Socrates, the ancient Greek philosopher, never wrote things down. He warned that writing undermines memory – that it is nothing but a reminder of some previous thought. Compared to people who discuss and debate, readers “will be hearers of many things and will have learned nothing; they will appear to be omniscient and will generally know nothing.”

These views may seem peculiar, but his central fear is a timeless one: that technology threatens thought. In the 1950s, Americans panicked about the possibility that advertisers would use subliminal messages hidden in movies to trick consumers into buying things they didn’t really want. Today, the U.S. is in the middle of a similar panic over TikTok, with critics worried about its impact on viewers’ freedom of thought.

To many people, neurotechnologies seem especially threatening, although they are still in their infancy. In January 2024, Elon Musk announced that his company Neuralink had implanted a brain chip in its first human subject – though they accomplished such a feat well after competitors. Fast-forward to March, and that person can already play chess with just his thoughts.