RAG is Just Bayesian Inference: The Simple Truth Behind AI’s “Magic” 🎯
Last Updated on November 13, 2025 by Editorial Team
Author(s): AbhinayaPinreddy
Originally published on Towards AI.
The Surprising Discovery That Changes Everything
Here’s something wild: every time ChatGPT or Claude uses documents to answer your questions, they’re using a mathematical formula from 1763.
This article explains how Retrieval-Augmented Generation (RAG) works, emphasizing that it relies on Bayes’ Theorem, a formula that is over 260 years old and not a modern breakthrough. It discusses how AI, when presented with documents, can retrieve and augment information to improve answers compared to relying solely on pre-existing knowledge. The author illustrates the importance of understanding this foundation of AI to enhance user interactions and development in AI tools.
Read the full blog for free on Medium.
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