I will be the proponent for ethnonationalism, which I would argue is the most effective way of preserving Western Culture from the threat posed by mass immigration in particular, as well as a commonality through Western History. I argue that what we call Western Culture is if not a product of white people specially, it is currently only held by them in enough numbers to matter and no way of fixing that is known

Civic Nationalists, my opponent especially, recognize the threat Progressivism and Mass Immigration pose to the West. And their proposal is to have society adopt a civic identity based on some variety of classical liberalism and extend this to a selective immigration policy. While appealing, a non-racial method of determining citizenship and selecting only the best, I believe this system and its proponents underestimate the challenges inherent to civic identity and the challenges both progressivism and demography pose for them.

They are forced into a balancing act of maintaining diversity of opinion, a commitment to a central value which is difficult to test for without crushing viewpoint diversity, an unspoken dislike for the chauvinism which their system would need to regulate itself, a professed acknowledgement of the issues diversity poses, putting contemporary ideas of Western culture which will go out of style before the reality that a racial group holds the ideals that made the West as they see it, uses an idea of merit to bring in bright members of other groups who in no way share the values of the majority to form a new elite, resisting corporate and political pressuring to bring in the not-so bright to fill labor shortages which can also be classified as merit, and the central mistake in assuming there even is a unified idea of Western Culture rather than a flux of competing and sometimes contradictory ideas entertained by Westerners.
And this is before the fact that values go in and out of style, and that Progressivism is a cluster of intellectual fads which have dominated our elite institutions despite the public scarcely agreeing with them. This further tests the idea of even a unified value system within nations at a given time, and the idea that their preferred conception of our values will stand the test of time. They can say it does not have to but we are living in an era of a maladapted civic identity: that the West is about diversity and openness or that the West needs to be fixed by diversity in some way. Our policies are about maximizing this (section 8, diversity lottery), there isn't a lack of policy but a perverse conception of what we are as a civilization

Ethnonationalism, here defined by policies which maintain an ethnic or racial group's demographic hegemony and continuity in a society, on the other hand acts as demographic insurance. It does not necessarily mean no skilled immigration but puts a limit of immigration of any kind. It lasted for the West's entire history until the 1960s while any talk of assimilating immigrants since then was just talk. It preserves viewpoint diversity as the dominant group will decide for itself what values it wishes to have in society, it has the amount of chauvinism needed to make good on an immigration regime in that it has no qualms in deporting violators,  it more than claims to understand the issues of diversity, accepts that our conception of our culture will change but it will be on our terms, recognizes that elite outsiders can alter society more than many non-elite outsiders, has a clear objection to a large influx of low skilled which can't be easily talked away by moneyed interests (netanyahu), and recognizes Western Culture is in many ways a contest but wont let one side bring in support from the outside. As such I contend it is the superior system

1. Civic Nationalism will either be toothless or basically thought-policing people who come in, when a diversity of values is actually good

2. Civic Nationalists cant even define Western Culture or how to detect it in prospective immigrants or how they will 'assimilate people'

3. Ethnonationalism just has to achieve ethnocultural continuity, not 100%

4. Based on PISA scores, Australia and Canada see very marginal benefits (if any). A nation like Singapore, despite a high starting IQ, sees noticeable benefits and has policies to maintain a Han supermajority. So there isnt a reason to not have some element of racialism

5. Their civic identity will go out of style or be redefined later on

6. They wont get their ideal system but some weaker compromise. So it seem irresponsible to not have an element of racialism as 'insurance' in a sense. Saying Civic Nationalism will be "just as good" as ethnonationalism in preserving the West, in my opinion, is a dodge with this in mind. It could be just as good but you wont get your ideal system so why not be honest and add an element of racial particularism to proceedings?

And lastly, practically speaking some kind of civic or meritorious system will likely see groups like North East Asians benefit the most. And the Chinese in particular. And there are very good reasons to be wary of that, despite (and in some cases because of) their higher IQ. They have their own nations to run as they see fit, and there are many traits I do not wish to be imported to our nations despite my desires to emulate them in other respects. Moreover, there is every reason to believe an ascendant nation like China is perfectly happy to send its coethnics around the world to form a segment of society sympathetic to their homeland. This is a practical danger, High IQ groups, can alter society for the worse too.

>high IQ groups

why cant they be with their fellow brights rather than let us dummies bring them down? Or is it because IQ is important but something sets the Westerner apart even from higher IQ societies? East Asian societies are more corrupt and prone to big overbearing government. Particularly Korea and China where the bulk of northeast Asian immigrants are from now. They also show no compunction in asserting themselves collectively in their own lands and would here if they predominate. Or they'd just recreate the same conditions here. Maybe they wont but we cant exactly repeat the experiment if it goes awry, so I see no reason why we should accept too large a number of them because of their IQs. Their IQs arent being held back in their home environments so they could outcompete us over there if they wished. No need to let parts of white civilization become an outpost of their's by letting in too many as New Zealand, Canada, and Australia are seeing