刘老师前几天重温了爱老的科学发明论（http://blog.sciencenet.cn/blog-3377-882973.html），于我心有戚戚，借机补充几句。刘老师提到老爱的那篇演讲，我在前面的博文里也说过（http://blog.sciencenet.cn/blog-279992-873329.html）：

最能体现老爱思维路线的，大概是他1933年在牛津大学的Spencer演讲，即那篇著名的《理论物理学的方法》（On the Methodof Theoretical Physics）。他在那儿终于道出了自己的“经验论”：我们的经验令我们相信，自然是最简单的可能的数学思想的实现。（Our experience hitherto justifies us inbelieving that nature is the realization of the simplest conceivablemathematical ideas.）而演讲开头的一句话更有意思：对科学发现者来说，想象的产物是那么自然而然，几乎不该认为是思想的创造，而应看作本来的实在（To him who is a discoverer in this field, the products of his imagination appear so necessary and natural that he regards them, and would liketo have them regarded by others, not as creations of thought but as given realities）。在一定意义上，“我相信纯粹的思想能把握实在。”在老爱看来，想象约等于实在——这不仅把经验推得更远，也把自然拉得更近。这当然是康师傅的为自然立法的传统。

这篇Herbert Spencer演讲是1933年6月10日在牛津发表的，次年发表在《我的世界观》（MeinWeltbild, Amsterdam: Querida Verlag, 1934.）爱老在演讲中回顾了牛顿时代的自然哲学方法：从经验通过逻辑路线抽象出基本概念，而不是逻辑意义上的“人类思维的自由创造”：

The natural philosophers of those days were, on the contrary, most of them possessed with the idea that the fundamental concepts and postulates of physics were not in the logical sense free inventions of the human mind but could be deduced from experience by "abstraction" -- that is to say, by logical means.

   爱老认为，这个观点是错误的，但它的错到了广义相对论才显现出来（A clear recognition of the erroneousness of this notion really only came with tile general theory of relativity）。他发现，两个根本不同的原理都能与经验高度一致，这体现了原理的“虚构特征”（ficitious character）；它同时也证明了，想从基本事实逻辑演绎出力学的基本概念和假定的努力，是注定要失败的（this proves at the same time that every attempt at a logical deduction of the basic concepts and postulates of mechanics from elementary experiences is doomed to failure.）在《物理学与实在》（Physics and reality. The Journal of the Franklin Institute, Vol. 221, No.3. March,1936）中，爱老重申了他的自由发明论：Physics constitutesa logical system of thought which is in a state of evolution, whose basis cannot be distilled, as it were, from experience by an inductive method, but can only be arrived at by free invention.

Popper爵爷的“批判理性主义”，就是从老爱们的科学发明实践提出来的。他认为知识增长的模式就是“猜想-反驳”式的试错游戏，他在《猜想与反驳》中几乎重复了爱老的观点：scientific theories were not the digest of observations, but that they were inventions -- conjectures boldly put forward for trial, to be eliminated if they clashed with observations……他还追溯到柏拉图，“我们在柏老们那儿看到的正是有意识地构建和创造通向世界和世界知识的新方法”（What we find in Plato and his predecessors is the conscious construction and invention of a new approachtowards the world and towards knowledge of the world）。他认为牛顿的东西也只是天才的独特发明和猜想，而不是神圣的真理（Newton's theory is no more than a marvellous conjecture, an astonishingly good approximation; unique indeed,but not as divine truth, only as a unique invention of a human genius）；不是知识，而是信念（not epistēmē, but belonging to the realm of doxa）。

爵爷还浪漫地说，科学从神话开始，从神话的批判开始，而不是从收集观测数据开始，也不是从实验设计开始，而是从神话和魔术般的技术和实践的批判性讨论开始……（Thus science must begin with myths,and with the criticism of myths; neither with the collection of observations, nor with the invention of experiments, but with the critical discussion of myths, and of magical techniques and practices.）

没学过相对论和现代物理学的同学，也许不能真切感觉“自由创造”的作用和意义，毕竟大多数科学都在走着从经验到经验的现实主义和唯物主义的罗圈儿。没有自由发明和浪漫精神的科学，正如没有创意的艺术，只是没有流水和青草的荒漠。