Somewhat related: Nirvana fallacy, where it is automatically assumed that the comparative is some perfect state, and the suggestion is criticized as being the worse of these two options.
Yeah, I think being comparative is one of the most important but oft-ignored aspects of debating. It not only creates a comprehensive vision of the world that either gov or opposition wants, but it also serves to ground arguments to deliver a very tangible impact.
I often see 'not being comparative' as a failure mode of many, many models. Some examples of what I've encountered:
This therapy has saved people from cancer (yes, but how many in comparison with the official therapy?)
Such and such leader knows NLP (yes, but many leaders in comparison do ignore it?)
Such and such people managed to get thinner with paleo (yes but how many people didn't? And how many people lose weight with other kinds of diets?)
You get the idea.
but if the speaker had only talked about this, then the argument would have been weaker.
Would it? What is he arguing for?
That may be a difficult question, but it seems prior or more fundamental than the comparative.
If you don't talk about what the comparative is, then other people will have their own image in their mind about what it is. So some people might think that the comparative is cosmopolitanism, but if you explain why that doesn't work (okay, I just stated it was unrealistic, I didn't say what it wouldn't work) it is more likely that they will adopt your conception of what the comparative is. I will note this is especially important in debating where if you fail to address the comparative, the opposition is free to paint it as being whatever they want to claim that it is.
Not only are you ignoring the fact that the speaker conflated different claims or positions, you just did it yourself with this word "cosmopolitanism."
"The comparative" can avoid certain rhetorical tricks that are harmful to real discussion, but your example is a more pernicious trick.
I'm actually summarising someone else's argument - an argument made in the linked video.
The point is that when people discuss the comparative, it makes the discussion more explicit, as we know that they are comparing A to B, instead of C to B.
In order to get a solid handle on a proposal, it isn't enough to just know what the world will look like if you adopt the proposal. It is also very important to know what the current situation or counter-model is, otherwise the proposal may provide less of a benefit than expected. Before I begin, I'll note that this article is about the comparative, I'll write another article for being comparative later, though probably under the name being responsive since this will be less confusing.
One of the best ways to think about what it means to be comparative is that you want to indicate what the two worlds will look like. For example, conscription may provide us with more troops and everyone might agree that troops are important for winning wars, but we also need to look at what the status quo is like. If the country already has enough troops or allies, then the difference in the comparative might not be that significant. When we ignore the comparative, we can often get caught up in a particular frame and fail to realise that the framing is misleading. At first, being able to better win wars might sound like it is really, really important. But when we ask the question of whether or not we need to be better at winning or if we are good enough, we might quickly realise that it doesn't really matter. As can be seen here, there is no need to wait for the other team to bring arguments before you can start being comparative.
Here the first speaker in, This house supports nationalism, provides a good example of being comparative. He explains that he doesn't see the comparative as being some utopian cosmopolitan society, but that people will always choose a particular form of identity. He say that this should be nationalism; not ethno-nationalism, but rather a form of nationalism based on shared values. He argues that this is advantageous since everyone in a nation can opt into this identity and hence it avoids the divisions that occur when people opt into specific identities such as race or gender. The speaker also talks about how nationalism can energise the nation, but if the speaker had only talked about this, then the argument would have been weaker. In this case, thinking about what the world would otherwise look like allows you to make nationalism more attractive since we can see that the alternatives are not particularly compelling.
As another example, consider a debate about banning abortion. Imagine that the government stands up and talks about why they think the fetus is a person and hence it should be illegitimate to abort it. However, their argument will not be as persuasive if they fail to deal with the comparative, which is that many women will get abortions whether or not it is legal and these abortions will be more dangerous. In this debate, the comparative weakens the affirmative case, but it also allows the government to pre-emptively respond to this point. This objection is also common knowledge, so unless this is responded to, this analysis will likely be rejected outright.
So, as we have seen, being comparative allows you to be more persuasive and to think in a more nuanced manner about an issue. It provides the language to explain to a friendly argumentation opponent how you think their argument could be improved or why you don't think that their argument is very persuasive.