I wrote a follow up post trying to clarify the point I was making, to which a reader responded as follows:
The notion that values can transcend people and be defended in a disembodied form sound pretentious to me, and Platonist. There is no dichotomy between self/collective interests and what is considered 'good'. i.e. throughout human history, the 'good' has been constantly redefined to advance self/collective interests. This is just reality stripped of all self-serving pretensions, such as 'transcendent values', 'the good', etc.
I found this thought provoking and replied to it in the comments thread. But I'd like to add some further thoughts. The first is that if there is no definable good in life, then how can there be a self-interest? The term "self-interest" implies that there is some good in life that it is in our interest to obtain for ourselves. But if we refuse to recognise that such a good exists, then how do we make sense of the idea of self-interest?
This is something of a problem for various versions of liberalism. Liberals want people to pursue rational ends, but what can they be if there are no objective goods in life? Sometimes liberals resort to vague, nice sounding formulations like "human flourishing" as an ultimate, rational end. Classical liberals usually go for more tangible, material and quantifiable ends, such as property and physical security. At the collective level, the rational ends are thought, similarly, to be GDP growth, infrastructure and diplomatic power. This, though, represents a radical narrowing of the "rational ends" of life.
Marxism has a similar issue. Marx too thought, like my reader, that "the good has been constantly redefined to advance self/collective interests." He claimed for instance that in a capitalist society there was a bourgeois morality which advanced the interests of the bourgeoisie at the expense of the proletariat. The idea then is that the proletariat revolts and asserts its own class interests under the dictatorship of the proletariat. But from there the point is to remove all possible sources of "other" morality. So there is a withering away of the state (no government). No more nations. No families. Just the individual no longer subject to any sort of "false morality" by which individuals might serve the interests of others.
But what then? How does the individual live rationally absent an objective good in life but without some other interest imposed upon him? It's perhaps no accident that Marx famously wrote little about this, though he did suggest that individuals would choose to engage in a variety of activities as they had a mind to do.
To get back to my original point, talking about self-interest usually presupposes some sort of good that it is in our interest to secure. So things become difficult if the idea of objective goods is denied. What then might the vision of "morality as self-interest" be?
Some might perhaps think it acceptable if the "good" was a basic, biological one, such as the instinct to self-preservation, i.e. to "life" whether of the individual or the race. Others might not name a specific good, but see things in terms of a contest of "who predominates," i.e. of who has the power to enact their will, whatever it might be (the left often seems to assume this kind of motivation, and it is embedded in leftist identity politics).
The traditionalist view is, in comparison, rich in goods. My reader is concerned, though, that "The notion that values can transcend people and be defended in a disembodied form sound pretentious to me, and Platonist".
I think it true of religious traditionalists that we do have a sense that the goods that we perceive have a meaningful, spiritual or sacred character - they are "transcendent" in this higher sense.
But I don't see why goods cannot be asserted in a more mundane way. If, for instance, you have ever observed the way a mother gazes on her newborn, and the response of the infant to her, then it is difficult to deny that this kind of mother love is a good in life. It can be asserted as a good strictly on its own terms, i.e. that it is inherently good as an act that has beauty and love embedded within it. It can also be asserted as a good in consequentialist terms, as being significant to the psychological development of the child.
And nations? You do not need Platonic forms to assert that traditional ethnic nations provide a deeper sense of belonging and identity for individuals, that they motivate social commitments, that they provide diverse and unique expressions of humanity, and that they connect people closely to a particular tradition, landscape, history and culture - to the point that they inspire the love and loyalty of those born into them.
I would argue, too, that the human mind is able to grasp abstract moral qualities, such as honesty, or courage, or nobility. We can talk about these intelligently because we know the quality being referred to and we recognise these as moral qualities regardless of whether they serve our interests or not.