Do you think that input is enough to learn a language?

I have been watching videos of Stephen Krashen, and his ideas seem to me very convincing.

I’m not sure what you’re asking here, so I’ll guess. If I read and listen diligently for several years, I will I not only be able to read and listen well, but also converse and write well, without having done anything other than reading and listening? If that’s your question, my answer is “no”.

To say that massive input is essential to learning a language to a high level is one thing, and just about everybody agrees with that. But to say nothing else is needed, or that nothing else can possibly help you learn, is something else, and I for one don’t believe it.


Depends what we mean by “learn a language”?

Listening and understanding
Actively speaking
Reading and understanding

These are all separate language skills and mastery of one (or both) of the first two in the list doesn’t necessarily imply mastery of the others. One can, for example, be very fluent in speaking a language without being able to read at all - much less write.

Even as regards the first two, the skills possibly aren’t usually on an exact par? Even native speakers (especially children) can perhaps understand much more than they can actively say?

By listening a lot to interesting material, getting a lot of stimulating input, we are building up a hugely valuable skill - the ability to understand the spoken language. If one can do that well it probably isn’t going to be terribly difficult to get into speaking (and reading and writing).

But it may be possible to be very adept at listening and understanding without really being able to speak much? Back in the 60s 70s and 80s the military and Intelligence agencies used to train people whose job it was to listen in to radio traffic in languages like Czech, Russian, etc. From what I’ve heard these guys typically couldn’t speak much!

Well, you can even tell from Steve Kauffman, that in the languages where he just read and listened a lot, he is no good at speaking and writing, even though he obviously reads a tonn of complicated stuff like 19 century novels, political discussions, etc.
So the question is more about at which point you should start exercising your active skills. Of course sometimes the active skills are just not the goal - that’s also ok.