How does Plato’s dialogue Meno argue that some knowledge is innate?

In the Meno, Plato addresses the paradox of inquiry: if one does not know what a thing is, how can one search for it or recognize it upon finding it? To resolve this, Plato argues that knowledge is not acquired through sense experience, which he deems unreliable, but is instead "recollected" by the soul from a previous existence.123

Plato demonstrates this theory through a geometrical experiment involving a slave boy who has never received formal instruction. By guiding the boy with specific questions, Socrates shows that the boy can arrive at correct mathematical conclusions. Plato posits that because the boy was able to "discover" these truths without being taught, the knowledge must have been latent within him all along.1

This argument serves as a foundational pillar of rationalism, suggesting that certain fundamental concepts—such as equality or mathematical truths—are innate rather than derived from the physical world. While the specific mechanism of reincarnation is largely rejected by modern philosophy, the core idea that humans possess latent, innate knowledge remains influential in understanding how we acquire complex systems like language.21