Let’s get back to the task at hand and apply the definition to these claims:

Not every mammal is suitable to keep as a pet. After all, tigers are very aggressive and can cause serious injuries to people.

Is this an argument?

Is there a claim in here that, if true, makes some other claim more likely to be true?

Yes, there is.

Let's say it's true that tigers are very aggressive and can cause serious injury to people. It’s not hard to imagine since our world is precisely one in which the claim is true. Hence, isn’t it more likely to be true that “not every mammal is suitable to keep as a pet”? Yes, because we just said that tigers are aggressive and can maim people. And right there, we’ve teased out support. One claim’s being true makes it more likely that the other claim is true.

Conclusion: Not every mammal is suitable to keep as a pet.
Premise: Tigers are very aggressive and can cause serious injuries to people.

The only other alternative would have been to start with imagining a world where “not every mammal is suitable to keep as a pet.” So like this:

“Premise”: Not every mammal is suitable to keep as a pet.
“Conclusion”: Tigers are very aggressive and can cause serious injuries to people.

Would that make sense? Well, let’s play this out. I am imagining a new world. In that world, it is true that some mammals are not suitable as pets. Does that “premise” make it more likely that “tigers are very aggressive” or that “tigers can cause serious injury to people”? No, I don’t think so.

Now, look, if you said, “Wait, J.Y., have you been living under a rock? You don’t know that tigers are aggressive and they can hurt people?” then you’re not playing the game right. Of course we all know that tigers can hurt people. But the important question is how do we know that? We know that because of our knowledge and experience of living in our world. Crucially, it’s not because “not every mammal is suitable to keep as a pet.” That claim just says that some mammals are not suitable as pets. That claim doesn't tell us which mammals are unsuitable. Gorillas, zebras, polar bears, or what? I also don’t know why they’re not suitable. Is it because they are smelly? Or is it because they might eat you if you forget to feed them lunch?

So you see, the fact that "some mammals aren't suitable to keep as pets" gives no support to the claim that tigers are aggressive.

It’s very important to play this game right. When trying to identify an argument and its components, you’re not simply asking yourself, “Is some claim C true?” If you only asked yourself that, you've forgotten about the relationship. That's a psychological stumble that the test writers will ruthlessly exploit, and I'll show you how they do it in future lessons. Rather, you should be asking yourself, “If I imagine a world where this claim P is true, does it make it more likely that this other claim C is true?” That’s a big difference.

LET’S REVIEW

To figure out whether there is support between a set of claims, ask yourself if the truth of one of the claims would increase the likelihood of the truth of another claim. Be careful not to confuse that with the question of “Based on my knowledge of the world, do I know if this claim is true?”