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Meet Lucy. She was a math major in college, and aced all her courses in probability and statistics.
认识一下露西。她在大学主修数学，并且在所有的概率与统计课程中获得了高分。
Which do you think is more likely: that Lucy is a portrait artist, or that Lucy is a portrait artist who also plays poker?
你觉得哪一个情况可能性更高：露西是一个肖像画家，或露西不仅是一个肖像画家，同时也是扑克玩家？
In studies of similar questions, up to 80 percent of participants chose the equivalent of the second statement: that Lucy is a portrait artist who also plays poker.
在一个提出相似问题的研究中，高达80%的参与者选择了与第二个陈述等价的情况：即露西是一个肖像画家，而且也是一个扑克玩家。
After all, nothing we know about Lucy suggests an affinity for art, but statistics and probability are useful in poker.
毕竟，我们所知的露西和艺术没有什么联系，但在扑克中，概率与统计却很有用。
And yet, this is the wrong answer. Look at the options again.
不过，这是一个错误的猜测。再次看一下两个选择的陈述。
How do we know the first statement is more likely to be true? Because it's a less specific version of the second statement.
我们是如何知道第一个陈述更可能是真的呢？因为相比第二个陈述，它是细节较少的版本。
Saying that Lucy is a portrait artist doesn't make any claims about what else she might or might not do.
说露西是一个肖像画家不代表她可能做，或可能不做其它事情。
But even though it's far easier to imagine her playing poker than making art based on the background information,
基于背景信息，尽管想象露西玩扑克比想象她从事艺术工作简单得多，
the second statement is only true if she does both of these things.
但只有在她同时做这两件事时第二个陈述才可为真。
However counterintuitive it seems to imagine Lucy as an artist, the second scenario adds another condition on top of that, making it less likely.
不论想象露西是一个艺术家看起来有多违背直觉，第二个情景中额外增加的一个条件使其可能性变低。
For any possible set of events, the likelihood of A occurring will always be greater than the likelihood of A and B both occurring.
对于任何可能的事件集，事件A可能发生的概率总是比事件A和事件B同时发生的概率高。
If we took a random sample of a million people who majored in math, the subset who are portrait artists might be relatively small.
如果我们随机抽取100万个数学专业的人，其中是肖像画家的子集可能相对较小。
But it will necessarily be bigger than the subset who are portrait artists and play poker.
但是这必定会大于同时拥有肖像画家和扑克玩家双重身份的子集。
Anyone who belongs to the second group will also belong to the first -- but not vice versa.
任何属于第二个子集的人，也同时属于第一个子集。反之，却并非如此。
The more conditions there are, the less likely an event becomes.
条件越多，一个事件发生的可能性越低。
So why do statements with more conditions sometimes seem more believable?
所以，为什么包含更多条件的陈述有时更加令人信服？
This is a phenomenon known as the conjunction fallacy.
这是一个称为“合取谬误”的现象。
When we're asked to make quick decisions, we tend to look for shortcuts.
当我们被要求快速地做出选择，我们通常偏向于选择捷径。
In this case, we look for what seems plausible rather than what is statistically most probable.
在这种情况下，我们会选择看似更具可行性的选项，而非从统计意义上讲最有可能的选项。
On its own, Lucy being an artist doesn't match the expectations formed by the preceding information.
就其本身而言，露西是艺术家这一事件并不符合信息处理所生成的预期。
The additional detail about her playing poker gives us a narrative that resonates with our intuitions -- it makes it seem more plausible.
额外的一个关于她玩扑克的细节提供了与我们直觉相吻合的叙述--这细节使之看似更加可信。
And we choose the option that seems more representative of the overall picture, regardless of its actual probability.
于是，不论选项的实际概率，我们选择了看似更加具有整体代表性的选项。
This effect has been observed across multiple studies, including ones with participants who understood statistics well
在许多研究中，都观察到了这一现象，包括那些熟知统计知识的研究参与者，
from students betting on sequences of dice rolls, to foreign policy experts predicting the likelihood of a diplomatic crisis.
从学生们对骰子掷出顺序的赌注，到外交政策专家对外交危机可能性的预测。
The conjunction fallacy isn't just a problem in hypothetical situations.
合取谬误不是一个仅存在于假设情况下的问题。
Conspiracy theories and false news stories often rely on a version of the conjunction fallacy to seem credible
阴谋论和虚假新闻通常仗着一个合取谬误的版本，使之看似看信，
the more resonant details are added to an outlandish story, the more plausible it begins to seem.
在一个奇特故事中加入越是与我们直觉相互呼应的细节，会使这个故事看起来更加真实。
But ultimately, the likelihood a story is true can never be greater than the probability that its least likely component is true.
但最终，一个故事为真的可能性永远不会超过事实真相最小的可能性。
