The Book of Days (1864) by the Scottish author Robert Chambers reports a curious legal case: in 1457 in the town of Lavegny, a sow and her piglets were charged and tried for the murder of a partially eaten small child. After much deliberation, the court condemned the sow to death for her part in the act, but acquitted the naive piglets who were too young to appreciate the gravity of their crimes.
Subjecting a pig to a criminal trial seems perverse through modern eyes, since many of us believe that humans possess an awareness of actions and outcomes that separates us from other animals. While a grazing pig might not know what it is chewing, human beings are surely abreast of their actions and alert to their unfolding consequences. However, while our identities and our societies are built on this assumption of insight, psychology and neuroscience are beginning to reveal how difficult it is for our brains to monitor even our simplest interactions with the physical and social world. In the face of these obstacles, our brains rely on predictive mechanisms that align our experience with our expectations. While such alignments are often useful, they can cause our experiences to depart from objective reality—reducing the clear-cut insight that supposedly separates us from the Lavegny pigs.