It is well known in the literature on security dilemma theorising that John Herz coined the concept in the early 1950s with Herbert Butterfield developing a very similar concept at the same time. What is less well appreciated is that Butterfield powerfully argued in his 1951 book History and Human Relations that there was no prospect of state leaders and diplomats overcoming the dynamics of mutual suspicion and distrust that created what he had chosen to call a condition of ‘Hobbesian fear.’ Herz parted company with Butterfield on this fundamental question, considering that two adversaries could come to appreciate that what they perceived as the other’s hostile behaviour was a defensive response to their own actions. This article revisits this fundamental question that divided the pioneer theorists of the security dilemma as to whether better mutual understanding between potential rivals might be the key to mitigating fear-based hostility. The article discusses this question in relation to Herz’s ideas about surviving the nuclear age, and shows how he believed that knowledge of the security dilemma was critical if the superpowers were to mitigate their security competition. Having examined how far the end of the Cold War supports Herz’s position, the article concludes by showing how Herz became increasingly disillusioned that the United States was capable of acting to mitigate the security dilemma in the post-Cold War world.