Earlier quoted context omitted.
> Security is always reactionary, you can't defend against an attack you've never seen before Yes you can, that's part of the appeal of applying machine learning to security. They don't rely on things like signatures or existing heuristics to identify things as malicious.
If you train your security on parallel lines, and I come in with circles, I've just defeated your security. Machine learning only learns how to categorize things into predetermined categories. If I come in with a novel category it's never seen before, the best it can do is guess, and most likely, it will be worse at guessing than random chance.
> Machine learning only learns how to categorize things into predetermined categories.
This is just one type of machine learning called classification, there are others like regression and clustering which can be combined to create more robust models. Look at the technology behind Cylance's product which identifies files as malicious or not pre-execution. They are not just using classification.