SN 24.2: can a phrase 'when this happens... that happens' be used for a full-fledged modus ponens?

An interesting piece of text from SN 12.68…

“My friend, although I have seen properly with right discernment, as it actually is present, that ‘The cessation of becoming is Unbinding,’ still I am not an arahant whose fermentations are ended.
It’s as if there were a well along a road in a desert, with neither rope nor water bucket. A man would come along overcome by heat, oppressed by the heat, exhausted, dehydrated, & thirsty. He would look into the well and would have knowledge of ‘water,’ but he would not dwell touching it with his body.
In the same way, although I have seen properly with right discernment, as it actually is present, that ‘The cessation of becoming is Unbinding,’ still I am not an arahant whose fermentations are ended.”

That’s interesting. If this is a possibility in your hypothetical scenario, why isn’t P ∧ Q also valid for the arising sequence of SN 24.2? Not that I subscribe to such a proposition, since a logical conjunction per se says nothing about the causal relations between P and Q. So, your P ∧ ¬ Q does not help you either, unless you are saying there is no causal connection between P and not-Q in your hypothetical scenario.

Firstly, let’s zoom in on the tail end of this passage -

Friends, I do not speak of form as ‘I am,’ nor do I speak of ‘I am’ apart from form. I do not speak of feeling as ‘I am’ … nor of perception as ‘I am’ … nor of volitional formations as ‘I am’ … nor of consciousness as ‘I am,’ nor do I speak of ‘I am’ apart from consciousness. Friends, although the notion ‘I am’ has not yet vanished in me in relation to these five aggregates subject to clinging, still I do not regard anything among them as ‘This I am.’

As SN 24.2 makes clear, once there is no appropriation of an Aggregate (ie not-P), it follows necessarily that the Self-view does not arise (ie not-Q). This gives us ¬ P ⇒ ¬ Q, which you conceded as correct here -

For your option 1, does it account for the disappearance of Self-view “This I am” from Ven Khemaka, even if the conceit “I am” has not yet disappeared? Are you suggesting that from ¬ P ⇒ ¬ Q, you can validly assert not-Q (ie no Self-view) implies P (ie there is clinging)?

For your option 2, does it account for the disappearance of Self-view “This I am” from Ven Khemaka, even if the conceit “I am” has not yet disappeared?

I’m not sure if SN 22.89 is helpful to your case, as a new premise is involved in that case, namely the conceit “I am”. All we can validly infer from this sutta is that even if Self-view has been extinguished in a Trainee, the conceit “I am” has not -

Friends, even though a noble disciple has abandoned the five lower fetters, still, in relation to the five aggregates subject to clinging, there lingers in him a residual conceit ‘I am,’ a desire ‘I am,’ an underlying tendency ‘I am’ that has not yet been uprooted.

If you would like to render this into a proper P, Q and R propositions and argument, I would be interested to see the dots.

I see your reference to SN 22.109. It mentions that she understands the 5 aspects concerning the 5 Aggregates, on account of which understanding she is counted as a Stream Winner. It seems to me that this is a sutta which compresses what is expanded elsewhere as seeing the Aggregates as impermanent, suffering and therefore not-Self, eg SN 22.16.

As for your reference to SN 22.110, I’m glad you pointed out the absolutive viditvā. It does point to some earlier time frame. The verb is also different from the verb used in the preceding sutta (pajānāti) which may suggest that the Stream Winner’s vision is not as clear as the person on the cusp of Arahanta, echoing Bhante @Sunyo 's post . I would have little difficulty in agreeing with you that in the case of the arahant, there is no appropriation whatsoever. But how does this bear on the issue of the Stream Winner who does not appropriate the Aggregates as Self? In the Stream Winner, that’s one specific type of appropriation abandoned (including the other 2) but I don’t see any mention of the Stream Winner abandoning all appropriations. There are the 5 Higher Fetters that need to be accounted for.

Coming back to my proposal for P ⇒ Q for the arising sequence. There is also the simile of the dog on a leash in SN 22.99 and 100. The “regarding” of the Aggregates is framed just like the regarding in SN 22.8. The simile suggests that the yoke is inexorable and unavoidable in the Worldling. If this is so, how can there ever be a situation where there is appropriation of form etc that does not lead to Self-views?

I don’t see any remotely cogent argument here. I withdraw.

And finally, something else that conforms to P ⇒ Q, ie clinging to the Aggregates is a sufficient condition for Self-view.

In SN 12.20, apparently this is what’s impossible-

“When, bhikkhus, a noble disciple has clearly seen with correct wisdom as it really is this dependent origination and these dependently arisen phenomena, it is impossible that he will run back into the past, thinking: ‘Did I exist in the past? Did I not exist in the past? What was I in the past? How was I in the past? Having been what, what did I become in the past?’ Or that he will run forward into the future, thinking: ‘Will I exist in the future? Will I not exist in the future? What will I be in the future? How will I be in the future? Having been what, what will I become in the future?’ Or that he will now be inwardly confused about the present thus: ‘Do I exist? Do I not exist? What am I? How am I? This being—where has it come from, and where will it go?

Seems pretty straightforward to me.

I interpret the reasoning as suggesting some come cause and effect correlation without it being logically necessary.

That is the result of my reading and assumptions/my ‘ladder of inference’ – not necessarily something explicitly stated in the text.