1. This paper proposes a generic method for identifying elements in a domain that can be used as trust evidences. As an alternative to external infrastructured approaches based on certificates or user recommendations we propose a computation based on evidences gathered directly from application elements that have been recognized to have a trust meaning. However, when the selection of evidences is done using a dedicated infrastructure or user's collaboration it remains a well-bounded problem. Instead, when evidences must be selected directly from domain activity selection is generally unsystematic and subjective, typically resulting in an unbounded problem. To address these issues, our paper proposes a general methodology for selecting trust evidences among elements of the domain under analysis. The method uses presumptive reasoning combined with a human-based and intuitive notion of Trust. Using the method the problem of evidence selection becomes the critical analysis of identified evidences plausibility against the situation and their logical consistency. We present an evaluation, in the context of the Wikipedia project, in which trust predictions based on evidences identified by our method are compared to a computation based on domain-specific expertise.