Kinds of Argument Structures

I'll give standardizations here for the major argument types. Corresponding diagrams will be done in class - make sure you're there.


Simple Arguments

Simple arguments have one "layer" of premise. That is, no premise also functions as a conclusion


1.
Single Support Arguments

Example:

I think I should buy this used Toyota Corolla. Why? They're practically giving it away.

P1: They're practically giving it away.

MC: I think I should buy this used Toyota Corolla.



2.
Convergent Support Arguments: If a premise can stand on its own, that is, if it adds to the likelihood of the conclusion being true on its own, and there is more than one premise like this, we have a convergent argument.

Example:

I think I should buy this used Toyota Corolla. It is in good shape, it gets good mileage, and besides, it is within my budget.

P1: The car is in good shape

P2: It gets good mileage

P3: It is within my budget

MC: I should buy this used Toyota Corolla




3.
Linked Support Arguments: We link premises when it is clear that a premise by itself will not lead to the conclusion. It is a question of relevance.

Example:

I think I should buy this used Toyota Corolla. I need a car, and I like this one.

P1: I need a car

P2: I like this car

MC: I should buy this used Toyota Corolla

Note that neither premise can stand by itself. Could the argument be, "I need a car, therefore I should buy this used Toyota Corolla."? No, because we might ask, why this car? Could it be "I like this car, therefore I should buy this used Toyota Corolla."? No - just because you like a car doesn't mean you should buy it. Both premises are needed together.



Complex/Extended Arguments

Complex or extended arguments have more than one layer of premise, or deviate in some other way from the simple argument. Premises also function as conclusions in smaller arguments, or they may stand against the main conclusion, as in counterconsiderations. These arguments make use of any or all the forms of simple arguments.

Example:

I think I should buy this used Toyota Corolla. I need a car, because I have to get to work and the bus isn't convenient. This car seems to fit all my requirements: it is cheap, it is in decent shape, and I like the colour. Plus, I'd be doing a favour for my friend, who is selling it, because she needs the money for school.

P1: I need a car

P2: I have to get to work

P3: The bus isn't convenient

P4: This car fits all my requirements

P5: The car is cheap

P6: The car is in decent shape

P7: I like the colour

P8: I'd be doing my friend a favour

P9: She needs the money for school

MC: I should buy this used Toyota Corolla


Counterconsiderations

Sometimes a person takes into account arguments against his or her conclusion. These need to be sketched as well. For example:

I think I should buy this used Toyota Corolla. Despite the fact that the mileage is high and it is more than I can afford, I really like it.

P1: The mileage is high

P2: It is more than I can afford

P3: I really like it

MC: I should buy this used Toyota Corolla


In this case, we show that there are counterconsiderations by drawing a
wavy line between the premises that go against the conclusion, and the conclusion itself.


Multiple Main Conclusions

In rare cases, a person may argue for more than one main conclusion. Sometimes these can be separated out as different arguments; sometimes they can't and need to be left together. Separate main conclusions are used when the elements seem unrelated, that is, one conclusion could be true and the other not. Example:

I think I should buy this used Toyota Corolla, and drive across the country to San Francisco. Buying this car is a better idea than just flying, because I'll have something to use when I get back. Besides, I've always wanted to see the US.

P1: I'll have something to use when I get back.

P2: Buying this car is a better idea than flying.

P3: I've always wanted to see Canada.

MC1: I should buy this used Toyota Corolla.

MC2: I should drive across Canada to Halifax.


In this case, the writer could argue for buying the car without travelling, or for travelling without buying the car. The writer has made a connection between these two, but they still seem like separate ideas.



Hidden Components

Often there will be unstated components in an argument that are crucial to the argument's structure. For instance, look back to the first argument on this page:

I think I should buy this used Toyota Corolla. Why? They're practically giving it away.

At the time, I suggested that it was a single support argument:

P1: They're practically giving it away.

MC: I think I should buy this used Toyota Corolla.


But is it? It is enough to say that one ought to buy a car just because they're practically giving it away? What if you really don't need a car at all, for any price? What if you need a car, but the one that's being "given away" is just junk, and you don't want it? The success of the argument depends on a hidden premise:

P1: They're practically giving it away.

HP2: I need (or would like to have) the car

MC: I think I should buy this used Toyota Corolla.


There can also be
hidden conclusions. Sometimes people think the conclusion is so obvious that it doesn't need stating, or it is implied in some other way:

This Corolla is fast, cheap, and just what you need. What more do you want?

P1: This Corolla is fast.

P2: This Corolla is cheap.

P3: You need a car.

HMC: You should buy this Corolla.


Often, hidden components are used when someone wants to draw our attention away from a deficiency in an argument, or from a presupposition that they don't want us to examine too closely. It's important, therefore, to be aware of the hidden components in the arguments of others, and to minimize them in your own work.