'Brain in a vat' Thought Experiment

"Since the brain in a vat gives and receives the exact same impulses as it would if it were in a skull, and since these are its only way of interacting with its environment, then it is not possible to tell, from the perspective of that brain, whether it is in a skull or a vat. Yet in the first case most of the person's beliefs may be true (if he believes, say, that he is walking down the street, or eating ice-cream); in the latter case they are false. Since, the argument says, you cannot know whether you are a brain in a vat, then you cannot know whether most of your beliefs might be completely false. Since, in principle, it is impossible to rule out your being a brain in a vat, you cannot have good grounds for believing any of the things you believe; you certainly cannot know them."


Now If you'll please exscuse me the mad scientist is draining and replacing my suspension fluid..