Today I want to spend--The title of today’s lecture is The Universal Principle of Risk Management. Pooling and the Hedging of Risk. 今天我想„今天这堂课的主题是风险管理的普遍原则，风险汇聚和风险对冲 What I’m really referming to is what I think is the very original the deep concept that underlies theoretical finance 今天我要教授的知识，我认为是金融理论中最基本最核心的概念 I wanted to get that first. 我想先说说这个 It really is probability theory and the idea of spreading risk through risk pooling. 就是概率论，以及通过风险汇聚来分摊风险 So, this idea is an intellectual construct that appeared at a certain point in history and it has had an amazing number of applications and finance is one of these. 这一极具智慧的概念，诞生于某一特定历史时期，并且应用广泛，金融是其一 Some of you -- 对于部分人来说 This incidentally will be a more technical of my lectures and it’s a little bit unfortunate that it comes early in the semester. 这堂课相对于我其他的课程较为专业，而且不巧的是，这门课在学期伊始就开始了 For those of you who have had a course in probability and statistics, there will be nothing new here. Well, nothing in terms of the math. 对于已经学过概率和统计的同学来说，这堂课就没什么新鲜的了，当然，那是从数学角度来说的 The probability theory is new, Others though, I want to tell you that it doesn’t 但概率论是个新知识，其他的，我想告诉你们不必 If you’re shopping 如果你还在挑选课程 I had a student come by yesterday and ask he’s a little rusty in his math skills, if he should take this course. 昨天有个学生来问我，他的数学有点荒废了，他该不该选这门课 I said ,“Well if you can understand tomorrow’s lecture” that’s today’s lecture, then you should have no problem. 我说，如果你能听懂明天的课，也就是今天这课，那你不会有问题的。 I want to start with the concept of probability. Do you know what a probability is? 我想从概率的概念开始讲起，你们知道什么是概率吗 We attach a probability to an event.OK? 我们举个实例吧，好吗 What is the probability that the stock market will go up this year? 今年的股票市场会走高的概率是多少 I would say-- my personal probability is .45. 我会说，我个人猜想的概率是0.45 That’s because I’m a bear but 那是因为我对股市持悲观的态度，但 Do you know what means? 你们知道那是什么意思吗？ That 45 times out of 100 the stock market will go up and the other 55 times out of 100 it will stay the same or go down. That’s a probability. 就是，股票市场会走高的可能性是45%，剩下的55%市场会走平或者走低，那就是概率 Now, you’re familliar with that concept, right? 现在，你们觉得这个概念似曾相识了吧 If someone says the probability is .55 or .45. Well you know what that means. 如果有人提到概率是0.55或者0.45，你就知道他说的是什么意思了 I want to emphasize that it hasn’t always been that way and that probability is really a concept that arose in the 1600s. 我想说，概率的表述并非一贯如此，这个概念成型于十七世纪 Before that, nobody ever said that. Ian Hacking, who wrote a history of probability theory searched through world literature for any reference to a probability and could find none anywhere before 1600. 那时，概率被第一次提出，伊恩.哈金为概率论追根溯源，他查遍世界所有关于概率的文献，发现无法追溯到十七世纪以前 There was an intellectual leap that occurred in the seventeenth century and it became very fashionable to talk in terms of probabilities. 也就是说，十七世纪中诞生了一次智慧的飞跃，用概率来表述成了件很时髦的事 It spread throughout the world-- the idea of quoting probabilities. 引用概率的这种表述方式很快传遍世界 But it was --It’s funny that shch a simple idea hadn’t been used before. 但这„很有意思的是如此简单的方式此前从未被使用过 Hacking points out that the word probability--or probable was already in the English language. 哈金指出概率这个词，或者说可能已经存在于英语中 In fact, Shakespeare used it, but what do you think it meant? 事实上，莎士比亚用过，但你知道它代表什么吗 He gives an example of a young woman, who was describing a man that she liked, and she said, I like him very much, I find him very probable. 他举了一个年轻小姐的例子，一位小姐描述她喜欢的男子，她说道，我太喜欢他了，我觉得他有很大可能 What do you think she means? Can someone answer that? 你们觉得她是什么意思，有人能回答吗 Does anyone know Elizabettan English well enough to tell me? What is a probable young man? 有擅长近代英语的同学能回答我吗，什么是一个“很可能”的年轻男子 I’m asking for an answer, It sounds like people have no idea.Can anyone venture a guess? No one wants to venture a guess? 我在征求回答，好像没人知道，有人敢猜一下吗，没人想试试吗 Maybe father a children? That he can father children? I don’t think that’s what she meant but maybe. 是不是说他生殖能力旺盛，你是说他“精”力旺盛吗，我想她不是那个意思，但也有可能 No, what apparently she meant is trustworthy, That’s very important quality in a person I suppose. 不是的，她的意思显然是“值得信赖”，我想那是为人的重要品质 So, if something is probable you mean that you can trust it and so probability means trustworthiness. 所以，如果有什么是很可能的，说的是你可以信赖它，也就是说，这里的可能性等于可信赖度 You can see how they moved from that definition of probability to the current definition. 所以你可以清楚地了解到，概率是如何由那个定义转变为今天的定义的。 But Ian Hacking, being a good historian,thought that someone must have had some concept of probability going before even if they didn’t quote it as a number the way, it must have been in their head or in their idea. 但是这位优秀的历史学家伊恩.哈金认为，一定有人在更早时候就用过概率这个概念，即便他们没有用数字来表述，但他们一定有过类似的想法 He searched through world literature to try to find some use of the term that preceded the 1600s and he concluded that there were probably a number of people who had the idea, but they didn’t publish it and it never became part of the established literature, partly because, he said, throughout human history, there has been a love of gambling and probability theory is extremely useful if you are a gambler. 他遍览全球文献试图寻找这个词在十七世纪前的使用证据，并且总结说，很可能有许多人有过相同的想法，但没有公开阐述过，并且从未成文发表过，他说，部分原因是，纵观人类历史，赌博曾风靡一时，而概率论对于一个赌徒来说是大有裨益的 Hacking believes that there 本文来源：https://www.wddqw.com/doc/1ec3c9ddb9d528ea81c779e4.html