"... Is this world real? This is a venerable philosophical issue and I do not wish to be embroiled in the finely honed squabbles to which it has led. I merely state my own working hypothesis: that there is indeed an outside world, and that it is largely independent of our observing it. We can never fully know this outside world, but we can obtain approximate information about some aspects of its properties by using our senses and the operations of our brains. Nor, as we shall see, are we aware of everything that goes on in our brains, but only of some aspects of that activity. Moreover, both these processes—our interpretations of the nature of the outside world and of our own introspections—are open to error. We may think we know our motives for a particular action, but it is easy to show that, in some cases at least, we are in fact deceiving ourselves."