Descartes' Error

In the seventeenth century, the French philosopher René Descartes summed up an idea that shaped Western thought: I think, therefore I am. For him, the mind, made of thought, was one thing; the body, made of matter, was another. Reason on one side, body and feelings on the other, with reason in charge. This split became known as dualism.

In 1994, the Portuguese neurologist Antonio Damasio published Descartes' Error to argue that this division doesn't hold up. Drawing on patients with brain lesions, he argues that reason doesn't work well without emotion, and that the mind depends on a body that feels. The error in the title is this cut between thinking and feeling.

The book is more technical than many popular science books, with names of brain areas and clinical cases. But the thread is simple: people who lose the ability to feel also lose part of the ability to decide. We'll go through the cases, the main ideas, and the criticisms science has raised since then.

The story begins in 1848, in the U.S. state of Vermont. Phineas Gage, 25, was a foreman on a railroad construction job and used an iron bar about three feet long to tamp gunpowder into holes in the rock. An unexpected explosion launched the bar, which went in below his left eye and came out through the top of his skull.

Gage survived, and he could talk and walk. According to the doctor who treated him, John Harlow, the responsible, even-tempered man became impatient, rude, and unable to stick to plans. To his friends, he was no longer the same Gage. Damasio and his wife used the preserved skull to reconstruct the bar's path by computer and concluded that it hit the lower frontal region of the brain.

The lesson would be that parts of the brain tied to emotion and social judgment can be damaged without harming speech, memory, and intelligence. It's a powerful story, but the records are scarce and have been embellished over time. It opens the book as a warning that thinking well and behaving well are not the same thing.

The second case is a patient named Elliot, a man who was successful in business and in his family life. He had a tumor near his forehead that pressed on the frontal regions of the brain, and surgery removed the tumor along with a bit of healthy tissue around it. Tests afterward showed normal intelligence, memory, and language.

But Elliot's life fell apart. He lost his job, made bad business deals, went bankrupt, and got divorced. He would spend hours analyzing details without reaching any conclusion: to schedule his next appointment, for example, he compared days, traffic, and weather for so long that a simple decision became impossible. He talked about his own tragedies coldly, as if they had happened to someone else.

For Damasio, the point is that Elliot knew how to reason but didn't feel the weight of the alternatives. Without the sense that one option is better or worse, they all looked alike. The case suggests that you can have plenty of logic and, without feeling anything, be unable to choose. It's a single case, which limits the conclusions, but it's the doorway into the book.