Descartes’ Error: Emotion, Reason and the Human Brain by António R. Damásio
My rating: 5 of 5 stars

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I’ve joked that there must be a law requiring any author writing a book on neuroscience for a popular audience to tell the story of Phineas Gage. This book is no exception. Its first couple chapters explore the case of Gage in detail. For those who don’t read much on this subject, Phineas Gage was a foreman for a construction company. By all accounts he was a reliable and solid individual, respected by his employees, trusted by his employer, and beloved by his family. Then one day a four-foot tamping rod was blown through his skull – literally, in one side and out the other. One might think that having a chunk of brain skewered out by a steel rod on a gunpowder-fueled ride through the skull would leave one – at best — a glassy-eyed, drooling, catatonic lump. Surely, a steel rod would wreak more havoc than the narrow needle used in lobotomies? However, what makes Gage’s story fascinating is that the injury resulted in no readily apparent disruption in cognitive function. Gage could still speak fluidly. He retained his memories. He could do math at the same level as before. However, this isn’t to say that the hole through his brain left him unchanged. The even temperament that made him an ideal employee and that endeared him to friends and family was gone. Gage became angry and unreliable.

So what is the relevance of the Gage story to Damasio’s book? Quite a lot, actually. Damasio’s book is about emotion, its influence on decision-making, and how bodily states create emotion. In parts two and three of this three-part book, after introducing the reader to the role of the brain in emotion via the cases of those with selective brain damage, Damasio lays out an argument for what he calls the “Somatic Marker Hypothesis” which says that bodily states are what create the sensations that we associate with emotion. The title-referenced error made by Descartes will be apparent to those familiar with Cartesian dualism. Descartes believed there was a dualism between mind and body – i.e. that there was this physical stuff that got us about from place to place, but there were these intangible thoughts and feelings that were matter-independent that were the makings of mind and which were really you (i.e. you think, therefore you are.) Damasio believes that you cannot separate what it feels like to be you from the body and all its hormones, neurotransmitters, vital statistics, neuronal firing, etc.

The book consists of eleven chapters divided into three parts. In the first part, the author lays out not only the case of Gage, but other examples of individuals who had injury or illness in the brain that disrupted emotion and its influence on decision-making. We learn that an unemotional being isn’t like Spock, but instead is paralyzed by indecision. It turns out that it’s emotion that give us a kick, particularly when he have no sound basis on which to make a rational judgement. The second part draws the connection between body and our emotional self, culminating in a description of the Somatic Marker Hypothesis. The final part describes how the Somatic Marker Hypothesis could be tested and where this line of study seems to be going. The book is annotated and has a bibliography as one would expect of a scholarly work – even one written for a popular audience. The book has a few graphics – graphs, charts, and diagrams, but not very many and of a clear and simple nature.

I’d highly recommend this book for anyone interested in the working of the mind. It’s a thought-provoking look at what it means to be an emotional being and challenges our preconceptions about feelings.

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