Ok, let’s have look at how conditionality is explained in DN 15 (Ven. Bodhi’s translation):
‘Jātipaccayā jarāmaraṇan’ti iti kho panetaṃ vuttaṃ, tadānanda, imināpetaṃ pariyāyena veditabbaṃ, yathā jātipaccayā jarāmaraṇaṃ. Jāti ca hi, ānanda, nābhavissa sabbena sabbaṃ sabbathā sabbaṃ kassaci kimhici, seyyathidaṃ— devānaṃ vā devattāya, gandhabbānaṃ vā gandhabbattāya, yakkhānaṃ vā yakkhattāya, bhūtānaṃ vā bhūtattāya, manussānaṃ vā manussattāya, catuppadānaṃ vā catuppadattāya, pakkhīnaṃ vā pakkhittāya, sarīsapānaṃ vā sarīsapattāya, tesaṃ tesañca hi, ānanda, sattānaṃ tadattāya jāti nābhavissa. Sabbaso jātiyā asati jātinirodhā api nu kho jarāmaraṇaṃ paññāyethā”ti?
“No hetaṃ, bhante”.
“Tasmātihānanda, eseva hetu etaṃ nidānaṃ esa samudayo esa paccayo jarāmaraṇassa, yadidaṃ jāti.
“It was said: ‘With birth as condition there is aging and death.’ How that is so, Ānanda, should be understood in this way: If there were absolutely and utterly no birth of any kind anywhere—that is, of gods into the state of gods, of celestials into the state of celestials, of spirits, demons, human beings, quadrupeds, winged creatures, and reptiles, each into their own state—if there were no birth of beings of any sort into any state, then, in the complete absence of birth, with the cessation of birth, would aging and death be discerned?”
“Certainly not, venerable sir.”
“Therefore, Ānanda, this is the cause, source, origin, and condition for aging and death, namely, birth.
So, yes, here birth is given as a necessary condition for death: without birth, there is no death. And I agree with you, it does not follow from this that birth is a sufficient condition for death. I am not sure, however, if DN 15 is meant as an exhaustive treatment of causality in dependent origination. I would suggest the point of DN 15, rather, is to focus on the ending of suffering, as seems to be implied by the opening statement of the sutta.
To fully understand the conditionality that applies in DO we need to take a broader look at the suttas. I believe the best place to start is with the abstract principle of conditionality, which invariably is followed by the standard set of twelve links. It reads as follows in Ven. Bodhi’s translation:
Iti imasmiṃ sati idaṃ hoti, imassuppādā idaṃ uppajjati. Imasmiṃ asati idaṃ na hoti, imassa nirodhā idaṃ nirujjhati. (e.g. at SN 12.21)
When this exists, that comes to be; with the arising of this, that arises. When this does not exist, that does not come to be; with the cessation of this, that ceases.
Here we have, I think, an almost perfect match with sufficient and necessary conditionality. “When this exists, that comes to be; with the arising of this, that arises” shows sufficiency, whereas “with the cessation of this, that ceases; with the cessation of this, that ceases” shows necessity. If we are to take anything as the paradigm of conditionality that applies for DO, I would say this is it. It seems to me that DN 15 does not give the full story, but instead focuses on a particular aspect.
So I guess this means that the Buddha goes beyond causality as understood in modern science?
The abstract principle I have mentioned above is equally applicable here; in other words, both necessity and sufficiency applies.
[quote=“freedom, post:16, topic:5726”]
For an arahant, when a feeling arose, he does not pay inappropriate attention to it. He does not generate any more feeling of that kind (the loop-back is cut). That feeling will cease by itself; therefore, there is not enough level/intensity of that kind of feeling so it cannot be used as condition for the corresponding craving comes to be.[/quote]
It is not the intensity of the feeling that matters, but only how you relate to it. If you understand it in the right way, you will never crave for it regardless of its intensity. It is the insight of the arahant that matters.