<p>For all our familiarity with mental processes, their nature remains elusive, and the lessons offered so far by artificial intelligence seem at best incomplete. This reaffirms the need for a conceptually different approach. Recent developments in quantum mechanics, involving nothing larger (or smaller) than tabletop setups, shed light on the issue by showing that events do not always follow a fixed causal order, and that processes exist that are causally non-separable. While experiments have so far preceded theory, fueling debate about the physical interpretation of key results, this mirrors an earlier controversy where results at odds with prevailing paradigms were subsequently vindicated, giving rise to a quantum formalism that is now canonical. In this instance, validation would yield a precise definition of causal agency as an intent-bearing process, the behavior of which is nonrandom, not determined by preceding events, and not derivable from sequential events within the process itself. By focusing on causality rather than on freedom and its interpretive pitfalls, this definition allows to make headway in an old metaphysical discussion.</p>