no guns at all. According to Marty and Twardowski, when a modifying adjective is combined with a noun, it shifts the meaning of the noun. This paper rejects this proposal and proposes a better account which was developed by Bernard Bolzano: the difference between determining and modifying adjectives must be understood in terms of how their meanings figure in meaning analyses of adjective-noun combinations.