This is the final skill in argument mapping that we’ll discuss. It’s very important to be aware of because without it we can only ever map parts of a discussion which agree with one another. Meaning that if someone has an objection to an argument, we won’t be able to pinpoint where the disagreement is on our argument maps. Our argument maps are more expressive and powerful if we can diagram disagreements as well as agreements, so let’s discuss how to map disagreements!
We need to have a tool to map objections to an argument that we’ve already mapped so we can see where those objections are “putting pressure” or what exactly they’re trying to critique.
We use either hashed arrows or dotted arrows to signify relations of objection. They mean “objects to” or “rejects”.
These are the only arrows in our system which point up.
There are two kinds of objections:
1. Objections to a proposition
- Analyst A: (1) Building this highway would threaten the existence of the species of fairy shrimp that inhabits the proposed route, so (2) we must reroute the highway.
Analyst B: I understand your concern for the fairy shrimp, but (3) the proposed route is not the only habitat for the fairy shrimp in this area, so it wouldn’t threaten their existence.
Note that the arrow is pointing to the Premise.
2. Objections to an inference
- Obama said that (1) people who were brought here illegally as children shouldn’t be punished for the choices of their parents, because (2) their parents made the decision and not them. But that doesn’t follow because (3) we’re not punishing them, instead we’re just enforcing our laws.
Note that the arrow is pointing to the other Arrow.
Could have also used a dotted arrow.
Here’s a weird case, so that you can see what sorts of situations you might get into when trying to map objections:
Notice how objection 7 has to cross over an inference to point to the inference from 3 to 1. That’s okay. But it helps to keep your argument maps a bit larger and as clear as possible. You want to be able to clearly decipher what’s going on in the argument map as you go along.