#18 - Certain changes in North American residential

[Jeff Wren]

Hi albert,

You're right that the word "mainly" in the stimulus does allow for the idea that there may have been other factors that contributed to the changes in North American residential architecture, but the increased availability and affordability of air conditioning is stated to be the primary cause.

Generally, you'll weaken a partial-cause argument in the same five ways as a standard casual argument, except that you should be wary of answers that seem to be offering an alternate cause (which is generally a great way to weaken a normal causal argument). For an answer to really weaken this argument using an alternate cause, it would need to state or imply that the alternate cause may have been the primary cause, not just a contributing factor, because just identifying a possible contributing factor would be consistent with the conclusion and therefore not weaken the argument.

For example, many people felt that Answer E was offering an alternate cause for the design changes. Even if this were true, we don't know that this would have been the main cause; this could have been an additional cause even though the air conditioning was still the primary cause. (Also, as Adam mentioned in an earlier post, the thermal-insulating technology could have been an effect of designing thin walls rather than the cause. In other words, the architects may have decided to make the walls thin because of air conditioning, and then realized that they would need thermal-insulating to keep the heat in with the thin walls.)

The other four methods still work well even with partial-cause arguments, and Answer C, which shows the effect occurring without the cause, still weakens the claim that air conditioning was the primary cause of the design changes.

[ZackSaiz]

So I'm also between answers C and E. The partial (but primary cause) argument I think is the best one for eliminating choice E. Yes, without a doubt new thermal-insulation would be a potential alternate cause for a change in residential architecture. If anything, it seems more similar to thick walls and high ceilings in that it is just keeping what is inside the same temperature (not changing the temperature like AC would). Though that is probably irrelevant, I don't think it is an outside assumption to assume thermal insulation would act in a way that would make thin walls and low ceilings possible. This is a VERY tempting answer and what I did answer, twice. Any argument that says (as mentioned on this thread), that thermal insulation was "applied" in house building, and was a part of the house, but didn't actually work to insulate seems to overlook common sense. If applied, something (the thermal insulation) logically did its function unless we have reason to think otherwise. However, one COULD argue that it was only applied in house building, but wasn't there as part of the final product. To me that would make sense.

Am I knit-picking language? Yes, but that is exactly what the LSAT asks us to do. Now I am going to do the same thing on answer C.

For answer choice C, the argument, as far as this thread goes, is that the presence (and the prevalence) of low ceilings and thin walls are NOT what traditionally kept residents cool (per the stimulus), but the thin walls and low ceilings were already prevalent so there was no certain changes with regard to thick walls and thin walls. If there was no change in residential architecture, Air Conditioning (AC) cannot be primarily responsible for a change that never happened. Sure, but there is an assumption being made that because something is prevalent beforehand that changes can't happen (due to AC) after the fact, especially in the direction that would make that something (low ceilings and thin walls) more prevalent. But who is to say that? The same way that new thermal insulation being "applied" in house making doesn't guarantee that it is a part of the final product is the same way that being prevalent before doesn't mean that something being prevalent before doesn't mean that it can't become WAY MORE prevalent.

For example, iPhones were prevalent in 2010, but now in 2025 they are way more prevalent. Everybody would agree that a change to the North American mobile phone landscape has happened since then. Can iPhones not be primarily responsible because they were already prevalent in 2010? That is a bad argument. This is hinging on the word prevalent, which has different interpretations based on context (and sometimes can be subjective). Am I knit picking again, YES, but I want to get a question like this right. Prevalent doesn't suggest a majority (also mentioned on this thread) simply that something is widespread. If police officers were shot on 30% of days or in 30% of cities would police officer shootings be prevalent? Yes. Maybe, these low ceiling thin wall houses existed in some prevalent amount before a demand for air conditioning, but because of air conditioning, became 95% of new houses being sold and 75% of residential architecture. Therefore, I can't agree that answer choice "C" weakens the statement that AC was responsible for a change in residential architecture because it doesn't actually preclude the change that would weaken it. If answer choice C mentioned something about the prevalence remaining constant, then I could 100% get behind it.

But, I need to think of what so the LSAT makers want me to answer... Okay, so in a partial/main causal argument a simple alternative cause actually isn't a great weakener and shouldn't be my answer unless there is something in that answer choice to make me believe it would me the MAIN cause. That is absent in answer choice E, which leaves C as the best answer (though clearly, I don't think it is a very good answer). Is that good reasoning?

[ZackSaiz]

I didn't use preclude correctly on that second to last paragraph, but you get what I was saying. Answer choice C doesn't necessitate the situation that would in fact weaken the argument in the stimulus.