Determined is based on the philosophical concept of determinism, also referred to as causal determinism or causality, and its ramifications for free will, society, and social ethics. Determinism holds that every event that occurs is driven by preceding circumstances—every effect is caused. Indeterminism, in contrast, states that not all events are affected by antecedent conditions—or some effects are causeless. While the concept of determinism first emerged in ancient Greece, it reached mathematical maturity in the 1700s (“Causal Determinism.” Stanford Encyclopedia of Philosophy, 2003). Despite its long history, no consensus has been reached as to whether the universe is deterministic, particularly in regard to human behavior. As Sapolsky notes throughout Determined, determinism is incompatible with free will, and humans experience an inherent sense of free will. These facts make it more challenging for people to accept the concept of determinism as it relates to human behavior.

Numerous scientists have made cases both for and against causal determinism. Sapolsky notes several modern scientists who represent diverse thinking on the topic. Other prominent supporters of determinism include Max Planck, who was a founder of the quantum theory discussed in Chapters 9 and 10, and Albert Einstein, the well-known theoretical physicist who established the theories of general and special relativity as well as contributing to quantum mechanics.