But the basis of Freud's ideas aren't accepted by all philosophers, though many accept that he was right about the possibility of unconscious thought. Some have claimed that Freud's theories are unscientific. Most famously, Karl Popper (whose ideas are more fully discussed in Chapter 36) described many of the ideas of psychoanalysis as 'unfalsifiable'. This wasn't a compliment, but a criticism. For Popper, the essence of scientific research was that it could be tested; that is, there could be some possible observation that would show that it was false. In Popper's example, the actions of a man who pushed a child into a river, and a man who dived in to save a drowning child were, like all human behaviour, equally open to Freudian explanation. Whether someone tried to drown or save a child, Freud's theory could explain it. He would probably say that the first man was repressing some aspect of his Oedipal conflict, and that led to his violent behaviour, whereas the second man had 'sublimated' his unconscious desires, that is, managed to steer them into socially useful actions. If every possible observation is taken as further evidence that the theory is true, whatever that observation is, and no imaginable evidence could show that it was false, Popper believed, the theory couldn't be scientific at all. Freud, on the other hand, might have argued that Popper had some kind of repressed desire that made him so aggressive towards psychoanalysis. Bertrand