In this paper, an argument for objectivism, advanced by Stjepan Zimmermann in 1934 and 1942, is thoroughly analyzed and examined. Here, in connection with this argument, objectivism, being restricted to the domain of experiential objects in the perceiver’s mind (i. e. to the perceiver’s sensations, percepts, experiences and experiential self), including various propositions about those objects, consists in the following three theses: first, those objects (the perceiver’s sensations, percepts, experiences and experiential self) exist independently of the perceiver’s propositions about them; second, the truth values of the propositions concerning those objects rest solely on the objects themselves and are fully independent of the perceiver; third, those propositions admit of no relativism regarding their truth values. Zimmermann’s argument for these theses proved unacceptable because it entirely overlooked both the constitutive part the perceiver (i.e. the perceiver’s sensory, perceptual, emotional and introspective constitution) plays in the very formation of his/her own sensations, percepts, experiences and experiential self, and the normative role the perceiver plays regarding the truth values of the propositions about his/her own sensations, percepts, experiences and experiential self.