Philosophers have debated for years whether we deliberately make each of the many decisions we make every day, or if our brain does it for us, on autopilot. Neuroscientists have shown, for example, that neurons in the brain initiate our response to various stimuli milliseconds before we’re even aware that we’re taking such an action.

This heady debate has hit a very practical road in the past decade: whether individuals who commit crimes are actually responsible for them. Lawyers have argued in court that if the brain determines the mind, then defendants may not be responsible for their transgressions.

Michael Gazzaniga, director of the SAGE Center for the Study of Mind at the University of California, Santa Barbara, is at the forefront of the research into free will, and its implications in courtroom trials and in the expectations of different societies. His thoughts and proclamations are captured in an engaging video called Free Will, created by Joseph LeDoux, a well-known expert on the emotional brain at New York University. The video is the second in a series he is putting together with director Alexis Gambis called My Mind’s Eye. (The first episode featured Ned Block on the mind-body problem.) They have given Scientific American the chance to post these videos first, on our site.

How Free Is Your Will? An interview with Michael Gazzaniga from Imaginal Disc on Vimeo.

The conversation between LeDoux and Gazzaniga (who is also an editorial adviser to Scientific American) runs about 12 minutes, and Gambis has inserted some compelling imagery, including clips of creepy old movies in which scientists probe the brains of live people. The film then morphs into a four-minute music video of the song “How Free Is Your Will?,” performed by LeDoux’s band, the Amygdaloids. A few highlights of the interview, offered freely, by me:

2:55 Split-brain patients. Gazzaniga explains what has happened to these people, and what they can teach us about how we make decisions.

6:50 Personal responsibility. This is the crux of the argument about whether responsibility for our actions lies in the neuronal structures of the brain or in our conscious minds, and whether biological mechanisms or society’s norms are most important in defining acceptable behavior. “There’s no reason to not hold people accountable for their actions,” Gazzaniga maintains. He then discusses how society can more intelligently decide on what to do with people who violate its rules.

9:05 Criminal trials. Gazzaniga discusses problems in referring to brain scans in courtroom trials and in sentencing people who are convicted, and considers the effectiveness of capital punishment, given what we know about free will.

12:00 Music video of “How Free Is Your Will?”

Further reading, suggested by Michael Gazzaniga:

For the Law, Neuroscience Changes Nothing and Everything. Joshua Greene and Jonathan Cohen in Philosophical Transactions of the Royal Society B, 359, 1775-1785; 2004.

The Law and Neuroscience, Michael S. Gazzaniga in Neuron, 60:412-415; 2009.

Who’s in Charge? Free Will and the Science of the Brain. Michael S. Gazzaniga. Ecco, Harper Collins, New York; 2011.

Neuroscience in the Courtroom, Michael S. Gazzaniga in Scientific American, April 2011.

A Primer on Criminal Law and Neuroscience: A Contribution of the Law and Neuroscience Project. Oxford Series in Neuroscience, Law, and Philosophy; eds. Stephen J. Morse and Adina L. Roskies; 2013.

Image from this video courtesy of Imaginal Disc