2.1.6 “是”与“不是”引起的歧义

在四种日常判断（命题）表述中，关于肯定和否定分别使用了“是”和“不是”这两个词。如果对这两个词进一步深入思考，会发现这两个词在日常生活中使用的比较宽泛，很容易引起歧义。

“是”这个日常使用的词汇如果用数学符号来表示应该用“=”符号。如果按照这样的规则去使用“是”这个词汇，那么除了在数学表达和一些抽象形式的逻辑表达语句之外，“是”这个词汇，基本上无用武之地（这是因为，在物质或现实世界中，没有两样事物是完全一样的）。在很多日常数情况下，“是”这一概念严格来讲应该为“属于”这个概念。

比如：
创业板股票是在深圳证券交易所公开交易的股票。
这句话严格来说应该表述为“创业板股票属于在深圳证券交易所公开交易的股票”。

当用“是”这一词汇，连接两个不同概念时，请阅读者时刻谨记，没有任何两个事物是完全一样的。

还有一种情况，那就是随着时间的推移即使同一个概念在历史的不同时间点也不能用“=”将二者联系起来。请交易者回顾本系列“1.1.5.2 股票指数样本股的变化与失真”文章提到的道琼斯工业指数那张图：

关于“不是”这一概念，同样去深究的话，日常使用中其背后的含义大多也是“不属于”这样一个概念。“不是”一词不像“是”那样容易歧义，因为当不属于概念成立的时候，不是同样也就成立了。只是大家在日常语言中不深究自己真正的表达意图罢了。

例如：
有些蓝筹股不是沪深300指数指标股。
实际其真实的意思是“有些蓝筹股不属于沪深300指数指标股”。

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2.1.5 Comparison of four judgments (propositions)

In the above picture, the two forms of universal and particular of the concept of NASDAQ stock are used, and then four sentences are formed for their affirmation and negation. Give each sentence a picture for understanding.

Among these four propositions, some propositions can be derived from each other to derive another proposition. See the table below for details.

Proposition type	Other proposition types that can be derived	Example
A	E	NASDAQ stocks are publicly traded stocks in the United States. Some publicly traded stocks in the United States are NASDAQ stocks.
I	I	Some NASDAQ stocks are index stocks of the Nasdaq 100 Index. Some index stocks of the Nasdaq 100 Index are NASDAQ stocks. （Although this sentence does not meet the usual language habits, it is still established.）
E	E	NASDAQ stocks are not publicly traded stocks in the NYSE. Publicly traded stocks in the NYSE are not NASDAQ stocks.

It should be noted that O propositions cannot derive O propositions. For example, the following two sets of sentences are compared.

The first set of sentences is as follows:

• Some NASDAQ100 index stocks are not blue chips. (Original O proposition)
• Some blue chips are not NASDAQ100 index stocks. (The derived O proposition is established)

The second set of sentences:

• Some NASDAQ stocks are not index stocks of the NASDAQ100 index. (Original O proposition)
• Some NASDAQ100 index stocks are not NASDAQ stocks. (The derived O proposition cannot be established)

It can be seen from the second set of sentences that the O proposition cannot derive the O proposition.

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2.1.5 四种判断（命题）对比

在上述图形中使用了“创业板股票”这个概念的全称和特称，然后对其肯定和否定组成了四个句子，并赋予了可供理解的图形。

在这四组命题当中，有些命题之间可以相互推导得出另一个命题，请看下表。

命题类型	可推导出的其他命题类型	例句
A	E	创业板股票 是 在深圳证券交易所公开交易的股票。 有些在深圳证券交易所公开交易的股票 是 创业板股票。
I	I	有些创业板股票 是 创业板50指数指标股。 有些创业板50指数指标股 是 创业板股票。（此句虽不符合平时语言习惯，但还是成立的。）
E	E	创业板股票 不是 在上海证券交易所公开交易的股票。 在上海证券交易所公开交易的股票 不是 创业板股票。

这里需要注意的是O命题不能推导出O命题。例如下面两组句子对比。

第一组句子如下：

有些沪深300指数指标股不是蓝筹股。（原O命题）

有些蓝筹股不是沪深300指数指标股。（推导出的O命题成立）

这两句看起来问题不大，好像可以O命题可以推导出O命题。

第二组句子：

有些创业板股票不是创业板50指数指标股。（原O命题）

有些创业板50指数指标股不是创业板股票。（推导出的O命题不能成立）

从第二组句子当中可以看出O命题是无法推导出O命题的。

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2.1.4 O-type: Particular and negative

In the O-type statement, the subject is "partial" and the predicate is "negative". For example, the following sentence:

Some flower color is not purple.
Some birds are not migratory birds.
Some first middle school teachers are not excellent teachers.
Some stocks traded in the New York Stock Exchange are not S&P 500 index stocks.

The O-type statement and the E-type statement have little difference in the impression people have on everyday use. Therefore, O-type statements are rarely used by authors to avoid doubts about the author's ability.

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2.1.4 特称否定

特称肯定语句中，主词是“部分”，述词是“否定”。例如下面的句子：

有些花的颜色不是紫色。
有些鸟不是候鸟。
有些第一中学教师不是优秀教师。
有些交易代码以1开头的交易品种不是国债逆回购品种。

特称否定的语句和特称肯定的语句在日常使用中对人们产生的印象差别不大。因此特称否定的语句就类似于特称肯定的句子那样，作者也很少这么使用，以免听者或阅读者产生对作者能力的怀疑。

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Quote 4 --To doubt

In order to seek truth, it is necessary once in the course of our life, to doubt, as far as possible, of all things.

--"Principles of Philosophy"  , René Descartes

2.1.3 E-type of propositions: Universal and negative

E-type refers to the two concepts in the establishment of "no" logical relationship, the coverage of the previous concept is all, the coverage of the latter concept is all.

A is not C.

A:all, C:all.

For example, the following sentence:

Pine trees are not broad-leaved trees.
White horse is not a dark horse.
Zhang San is not a good person.
Indicator stocks are not stocks that have just been listed.

The tone of E-type also has a firm attitude, but the e-type statement rarely leaves a guiding role for action for people's actions.

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