Unconditional altruism is an enduring puzzle for evolutionary approaches to social behavior. In this paper, we argue that costly signaling theory, a well-established framework in biology and economics, may be useful to shed light on the individual diVerences in human unconditional altruism. Based on costly signaling theory, we propose and show that unconditional altruistic behavior is related t...

According to orthodox (Kolmogorovian) probability theory, conditional probabilities are by definition certain ratios of unconditional probabilities. As a result, orthodox conditional probabilities are undefined whenever their antecedents have zero unconditional probability. This has important ramifications for the notion of probabilistic independence. Traditionally, independence is defined in t...