Yeshe D. wrote:
So do you hold that causality (which in the Madhyamakan account is dependent origination), is a conventional truth which is ultimately erroneous?
Causality is ultimately unestablished.
Yes, that's exactly the point: the conventions of causality being refuted by Chandrakirti are (in the Madhyamakavatara) the conventions of Sankya and Yogacara. Of course, in employing the reductio method, he does not assert a positive account of causality......
The four types of conditions: cause, object, immediate, and dominant, are common to all Buddhist schools. Nāgārjuna's MMK and Candrakīrti's Prasannapadā demonstrate that these four types of conditions do not withstand analysis.
But this method and those arguments do not deny the Buddha's saying "When there is this, then there is that. With the cessation of this, that comes to an end."
These statements are conventional, taught with a purpose. Commenting on MMK 1.10, the Prasannapadā states:
The definition of condition as dominant factor (adhipateya) assumed here is this: a factor which, on being present, something arises, is the dominant factor of the latter. But as nothing is self-existent, all things arising in mutual dependence, how can the "this" be represented as a cause? And how can the "that" be represented as an effect? So although the dominant factor is defined, it has not been established.
(BTW, if you're reading Garfield's translation of the MMK, his translation of MMK 1.10 is questionable. Apparently he's trying to save Nāgārjuna from modern critics accusations of nihilism. But all such accusations are quite pointless; they fail to correctly understand the two truths.)
All the best,
Garfield is quite explicitly influenced by the Gelugpa presentation of the two truths, which you clearly reject. However, his translation of the MMK is usually acknowledged to be very reliable. One of my own teachers, who is from the Kagyu lineage and has actually given open minded teachings on Dolpopa (about as far away from the Gelugpa presentation as you can get) has recommended the Garfield trans as the best.....and I agree. His commentary one can take or leave; I personally find it very useful.
But if you're not satisfied with that, how about this from the intro of the Mipham commentary of Chandrakirti's Madhyamakavatara:
"It is however, important to bear in mind that, in this context [the discussion about causation] causes are understood exclusively in a substantial or material sense......the everyday notion that real effects are produced by real causes is a mistake; it cannot possibly be true. Causes and effects, so much a feature of existence, are, he [Nagarjuna] says, essentially definable only in terms of mutual dependence
; they are not real things in themselves."
Therefore, what is being undermined is the intrinsic existence of entities and the conventions of causality posited on that (erronerous) basis; not the the mutual relation (causal) between
"It is important to understand, however, that he is not trying to deny our experience of production and change, or of anything else in the phenomenal world
. That would be absurd; the world-process is all around us constantly, undeniably."
"The true status of the phenomena that we experience is not, therefore, to be found in their supposed real entity, but in their relatedness, their interdependence with all other phenomena. This is Nagarjuna's interpretation of the doctrine of dependent arising, understood not in the sense of a temporal sequence, but in the essential dependence of phenomena......Their interdependence is their emptiness of inherent existence."
Which means that:
"In fact, the ultimate is not separate from phenomena; it is the very nature of phenomena. The ultimate is what the conventional reality really is; the conventional is the way the ultimate appears. The two truths are never separate; the merge and coincide in phenomena. The difference is not ontological but epistemic."
If mutual dependence is denied, then dependent arising (causality) is denied, which means that emptiness is denied.