Nor will it suffice in reply to point to the fact that the sciences continually assume the truth of the premisses they argue from. For though this is often a convenient assumption for the purpose in hand, it is one thing to assume the truth of premisses for the purposes of an inquiry, and quite another to assume it absolutely. For in the former case our assumption may be, and should be, accompanied by a consciousness that upon another and fitting occasion the premisses now assumed to be true may themselves be inquired into: to regard them, therefore, as absolute is to misinterpret their logical condition. There are no good reasons, then, why the sciences should surrender to the arbitrary demands of the traditional logic, and sacrifice their practices which have been sanctified by the successes of 2,000 years to theories which sprang from a misunderstanding of scientific procedure, and have since lost all contact with it. The original mistake was pardonable, but it ought not to be regarded as an insult to logic to require it to understand the procedure by which the sciences actually progress. § 29. The scientist then should not be terrified by the charge that his ‘truths’ are ‘only probable’. For it is better to be satisfied with probabilities than to demand impossibilities and starve. Moreover, a high degree of probability means ‘practical certainty’, i.e. confidence enough to move to action. Such certainty so convinces and satisfies the mind that it cannot feel more certain about anything; the logical gap between it and absolute certainty is psychologically negligible. We are sacrificing, therefore, nothing but a superstition, nothing that has any value for us, by renouncing the demand for absolute truth and demonstrative ‘proof’, and we gain in return a charter of liberty. For to admit the essential progressiveness of scientific truth and its indefinite capacity for improvement means unlimited freedom to research into truths which are infinitely perfectible, because they are never ‘absolute’. The ideal of the infinite perfectibility of truth, and the infinite progressiveness of science, is more than an adequate substitute for the ‘logical ideal’ which is abandoned. For not only is it an ideal which works, but it really embodies a nobler aspiration than that which represented science as ‘resting’ in absolute perfection on fixed ‘foundations’ of ‘eternal’ truth. The sentiment which inspires this group of metaphors is given away by the word ‘rest’. A science that desires to _rest_ is one that is unwilling to _move_ and unable to _advance_. Fixed ‘foundations’ are needed only for standing firm and standing still, and it turns out that what is strictly meant by ‘eternal’ is not that truths last for ever, but that they are not related to ‘time’ at all, and so have really no application to ‘events’.[400]