Distrust is not always the complement of trust

We believe that distrust can be as important as trust when agents are making a decision. An agent may not trust a source because of lack of positive evidence, but this does not necessarily mean the agent distrusts the source. Trust and distrust have to be considered as two separate concepts which can coexist. We are aware that an adequate way to take this fact into account is by considering explicitly not only the agent’s degree of trust in a source but also its independent degree of distrust. Explicitly taking distrust into account allows us to mark a clear difference between the distinct notions of negative trust and insufficient trust. More precisely, it is possible, unlike in approaches where only trust is explicitly accounted for, to “weigh” differently information from helpful, malicious, unknown, or neutral sources.