What exactly is meant by the word "risk"? The word is certainly used frequently in everyday conversation and seems to be well understood by those using it. To most people, risk implies some form of uncertainty about an outcome in a given situation. An event might occur and, if it does, the outcome is not favourable to us; it is not an outcome we look forward to. The word "risk" implies both doubt about the future, and the fact that the outcome could leave us in a worse position than we are in at the moment. Writers, particularly in America, have produced a number of definitions of "risk". Risk is the possibility of an unfortunate occurrence. Risk is a combination of hazards. Risk is unpredictability -- the tendency that actual results may differ from predicted results. Risk is uncertainty of loss. Risk is the possibility of loss. Looking at the definitions there does seem to emerge some kind of common-thread running through each of them. Firstly, there is an underlying idea of uncertainty, what we have referred to as doubt about the future. Secondly, there is the implication that there are different levels or degrees of risk. Thirdly, there is the idea of a result having been brought about by one cause or causes.
　　If a child is playing in the middle of a busy road; if a workman is using a machine while he is unaware, that it is faulty and dangerous; if the pedestrians are unaware that a wall running alongside a pavement is a dangerous condition and about to collapse, what will happen to them? There is an element of risk and uncertainty in each of these situations. The child may escape free of injury, the machine may hold out until the workman has finished using it and the wall may not collapse and injure passersby. Alternatively, there could be serious injury in each case. Uncertainty can exist in the abstract, it is not dependent on being recognized as existing by those who may be most directly involved. Uncertainty is linked more to the event itself, rather than to any personal perception of the existence of uncertainty.
　　“风险”这个词的真正含义是什么?这个词在我们的日常会话中经常出现，它似乎被人们所理解。
　　对大多数人来说，风险指的是，在特定情况下某种结果的不确定性形式。某种事件可能会发生，如果发生，其结果对我们不利。它不是我们期望的结果。“风险”既包含着对未来的疑虑，又包含着发生的结果将使我们处于比现在更糟的境地。
　　许多学者，特别是美国的学者，他们对风险的概念下了一些定义：
　　风险是不幸事故发生的可能性。
　　风险是——切危险的综合体。
　　风险是一种无法预测的，其趋势是，实际后果可能不同于预测后果。
　　风险是损失的不确定性。
　　风险是损失的可能性。
　　综合以上定义，有一种共同的思路贯穿于每个定义之中，那就是我们已经提到过的对未来的疑虑。第二，定义意味着风险存在不同的水准和不同级别。第三，定义包含这样—个思想，即风险是由于某个原因或某些原因带来的一种结果。
　　如果一个小孩在繁华的道路中玩耍；如果一个工人正在使用机器而不知道机器有毛病或有危险；如果过往的行人不知道人行道旁的围墙处于危险状态并要倒塌，那么将会发生什么情况?每种情况都有风险和不确定性的因素，小孩有可能逃避伤害，机器有可能不会发生意外，围墙可能没有伤害过往行人。与此相反，也许每种情况都可能发生严重的伤亡事故。不确定性存在于抽象之中，它不依赖于那些有直接联系的人是否承认它的存在，与不确定性联系的主要是事件本身，而不是人们对不确定性存在的认识。