'Einstein here throws doubt, ' Alan commented, 'on whether Euclid's axioms, when applied to rigid bodies, hold. … He therefore sets out to test … the Galilei-Newtonian laws or axioms.' He had identified the crucial point, that Einstein doubted the axioms. Not for Alan the 'obvious duties', for nothing was obvious to him. His brother John, who by now regarded Alan with a rather patronising, but not hostile amusement, held that

艾伦看到了爱因斯坦最本质的东西，那就是他一直在怀疑。对爱因斯坦来说，没有什么「明确的义务」，一切都不是明确的。艾伦的哥哥约翰说：

You could take a safe bet that if you ventured on some self-evident proposition, as for example that the earth was round, Alan would produce a great deal of incontrovertible evidence to prove that it was almost certainly flat, ovular, or much the same shape as a Siamese cat which had been boiled for fifteen minutes at a temperature of one thousand degrees Centigrade.

你可以跟艾伦打赌，挑战一些明摆的道理。比如，你说地球是圆的，艾伦就偏要提出一堆证据，来证明它是平的，或者是胚珠形的，或者是在一千度的液体中煮了15分钟的暹罗猫形的。

Cartesian doubt came as an incomprehensible intrusion into Alan's family and school environment, an intrusion that the English coped with more by laughter than by persecution. But doubt being a very difficult and rare state of mind, it had taken the whole intellectual world a very long time to ask whether the 'Galilei-Newtonian laws or axioms', apparently 'self-evident', were actually true. Only by the late nineteenth century was it recognised that they were inconsistent with the known laws of electricity and magnetism. The implications were frightening, and it had needed Einstein to take the step of saying that the assumed basis of mechanics was actually incorrect, thereby creating the Special Theory of Relativity in 1905. This then proved inconsistent with Newton's laws of gravity, and to remove these contradictions Einstein had gone even further, casting doubt even on Euclid's axioms of space to create the General Theory of Relativity in 1915. The point of what Einstein had done did not lie in this or that experiment. It lay, as Alan saw, in the ability to doubt, to take ideas seriously, and to follow them to a logical if upsetting conclusion. 'Now he has got his axioms, ' wrote Alan, 'and is able to proceed with his logic, discarding the old ideas of time, space, etc.'

这种笛卡尔式的怀疑，对于艾伦的家庭和学校来说，是很难理解的，英国人往往对此嗤之以鼻。怀疑是一种很高难很诡异的思维状态，它长久地占据着知识界，比如说，人们怀疑「伽利略-牛顿定律」，而到了19世纪后期，人们确实发现了它不符合电磁定律。这种心理暗示很强大，它使爱因斯坦敢于说出，之前假设的力学基础是错误的，并在1905年提出了《狭义相对论》。紧接着，狭义相对论被证明与万有引力定律相悖，为了消除这个矛盾，爱因斯坦继续深入努力，甚至开始怀疑欧几里德空间，并在1915年提出《广义相对论》。爱因斯坦所做的，并不是根据实验，按艾伦的说法，他就是凭着怀疑，严肃地考查每一个问题，然后逼出一个符合逻辑的结论，哪怕这个结论让人难以接受。艾论说：「现在他有了自己的定理，这样才能符合他的逻辑，摒弃时间、空间等等旧的概念。」