Scientific reasoning includes deciding whether information is relevant to explaining an event. In some cases, seeinginformation as relevant requires having a background theory or explanation that can make sense of the information. Collegestudents were shown a possible explanation for an event, along with two pieces of possibly relevant information (Info1 andInfo2), and one of two possible alternative explanations (Alt1 or Alt2). Info1 was seen as more relevant when Alt1 rather thanAlt2 was presented; Info2 was seen as more relevant when Alt2 rather than Alt1 was presented. In addition, relevance ratingsof the information increased as did initial ratings of the Alternative. People from different backgrounds might bring with themdifferent alternative theories that can hinder the understanding of why some information is relevant and other information not. Inaddition, finding the initial alternative compelling might enable people to better assess the relevance of additional information.

Philosophers of science have long argued that when evaluating explanations, we do not consider ideas in isolation. Instead, we possess an integrated web of information that comprises the context we consider when weighing evidence about any component of this web. In this paper, we provide empirical evidence that theories are considered in context by demonstrating that non-scientists change the strength of their belief in both of two alternative theories, even when only given information about one of these hypotheses. In addition, we seek to identify and describe some of the types of information people use in evaluating theories. Information about mechanism, inferences that discriminate between two explanations, and information about closely related situations in which the target factor operates as a mechanism can all significantly affect ratings of two rival explanations.