Greenspan became acquainted, in 1952, with Ayn Rand, the novelist-philosopher, through his then-wife, Joan Mitchell. Though he admired her commitment to reason, he was a 'logical positivist', and contradicted her continuous certainty, stating that reality could only be discussed in terms of probabilities. Nathaniel Branden called him "The Undertaker", and the name stuck among Rand's disciples. Rand and others admired his mind, but found his commitment to social climbing a bit too keen.