Explanations are social, and when people try to explain something, they usually seek input from others. We present a simple theory of how people use the explanations they encounteras clues to the broader landscape of possible explanations,informing their decision to exploit what has been found orexplore new possibilities. The challenge of coming up withnovel explanations draws people to exploit or imitate appealing ones (information cascades); this draw increases as lessappealing alternatives become more distant (the “strawman”effect). Conversely, pairs of low-quality explanations promoteexploratory behavior or long-leaps away from observed attempts, and pairs of divergent high-quality explanations canlead to merging and syncretism. We use a transmission-chainexperiment to test, and confirm, these predictions. Intriguingly,we also find that while people imitate good explanations, theirimitations often fall short in quality. Our work provides newinsight into how collective exploration can be promoted, orstalled, by implicit information about what is yet to be discovered.