Ludwig Wittgenstein, answered from the texts and cited to the page.
Following a rule is a practice.1 Not an interpretation, not an inner voice, not a mental rail that determines each next step — a practice, embedded in training, exhibited in what we call "obeying" and "going against" from case to case. Consider what happens if you replace the practice with inspiration. An inner voice tells you "draw this way." You await direction at each step.
You cannot teach anyone else your technique — at most you can teach a kind of receptivity, a way of listening. But then you cannot expect him to follow the line as you do.2 That is not following a rule; it is composing. The difference is not one of inner experience but grammatical: following a rule is the kind of thing that can be taught, that produces agreement, that makes "correct" and "incorrect" application intelligible.
The temptation is to say: every action according to a rule is an interpretation. But one should speak of interpretation only when one expression of a rule is substituted for another.3 If every application required a further interpretation, nothing would ever be settled — the regress never terminates in something that actually guides. What terminates it is not a deeper interpretation but the bedrock of practice itself: I was trained to go on this way, and I go on this way, and that is what following the rule consists in.
This is why it is not possible to follow a rule privately.4 To think one is following a rule is not to follow a rule. The private case collapses the distinction between "it seems right to me" and "it is right" — and where that distinction collapses, we cannot speak of a rule at all. There is also no hidden wheel to catch hold of, no right machine which, once chosen, carries you on automatically.5
Someone who has genuinely grasped a rule will continue the series correctly — but what "grasping" consists in is shown in the continuation, not in some prior inner act of apprehension. "Once he has seen the right thing" — but this right thing that I mean does not exist as an object he latches onto. The rule produces all its consequences in advance only insofar as I draw them as a matter of course, the way I call this colour "blue" as a matter of course.6
The emphasis of "must" in "if you really follow the rule, it must come out the same" corresponds not to some logical compulsion hovering above the practice, but to the inexorability of an attitude — one that comes out everywhere in our lives, in innumerable related practices, not merely in calculating.7 The "must" is a feature of the grammar, not a metaphysical force.
And what does teaching the rule look like at its foundation? I teach someone to continue a series by showing examples, without any expression of the law of the series — forming a substratum for the meaning of algebraic rules, not deriving the continuation from a formula.8 The "and so on" in any formulation of a rule already presupposes that one has mastered a technique; it cannot do the founding work by itself.9
That's why 'following a rule' is a practice. And to think one is following a rule is not to follow a rule.Philosophical Investigations, pp. 112–114
In the case of inspiration, I await direction. I won't be able to teach anyone else my 'technique' of following the line. Unless, indeed, I teach him some way of listening, some kind of receptivity. But then, of course, I can't expect him to follow the line in the same way as I do.Philosophical Investigations, pp. 118–119
That's why there is an inclination to say: every action according to a rule is an interpretation. But one should speak of interpretation only when one expression of a rule is substituted for another.Philosophical Investigations, pp. 112–114
And that's why it's not possible to follow a rule 'privately'; otherwise, thinking one was following a rule would be the same thing as following it.Philosophical Investigations, pp. 112–114
There is no such thing here as, so to say, a wheel that he is to catch hold of, the right machine which, once chosen, will carry him on automatically.Zettel, pp. 58–60
The rule can only seem to me to produce all its consequences in advance if I draw them as matter of course. As much as it is a matter of course for me to call this colour 'blue'.Philosophical Investigations, pp. 118–119
The emphasis of the 'must' corresponds only to the inexorability of this attitude, not merely towards the technique of calculating, but also towards innumerable related practices.Zettel, pp. 58–60
I teach him to continue a series (basic series), without using any expression of the 'law of the series'; rather, I am forming a substratum for the meaning of algebraic rules or what is like them.Zettel, pp. 58–60
But what does he mean by that? For the 'and so on' presupposes that one has already mastered a technique.Zettel, pp. 58–60