In §293 Wittgenstein considers what it would be if “pain” were a name for a particular kind of inner experience and goes on to show how this picture cannot make sense via his beetle-box example, discussed shortly.
Suppose that I know what the word “pain” means only from my own case – that is, I know it as a name for a particular sensation that I have. If this is how I know the word, then this must also be how others know the word – that is, Sam knows the meaning of “pain” from his own case, as a name for a particular experience of his, something inward. In order to ascribe “pain” to others, it seems I have to generalize from my own case, something like “When I say I’m in pain I feel this way, so when others say that they are in pain, they feel that way too.” The justification for this generalization is dubious, for I only know one case of application (my own), and cannot infer that others are using it the same way (since I don’t have access to their inner experience). This cannot be the right picture of how I know the word “pain”. We’ll now elaborate.
Intuitively, it seems that someone can only know what pain is from their own case. Let’s take this intuition seriously and consider the following example. Suppose everyone has a box with something in it called a “beetle”. No one can ever look into anyone else’s box (it is logically impossible), and everyone says he knows what a beetle is only by looking at his own beetle. (We can think of the box as a person’s mind, the beetle as the particular sensation that person has – and the person knows what the beetle is in his own case. In this way, there is analogy to the pain case. There is a sensation of pain [particular beetle] in the “mind” [box], and the public word for the sensation: “pain” [beetle].) In this example, the contents of each person’s box may differ – we can even imagine the contents changing—“beetle” simply designates the box-contents regardless of what is or is not in them.
In this situation, we cannot say that Sam knows what a beetle is only by looking at his own beetle. Why? Suppose Sam has an orange in his box. You ask Sam “what’s beetle?” He can either say (1) an orange, or (2) whatever is in the box. If (1), we can’t say he knows what a beetle is because for all he knows a pear is in someone else’s box—if “beetle” denotes orange then it shouldn’t denote pear. If (2) then he hasn’t said what a beetle is, for he might as well have said “a beetle is a beetle” or “what is in the box is in the box”. Such an answer is not at all informative, and so not at all meaningful. This echoes §298, where Wittgenstein observes that the fact we’re inclined to say “This is the important thing” – while we focus on our particular inward experience – is sufficient to show how we are inclined to say something which is “not informative”. One cannot know the meaning of “beetle” just from looking at his own beetle.
Now let’s suppose that these people had a use for the word “beetle”. That is, suppose “beetle” is in fact a meaningful expression. If so, “beetle” couldn’t be a name for a kind of inner experience, for the same reasons stated in the previous paragraph. We cannot name the thing in the box; for suppose someone’s box is empty, “beetle” cannot stand as a name for an orange and as a name for emptiness – we cannot refer to the particular (non)object in any one’s box because it’s contents aren’t part of the language game – whatever it is cannot be shared or expressed, for a private sensation cannot even be given a name that others (or even yourself) can understand. The object in the box is not an object of possible reference, there is no public word for one’s private contents, as we saw in §258. If the word has a use, its use is as something other than a name – it can be publicly understood. If “beetle” has a meaning, it cannot be a name. The idea is that if mental predicates like “pain” are names denoting a kind of object, the object “drops out of consideration as irrelevant” – we can’t actually make sense of our referring to that object. If the word only ever has a public use – is publicly understood – then it cannot ever be used a name for a private object. When I say “I am in pain” I express something we all understand – I do not name a particular inner sensation present to me – this is the sense in which the object “drops out of consideration as irrelevant”.
§291 buttresses this point. Consider that you might think of a description as a kind of name for an object—“a word-picture of the facts”. On this view, there’s a sense in which the description is idle, it simply depicts a state-of-affairs. But now consider how an engineer might use a description. Drawing a machine, a sort of design, is like a description of what he will build. Recording a measurement is a description that he uses to know where put things or how to put them together. These descriptions have particular uses – they are not “idle”. If we think of words as names for objects, they become idle; if we realize that words have uses (over and above naming objects), we see that words are not mere pictures but rather tools for doing things. The engineer’s description gets its meaning from its use or place in some project – not as a name for his inner imaginings. If we want to grasp the meaning of a word, we must look to its use; if words are merely names for objects (especially for inner qualities), we cannot make sense of how we can use them meaningfully.
The example in §293 does not show that there is or is not any particular sensation that one stands in relation to. Rather, it demonstrates that the grammar of our language doesn’t allow for this kind of private reference or knowledge of meaning (§304). There is no place in the language for a name for a private sensation, for there is no sense in which we could understand what we are referring to. Insofar as words have uses – and, consequently, meaning – they must be used to talk about something other than private mental contents.