Okay, so for (b) we agree that China does not want to agitate a war with the US; that it would like to avoid it.

For (a) you do not have an area of critique where you believe any chain of logic presented earlier in the thread in unsound. Instead for (a) you have an alternative theory that you would advance.

The reason I thought you had some critique of soundness in (a) is that you had commented earlier you thought there was wild mental gymnastics, which would imply that you thought there was some unsound/crazy/wild leaps of thought.

This I think leaves us to discuss (a). Your proposed alternative theory agrees on the premise that the US would be the one choosing to engage military with China - that China would not choose to attack the United States. The key difference in your theory is that the United States "begrudgingly" would be obligated to engage militarily with China such as due to a legal commitment. This is opposed to the characterization that I advanced, which is that the United States is "leaning into" reasons to engage militarily with China.

I can explain why I do not think that the US would "begrudgingly feel obligated" and instead is "leaning into reasons". This is quite simple (I will spare spilled ink).

The US established in 2009 that China was its primary rival (in 2009 the Obama Administration announces the "Pivot to Asia", which Wikipedia describes as "represented a significant shift in the foreign policy of the United States ... invest heavily and build relationships in [Asia] ... to counter [China's] rise as a rival superpower"). https://en.wikipedia.org/wiki/East_Asian_foreign_policy_of_t...

Since that time the reasons for a potential US conflict with China have kept changing. Once it was because of "unfair trade practices". It became for a while "Uighurs". "Tibet". "Defense of India". "South China Sea". "Taiwan". The constant over time is the explicitly and carefully articulated reason given by the US government itself that it needs to counter China as a rising superpower. The areas of conflict have been, are, and will continue to be, subject to change.

The US had almost certainly has no legal obligation to intervene on part of its "allies" (the Philippines only unless you have other legal allies in mind?) nor does it have any obligation to intervene for Taiwan. From a legal perspective again the Mutual Defense Treaty with the Philippines (who I assume you refer to by "allies") was effectively dead (with US bases, soldiers, exiting the region by early 1990s). It was only in 2021 (!) long long after the US identified the need to confront China that the US renewed this treaty (after the Philippines suggest it be scrapped). Neither the Philippine's specious claims to the Spratly Islands the a BRP Sierra Madre scenario would obligate a US intervention.

I would add that the US even insisted on intervening on behalf of the Philippines even when the Philippines itself rejected the United States and called for it to not engage in the area. This is how desperate the US has been to try to engineer something here. (The new Philippine administration has been easier for the US to work with).

Indeed the United States has been accelerating its efforts to grow treaties, obligations, and military basing in China's near abroad. From the Compacts of Free Association to the Nuclear "AUKUS" to the Quad, to its quite scandalous attempt at the Trans Pacific Partnership, the US's foreign policy has attempted to constrain the growth of China and attempted to engineer plausible scenarios in which it might escalate tensions with China into a victory.

China's interest in the South China Sea? To prevent an existential economic blow severing its ability to trade, a la the blockade that occurred during the Anglo-Chinese War. (Interestingly, and an aside only, Taiwan agrees with the Republic of China on Qing and earlier Chinese historical rights to the area).

Regarding such a confrontation? What would a war scenario look like? It would involve much more than the defense of the Sierra Madre or the defense of the Taiwan strait. The US military's footprint and conflict plan escalation from where-ever a conflict may arise to a blockade and strikes into China, even if it is not operationally called for (to defend a littoral, or whatever).

The US and Taiwan? The US's policy since the inception of relations with the island (despite being legally obligated to recognize Taiwan as part of the Republic of China) has been "strategic ambiguity" - to be purposefully vague about whether it will come to the defense of the island in order to discourage the status quo from changing.

The US, only after identifying its grand strategic need to prevent the rise of its superpower rival, has changed this policy, explicitly stating the US will defend Taiwan (again, no legal obligation) to encourage it to declare independence (again - despite US legal recognition).

US President Trump - China hawk of China hawks - first action as president was to call the leadership in Taiwan, a protocol breaking and intentionally provocative move intended to signal the US's intention to rock the boat and agitate for conflict with China.

I submit to you the "Pivot to Asia". The US first identified the need to confront a rising China as a rising superpower competitor more than a decade ago, and has since found various potential plausible means by which a conflict might occur and the US might escalate to situation in which China's potential is diminished.