A causal map can be defined as a network consisting of links or arcs between nodes or factors, such that a link from factor C to factor E means that someone (P) believes that C in some sense causally influences E. Every link represents one causal claim.

Alternatively we can say that such a link means that there is some evidence (P) that C in some sense causally influences E (seeWe can reason about causal maps using a logic of evidence).

• Causal maps encode a belief about a usually partial causal influence of C on E, and only in special cases encode total or exclusive causation such that C entirely determines E or is the cause of E.
• Encoding a claim (like ‘the heavy rains were one reason the harvest was worse than usual’) in causal mapping does not require us to make any judgement about the quality of the evidence or the ability of the source to correctly judge that this link was causal (although we can add this information if we want).