# 师徒对话 - “命题”和“问题” （2015/12）

1，习题：赫拉克勒斯（Hercule）向斯芬克司（Sphinx）问路

2，解答

1）定义二个原子命题：

p1: “正义之路在右边；

p2: 斯芬克司说真话。

2）建立真值表

———————————

p1      p2      A      B

0        0       1      0

0        1       0      0

1        0       0      1

1        1       1      1

———————————

A = p1<->p2

B = (p1<->p2)<->p2

A是斯芬克司的回答，当赫拉克勒斯问：正义之路在右边吗？

B是斯芬克司的回答，当赫拉克勒斯问：正义之路在右边当且仅当你说真话吗？

The proposition is a picture of reality.

The proposition is a model of the reality as we think it is.

The proposition shows its sense.

The proposition shows how things stand, if it is true. And it says, that they do so stand.

The proposition determines reality to this extent, that one only needs to say “Yes” or “No” to it to make it agree with reality.

It must therefore be completely described by the proposition. A proposition is the description of a fact.

As the description of an object describes it by its external properties so propositions describe reality by its internal properties.

The proposition constructs a world with the help of a logical scaffolding, and therefore one can actually see in the proposition all the logical features possessed by reality if it is true. One can draw conclusions from a false proposition.

To understand a proposition means to know what is the case, if it is true.

，。。。

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