大拇指规则 (RULE OF THUMB)

大拇指规则 (RULE OF THUMB) 可以理解诚是一种试探法 (heuristics)
试探法 (heuristics)：The high-level, often imprecise rules of thumb and intuitive reasoning that experts use to solve problems.
专家用于求解问题的高级的但常常是不确切的经验法则和直觉推理法。
大拇指规则字面的理解应该是从经验阿实践中总结得出的方法和规则什么的，不是经过科学实验得出的， 因为老早以前没有温度计，别人烧水啊什么的时候呢就没得知道到底有多热了，所以呢就用大拇指浸一下，大叫一声烫啊，然后就可以知道，哇,水已经很热了。还有一种说法呢，就比较正常一点人性化一点了，因为古代的时候大家都是用便于计量的单位来计量的，比方说脚阿手指头阿什么的，忘记掉以前哪个英国国王说滴，诺，从我鼻子到我伸出的手指头就是一yard.

大拇指法则=经验法则一种可用于许多情况的有用的原则，但并不是放诸四海皆准
在英国普通法中， 有一条“大拇指规则”（rule of thumb）， 意即只要用一根比大拇指小的棍子鞭打妻子，便不属虐待妻子行.
为。后经引申在管理学等其他知识领域上理解为经验和试探法.

大拇指规则的英文解释:
"rule of thumb"
by Mark Israel

[This is a fast-access FAQ excerpt.]

This term for "a simple principle having wide application but not
intended to be strictly accurate" dates from 1692. A frequently
repeated story is that "rule of thumb" comes from an old law
regulating wife-beating: "if a stick were used, it should not be
thicker than a man's thumb." Jesse Sheidlower writes at
[...]

[The URL that was given above is no longer valid. Jesse's
article on "rule of thumb" is now at
<http://www.randomhouse.com/wotd/index.pperl?date=19961108>.]

"It seems that in 1782 a well-respected English judge named Francis
Buller made a public statement that a man had the right to beat his
wife as long as the stick was no thicker than his thumb. There was
a public outcry, with satirical cartoons in newspapers, and the
story still appeared in biographies of Buller written almost a
century later. Several legal rulings and books in the late
eighteenth and nineteenth centuries mention the practice as
something some people believe is true. There are also earlier
precedents for the supposed right of a man to beat his wife.

"This 'rule' is probably not related to the phrase 'rule of
thumb', however. For one thing, the phrase is [...] attested
[earlier ...]. (Of course, it's possible that it was a well-known,
but unrecorded, practice before Buller.) Another problem is that
the phrase 'rule of thumb' is never found in connection with the
beating practice until the 1970s. Finally, there is no semantic
link [... from what was presumably a very specific distinction to
the current sense 'rough guideline']. The precise origin of 'rule
of thumb' is not certain, but it seems likely to refer to the thumb
as a rough measuring device ('rule' meaning 'ruler' rather than
'regulation'), which is a common practice. The linkage of the
phrase to the wife-beating rule appears to be based on a
misinterpretation of a 1976 National Organization of Women report,
which mentioned the phrase and the practice but did not imply a
connection. There is more information about this, with citations
from relevant sources, at the Urban Legends Archive."

Thumbs were used to measure *lots* of things (the first joint
was roughly one inch long before we started growing bigger, and
French pouce means both "inch" and "thumb"). The phrase may also
come from ancient brewmasters' dipping their thumb in the brew to
test the temperature of a batch; or from a guideline for tailors:
"Twice around the thumb is once around the wrist..."

For a definitive rule of thumb, see the paper "Thumb's rule
tested: Visual angle of thumb's width is about 2 deg." by Robert P.
O'Shea in Perception, 20, 1991, pp. 415-418.