 The general picture of Popper’s philosophy of science, then is this: Hume’s philosophy demonstrates that there is a contradiction implicit in traditional empiricism, which holds that universal scientific laws are in some way finally confirmable by experience, despite the open-ended nature of the latter being acknowledged. Popper eliminates the contradiction by removing the demand for empirical verification in favour of empirical falsification or corroboration. Scientific theories, for him, are not inductively inferred from experience, nor is scientific experimentation carried out with a view to verifying or finally establishing the truth of theories; rather, all knowledge is provisional, conjectural, hypothetical—the universal theories of science can never be conclusively established. Hence Popper’s emphasis on the importance of the critical spirit to science—for him critical thinking is the very essence of rationality. For it is only by critical thought that we can eliminate false theories and determine which of the remaining theories is the best available one, in the sense of possessing the highest level of explanatory force and predictive power.