I've just thought of a comparable situation that might help make the above distinction clearer...
Think of the Buddha's teaching of anatta, (not-self) which says that the five aggregates and six-sense-sphere are not-self. Not once does the Buddha make the ontological declaration that "atman doesn't exist"*
. When Thanissaro Bhikkhu explains this point and shows it's not an ontological teaching, some Theravadins who cling to an ontological belief in the non-existence of atman/soul hurl all manner of insult upon him because his comments do not affirm their pre-existing ontological bias. The teaching of anatta is most valuable as a corrective to those whose ontological biases (i.e. belief or disbelief in atta or atman) cause them to incorrectly discern/regard loka in the present moment.
Now think of the Buddha's teaching of dependent origination, which says that all experience other than nibbana is conditioned/formed/sankara. The Buddha doesn't affirm either ontological existence or non-existence. When Nanananda, Nanavira et.al. explain this point and show that dependent origination is not an ontological teaching, some Theravadins who cling to an ontological belief in existence, exude all manner of strange looks and accusations of obscurity, because their comments do not affirm their pre-existing ontological beliefs. The teaching of dependent origination is most valuable as a corrective to those whose ontological biases (i.e. existence or non-existence) cause them to incorrectly discern/regard loka in the present moment. Let's not kid ourselves either, that's true of all putthujjanas, and of sekhas who habitually still lapse into avijja, when not mindful. As Nanananda says, "We are not willing to accept that existence is a perversion. Existence is suffering precisely because it is a perversion.”... so I'm not just talking about one or two people, I'm talking about all of us here (unless the self-proclaimed arahants in the member poll are to be believed!
). Whether an individual wishes to strive to see that existence is a perversion and put an end to suffering is up to them. The Buddha, Nanananda, Nanavira et.al. can only point the way... speaking for myself though, it is of paramount importance.
As dependent origination addresses and diagnoses the full gamut of ontological beliefs, it is rightly regarded as the most profound of the Buddha's teachings. Anatta, whilst not quite so profound, is still immensely valuable since so much of our preconceived ontological beliefs which give rise to clinging are rooted in notions of self (e.g. "I" and "mine"). So yes, paticcasamuppasa does address ontological biases in the form of belief and disbelief in the soul, and belief and disbelief about what happens to it at death... but that's not all it does. Because it talks about atthitā (existence) and natthitā (non-existence), rather than sassatavada (eternalism) and ucchedavāda(annihilationism) it encompasses all
ontological views/distortions, including but not restricted to the distortions of sassatavada and ucchedavāda, plus distortions attributable to belief or disbelief in God. Thus, it serves as a corrective against all distorting biases
. That is why it is awesome.
In the context of a "Buddhist response to Western ontology" it renders the need for such responses to make reference to God completely moot.
* - Why he refrains from doing so is quite obvious, if you think about it. If he did ontologically deny atman, he could not prove it, because to prove it he would have to explain something outside the all. Being unable to prove it, he would not be able to wedge people out of their deeply ingrained beliefs. Ditto with those who cling to views pertaining to God and his existence/non-existence. Therefore, the Buddha tries to get them to focus just on their experience/loka and logically demonstrate to them that nothing within that loka is atman. Now that is personally verifiable and onward leading... and that is how you get people to relinquish entrenched views in favour of something more liberating.