Some comments on the quotes from chapter 1.
First paragraph. From chapter 2:
Smith argues against the notion of a world government. The universal endangers the particular, that is, the way of life of the citizens of a regime and:
Politics only takes place within the context of the particular.
What is the particular? The particular refers to a way of life. Is the particular just another name for nationalism, tribalism, ‘us’ and ‘them’?
Second paragraph. From chapter 4:
Plato and Aristotle argue that the best regime is the one in which the best rule. The problem is that what is best “in speech” (Plato’s Republic is city is a city in speech), may not be what is best for us in practice. Smith emphasizes that:
“political philosophy is an imminently practical discipline (chapter 3).
Plato hints at the problem when Glaucon (one of the participants in the dialogue, and Plato’s older brother) complains that the food Socrates describes as most suitable in the best city is fit for pigs. He wants some comforts such as couches and tables and relishes and desserts. Socrates acquiesces and makes the city less austere. What is simply best in speech, that is, the ideal, is not what is suitable for human beings. It is a mistake to see the Republic as a utopian model for an actual city. The demands it makes on us, for example, its breeding program, is as Glaucon might say, fit for pigs.
In addition, as the dialogue progresses, it becomes clear that the best have no interest in ruling. Smith returns to this problem at the end of week 2:
How are we to understand Socrates’s claim that the pursuit of justice requires him to turn away from public to private life?
Another problem is that in actual regimes the best are not simply best, but best relative to others. In the worst regimes they are the best of the worst. But here we must ask best in what sense. It may be they are the best at being the worst, the worst of the worst.
As a practical matter the small closed society is not a matter of choice unless we choose to expatriate to live I know not where. But this does not mean we should not think about the advantages and disadvantages in comparison to a more cosmopolitan order.
And here, considering the problem of immigration, we see how relevant these old white guys who have been dead for over two thousand years still are.
Third paragraph. From chapter 4:
The question of the relation between the best regime or the good regime, that is what is at issue above.
As to the question of what function the best regime plays in political science; what seems best serves as a model for what the good regime should strive to be, keeping the cautions stated above in mind. We strive for what is best without having knowledge of what is best. Thus, skepticism (in the zetetic sense - inquiry motivated and guided by knowledge of our ignorance as to the truth of the matter) and the necessity of living the examined life
Fourth and fith paragraphs. From chapter 4:
The good citizen is not the same as the good human being. The good citizen is regime specific. What is honored and rewarded in one regime is not the same as what is honored and rewarded in another. Even in the good regime there is an irreconcilable tension between the good citizen and the good human being. Even in Plato’s Republic the philosopher must be compelled to return to the cave in order to rule.
From this vantage point we can reexamine the rejection of the universal order. That politics is always about the particular should not be construed as a form of provincialism or maintaining the status quo. The good human being is not defined by the particular. The good human being is not regime specific. I am not sure where Smith is going with this and so I will leave it there for now for you to follow where it may lead.