 The Contributions also contains valuable epistemological reflections. Since axioms in the objective sense need not be evident to us, Bolzano states, it can and does happen that, at first anyway, we find them less trustworthy than the theorems that are objectively demonstrable from them. We become convinced of their truth not by contemplating them in isolation, but rather by recognizing their role within a deductive system: that is, by seeing that their objective consequences include the theorems we believe to be true but no propositions we take to be false (Bolzano 1810, II, §21, note; Bolzano 2004b: 119). Similarly, even though simple concepts cannot be defined in an objective sense, they may still require definition in the subjective sense, that is, we may need to develop a clear understanding of them. In such cases, our understanding