Abstract: Hypotheses are questions of interest to an observer. Evidence are facts that establish or disprove hypotheses or sub-hypotheses. Inferences are logical links that connect facts to hypotheses as evidence. An argument is a set of facts linked by inferences to support or disprove a given hypothesis. Hypotheses, sub-hypothesis, facts, evidence, inference and arguments are visualized using a plurality of interrelated graphical user interfaces. A main visualization screen includes a fact visualization portion, a hypothesis visualization portion and an argument construction visualization portion. The evidence visualization portion comprises an evidence display portion, an evidence details portion and visualization selection widgets that allow different evidence visualization or marshaling techniques to be applied to visualize the facts.