[tgv]

Idk who they are, but have they ever learned a second language? It's probably just a gimmicky claim that got them a bit of fame (or infamy), and they stuck by it because of their career. I doubt they can present evidence.

And I don't mean: here's someone who was exposed to a large amount of English, and can now say a bunch of three word sentences. That's cheating. No, I want to see a large, representative group of people that haven't had any feedback on their speaking and writing during their learning reach almost error free, near-native fluency for a totally unfamiliar language (i.e., not an Englishman being exposed to French or a Mandarin speaker to Cantonese).

Edit: I looked up Krashen, but that looks like a hopeless case of academic hubris. E.g., this (http://www.sdkrashen.com/content/articles/why_dont_educators...) is just full of it. And he got influence on education with his absurd ideas.