A Philosophically Inexpensive Introduction to Twin-Earth

Frances, Bryan, A Philosophically Inexpensive Introduction to Twin-Earth.


孪生地球讨论这一个命题:Physical duplicates can have different thoughts. 张三及其复制品张3可以拥有不同的观念。【再通俗一些,即,张三及其克隆人张3,二人的物理身体一样,但是这并不意味着二人的观念一样。】【这种解读,是从身心关系的视角来看孪生地球】【孪生地球其实就是可能世界possible world的一种说法】

作者在该文分析了普特南的孪生地球的逻辑论证结构。并在最后提出六个问题并尝试解答。


在第二个问题中,作者提到了一些概念:

我们现代科学给我们的一个直觉是brain states fix or determine mental states.

依据这个直觉,我们有supervenience随附性:mental states supervene on brain states.

wide (or extrinsic) mental states:若除了我宇宙中没有其他东西,我将不会拥有这些状态。

narrow (or intrinsic) mental states:若宇宙中只有我,我仍然会拥有这些状态。

作者最后指出,反随附并不意味着外在。换言之,以下的推论是错误的:

(1)If anti-supervenient then wide; 或它的逻辑等价式:

(2)If narrow then supervenient


第三个问题中,作者指出以下两个逻辑关系是真的:

supervenient --> narrow  随附蕴涵内在

wide -->  non-supervenient  外在蕴涵非随附

反之则不成立。(即,不是充分必要条件)


第四个问题,作者指出,

Anti-individualism focuses on supervenience: it says that beliefs are anti-supervenient. Externalism is a different claim: it says beliefs are wide. 反个体主义关心随附性;外在主义关心外在性。


AI:

The article "A Philosophically Inexpensive Introduction to Twin-Earth" by Bryan Frances presents a variant of the Twin-Earth thought experiment, designed to address key debates in philosophy of language and mind, particularly focusing on externalism and anti-individualism. The essay explores how meanings and beliefs can differ across possible worlds despite physical identity. It uses the example of two similar fish species, "walleye" and "sauger," to illustrate how word meanings and beliefs can shift when the meanings of these words are switched in an imaginary world.


Key takeaways include:


1. **Linguistic Anti-Individualism**: This argues that the meanings of words aren't determined solely by what's in our heads but also by external factors. Bryan can be physically identical in two worlds but still express different meanings due to these external factors.


2. **Mental Anti-Individualism**: Bryan can have different beliefs in two worlds while being physically identical. This shows that beliefs aren't solely determined by internal, physical states.


The article continues with technical discussions on **narrow content** (thoughts that are internal and don’t depend on the external environment), concepts of **intensions and extensions**, and an analysis of Putnam's famous Twin-Earth argument about how content isn't just "in the head."


### The Last Section's Questions and Answers:


1. **Extensions and Intensions**: Extensions refer to the things a word applies to, while intensions are the meanings behind those words. The debate arises when considering whether intensions always determine extensions and vice versa. In some cases, different intensions (like "creature with a heart" vs. "creature with a kidney") may pick out the same extensions (the same set of animals).


2. **Narrow, Wide, and Supervenient States**: Narrow states are mental states that do not depend on the external world, while wide states do. Supervenience refers to mental states being determined by physical states. The text explores how narrow and wide states relate to supervenience, showing that narrow states might not always supervene on physical states.


3. **Externalism vs. Anti-Individualism**: Externalism posits that the content of beliefs is influenced by external factors, not just what's inside a person’s mind. Anti-individualism suggests that even if two people are physically identical, their beliefs can differ due to their external environments.


4. **Is Meaning in the Head?**: A significant question raised is whether meaning is purely a mental phenomenon or whether external factors play a crucial role in determining meaning. Externalism argues that meanings are not just "in the head" but are also shaped by external contexts and the way words are used in the world.


The answers aim to clarify these complex philosophical concepts while showing how they relate to the original Twin-Earth experiment and contemporary debates.


这篇文章《双地球的哲学性廉价入门》由Bryan Frances撰写,讨论了双地球的思想实验,主要围绕语言哲学和心灵哲学的外部主义(externalism)和反个体主义(anti-individualism)展开。通过鱼类“walleye”和“sauger”两个相似物种的例子,作者展示了即使在物理上相同的情况下,词汇的意义和信念也可能在不同的世界中发生变化。这篇文章试图证明以下两个论点:

1. **语言反个体主义**:词汇的意义不仅仅由我们大脑中的内容决定,还受到外部环境的影响。即使Bryan在两个世界中物理上完全相同,但由于外部因素的不同,他所表达的意义也有所不同。

2. **心灵反个体主义**:尽管Bryan在两个世界中的物理状态完全一致,但他在两个世界中的信念是不同的。这表明信念不仅仅由个体的物理状态决定,还受外部世界的影响。

文章随后讨论了**狭义内容**(narrow content)——即那些不依赖外部环境的内部思维内容,以及词汇的**内涵(intension)和外延(extension)**,并分析了Putnam的著名双地球论证,探讨了内容如何不仅仅“存在于头脑中”。

### 最后部分的问题和解答:

1. **内涵与外延**:外延指的是词汇所指向的事物集合,而内涵是词汇背后的意义。问题在于内涵是否总是决定外延,反之亦然。举例来说,“有心脏的生物”和“有肾脏的生物”虽然内涵不同,但它们的外延(即它们所指的动物集合)可能是相同的。

2. **狭义、广义与伴随性**:狭义状态是指那些不依赖外部世界的心理状态,而广义状态则依赖于外部环境。伴随性(supervenience)指的是心理状态由物理状态决定的问题。文中讨论了狭义和广义状态与伴随性的关系,指出狭义状态可能并不总是伴随于物理状态。

3. **外部主义与反个体主义的区别**:外部主义认为,信念的内容不仅受内心状态的影响,还受到外部环境的影响。反个体主义则指出,即便两个人在物理上完全一致,由于外部环境的不同,他们的信念内容可能不同。

4. **意义是否只在头脑中?**:文章探讨了意义是否完全是精神现象,还是也受到外部世界的影响。外部主义者认为,意义不仅仅是“在头脑中”的内容,还受外部环境和词汇在世界中使用方式的影响。

这些问题和解答帮助澄清了文章中的复杂哲学概念,并将其与双地球思想实验及当代哲学讨论联系起来。