We assess whether an artifact’s design can facilitate recognition of abstract causal rules. In Experiment 1, 152 three-year-olds were presented with evidence consistent with a relational rule (i.e., pairs of same or different blocks activate a machine) using a machine with one of two designs. In the standard-design condition, pairs were placed on top; in the relational-design condition, blocks were placed into openings on either side. Experiment 2 assessed whether this design cue could facilitate adults’ (N=102) inference of a distinct, conjunctive cause (i.e., that two blocks, together, activate the machine). Results of both experiments demonstrate that causal inference is sensitive to design: participants in the design conditions were more likely to infer the a priori unlikely rules. Findings suggest that reasoning failures may result from difficulty generating the relevant rules as cognitive hypotheses, but that artifact design aids causal inference, with clear implications for creating intuitive learning environments.