Everyone is misunderstanding @nickcammarata. He's not saying polysemanticity literally never happens! (As he points out, poly vs mono depends on your POV.) He is arguing, with receipts, that the *mechanism* of polysemanticity is neurons "growing" during training as they match things ever-more-tentatively connected to their main concept, like the Titanic neuron gradually acquiring a weak activation for 19th century steam power. (You see the connection, right?) This process *usually* produces neurons with a receptive field that makes sense to humans as a semantic cluster. (The brain does this too! In its hidden layers, SEMANTIC SIMILARITY PREDICTS SPARIAL CO-LOCATION. WHY SHOULD THIS BE?) It doesn't mean the neuron has one "feature". Features are ill-defined, like a coastline. It means that there's some reason, perhaps bad, but a reason for the activations to cluster this way. You can see this in biology too. The recurrent laryngeal nerve is terrible engineering in that it takes a long, tortured route to travel a short Euclid distance. Yet you can see how the nerve got to have the shape it does. It makes sense. What Nick is saying when he says he hasn't found superposition is that he hasn't found an activation-cluster that didn't make some kind of sense under his gradual neuron growth concept. Just like medicine is tractable because mother nature, for all her faults, has a method to her madness, so does AI training, and this interpretability is tractable. Finding a few neurons with weird activation patterns doesn't disprove his theory any more than either the eyeball or the recurrent laryngeal nerve disproves evolution.