Moral dilemmas — balancing one right action against another — are a ubiquitous feature of 21st-century life. However unavoidable, though, they are not unique to our modern age. The challenge of accommodating conflicting needs figured as prominently in the lives of our human ancestors as it does for us today.

Many psychologists and social scientists argue that natural selection has shaped cognitive systems in the human brain for regulating social interactions. But how do we arrive at appropriate judgments, choices and actions when facing a moral dilemma — a situation that activates conflicting intuitions about right and wrong?

An influential view claims that certain dilemmas will always confound us, because our minds cannot reach a resolution by weighing the conflicting moral values against one another. But a new study from UC Santa Barbara and the Universidad del Desarrollo in Santiago, Chile, demonstrates that we humans have a nonconscious cognitive system that does exactly that.

A team of researchers that includes Leda Cosmides at UC Santa Barbara, has found the first evidence of a system well designed for making tradeoffs between competing moral values. Their findings are published(link is external) in the Proceedings of the National Academy of Science.