Milky wrote:

Now, watch my lips. In BrEng, IMO: non-epistemic have to (external/deontic) non-epistemic must (internal/bouletic (for some, also called deontic)) What more is there to say?

Well, it doesn't reflect the BrE I speak, write, and hear in London and southern England every day. Perhaps it's commoner in other areas. Which part of England do you live in?

Two general points.

1. The nature of the "rule"
As you've already conceded, not every BrE speaker/addressee treats "must" as invariably "subjective" and "have to" as invariably "objective".

There may well be occasions where a speaker uses "must" to imply a subjective obligation, or "have to" to imply an objective obligation, and where the addressee does indeed interpret them as such.

But if a speaker uses "must" to imply a subjective obligation, the addressee is not necessarily "wrong" to infer an objective obligation. (Perhaps he does not apply the distinction himself; perhaps he does not know whether the speaker applies the distinction; perhaps the context is obviously "objective".)

Similarly, if a speaker uses "have to" to imply an objective obligation, the addressee is not necessarily "wrong" to infer a subjective obligation.

Our very disagreement disproves the Palmer-Thompson hypothesis. If two BrE speakers are able to devise different interpretations for utterances even within context, there is clearly more to "must" and "have to" than a simple dichotomy would suggest.

2. The nature of "subjective" and "objective" obligations
It's very difficult to think of a subjective obligation that doesn't have an objective aspect, or an objective obligation that doesn't have a subjective aspect.

From your position, therefore, when you interpret a sentence, you can naturally always find the aspect that supports your rule. If you look for the two faces, you'll find two faces; if you look for the vase, you'll find the vase.

If you can find an example of deontic "must" that has no conceivable objective aspects, and an example of deontic "have to" that has no conceivable subjective aspects, we may be able to identify the areas where your rule does indeed invariably apply.

But otherwise, it's simply an attempt to fit something intrinsically fuzzy and messy into tidy Sunday School categories.

MrP

<2. The nature of "subjective" and "objective" obligations
It's very difficult to think of a subjective obligation that doesn't have an objective aspect, or an objective obligation that doesn't have a subjective aspect. >

Share with us, if you will, your definition of the words subjective and objective. What about morality? What do you mean by it when you use it in these pages.

Milky wrote:

Share with us, if you will, your definition of the words subjective and objective. What about morality? What do you mean by it when you use it in these pages.

For convenience and consistency, I'm using "subjective" and "objective" in the sense this post of yours implies:

Milky wrote:

I must get a haircut. (Internal/psychological/subjective opinion) I have to get a haircut. ( External/non-psychological/objective opinion) In the first, the speaker thinks it's time to get a haircut, while in the second, the speaker understands that people more than he/she would think it was time to get a haircut.

I don't believe I've referred to "morality".

MrP

Milky wrote:

<For convenience and consistency, I'm using "subjective" and "objective" in the sense this post of yours implies:> And how do you know what I mean by those words?

I take the meaning you offer in your post. It's not unusual.

My view is simply that the Thompson-Palmer hypothesis doesn't fit the facts.

I've illustrated it by showing how your own interpretations of "must" and "have to" differ from post to post and thread to thread.  

Well, okay. I'll look at them tomorrow.

MrP