Putnam on the Meaning of 'Meaning'

Philosophy of Mind
Curtis Brown

Background

Several pairs of terms which make more or less the same distinction:

The extension of a term is the set of things of which it is true. So the extension of the term 'rabbit' is the set of all the rabbits in the world; the extension of 'blue' is the set of all the blue things; the extension of 'pets in Curtis Brown's household' is {Callie, Elsa}, and so on.

Obviously the extension of a term used by someone depends not just on that person's intrinsic properties, but also on his or her environment or context. (My wife could have acquired another pet today, in which case 'pets in Curtis Brown's household' now has an additional item in its extension.)

There has to be more to meaning than extension. Two expressions can have the same extension and yet differ in meaning: 'the Morning Star' and 'the Evening Star' both refer to Venus, but don't mean the same thing; similarly, 'number of sides of a triangle' and 'number of angles of a triangle' have the same extension (namely, the number three), but don't mean the same thing.

Intensions are often thought of as having two properties: (1) intensions determine extensions: the intension of a word or phrase is thought to determine which things it is true of. (2) grasping an intension, understanding the meaning of an expression, is a narrow psychological state.

What kind of thing could an intension be, if it were to satisfy these two conditions? One common idea is to think of an intension as being something like a set of necessary and sufficient conditions for being in the extension of an expression. So the intension of "triangle" might be something like: three-sided, closed, planar figure. Having three sides, being closed, being planar, and being a figure are all necessary conditions for being a triangle; and the conjunction of all of these necessary conditions gives us a sufficient condition for being a triangle. Similarly, the intension of "bachelor" might be something like: adult, unmarried male. Being an adult, being unmarried, and being male are all necessary conditions for being a bachelor, and their conjunction is a sufficient condition.

Putnam's Negative Thesis

The picture above can't be correct, according to Putnam. Narrow psychological state doesn't determine extension; therefore, at least one of the two links must be broken.

This thesis is negative, and is supported by examples that appear to show that two exact duplicates could refer to different things. (Thus when Oscar uses the word 'water', he refers to H2O; but when his exact duplicate Twin Oscar uses the word in his language that sounds just like 'water', he refers to XYZ.)

Putnam's Positive Theses

Putnam offers two reasons for the failure of psychological state to determine reference.

1. The contribution of other people. I don't need to know how to identity what all my terms refer to as long as there are experts around who do. (I can use 'molybdenum' to refer to molybdenum even though I have no idea how to identify samples; I can use 'beech' to refer to beech trees, etc.) This is Putnam's thesis of the "linguistic division of labor."

2. The contribution of the environment. Putnam thinks that kinds of things have (or often have) a nature that isn't apparent to casual observation. It may be this hidden nature that determines what some of our expressions refer to, even if we don't (yet) know what this nature is. Most (not all) of Putnam's examples are "natural kind terms," like 'water', 'gold', 'tiger', etc. Where we thing things have a hidden nature we don't know, we often intend to use words to refer to whatever has the same nature as the samples around here. This is basically the thesis Putnam calls "the indexicality of reference."