Continuing through the June 2007 LSAT, we arrive at an argument about global warming. Please read the argument critically, then come back. This one feels a little different, huh? That's because the argument, for once, seems close to being reasonable--there's no glaring flaw. All we have here is a description of a phenomenon and then an explanation of that phenomenon. There aren't a lot of moving parts. Still, the argument is far from complete.
According to the scientist, it is a fact that the Earth's average annual temperature has increased by about 0.5 degrees Celsius over the last century. We can't argue with this part. But the scientist goes on to explain this fact with a claim about causality: The warming is primarily the result of the buildup of gases in the atmosphere, which blocks the outward flow of heat from the planet.
Uh-oh. That's a claim of causation.
The LSAT has a field day with Cause and Effect arguments--I've seen Logical Reasoning sections where almost one half of the questions had something to do with Cause and Effect. Here, we are asked to identify "evidence against" the Scientist's explanation. Before I look at the answer choices, I'm going to think about two main problems that commonly pop up with this type of reasoning:
1) Is it possible that the Effect actually caused the alleged Cause? An obvious example of this is "Rich people own Bentleys, so Bentley ownership causes one to be rich." Silly, right? That's obviously backward. Well, we need to see if that might be happening in the Scientist's argument. Here, the Effect was global warming, and the purported cause was a buildup of greenhouse gases. So ask yourself: Is it possible that the Scientist has it the wrong way around? What if the warming actually caused the buildup of the gases? If that were true, then wouldn't the Scientist look silly for claiming that the gases caused the warming?
2) Is it possible that some other Cause actually caused both the purported Cause and Effect? An obvious example of this is "Smokers make a lot of new friends outside bars, and they also get a lot of cancer. So making a lot of new friends outside bars causes you to get cancer." Silly, right? Clearly smoking is the underlying cause both of making friends outside bars AND getting cancer. There's no causal relationship between making friends and getting cancer. So ask yourself: Is it possible that the Scientist is ignoring some other factor? We can get creative here. What if, I don't know, radiation from Uranus was causing both the temperature increase and the buildup of atmospheric gases? If that were true, then wouldn't the Scientist look silly for claiming that the gases caused the warming? (I'm sure that "Uranus" is not going to appear in the correct answer. But something like this could be perfect.)
I don't think either of these predictions is guaranteed to be correct. But both of them appear over and over and over as correct answers on old LSATs, so I'd be dumb not to look out for them. Okay, here we go. Remember, we're looking for the answer choice that would make the Scientist's argument look stupid:
A) This doesn't matter. The cause of the gases themselves really isn't in question here. They could have been caused by industrial pollution, automobiles, cattle, who cares? If Answer A were true, the Scientist would say "So what? The gases still caused global warming." We're looking for an answer choice that leaves the Scientist no reasonable response... we want to shut him up for good.
B) Hmm. If this is true, then the Scientist's purported Cause happened after the Scientist's purported Effect. Hey Scientist, I have a question for you: How can the gases have caused global warming if the global warming happened first? ... Hello? ... Scientist? ...
I like this answer, because the Scientist really can't say anything in response. (Also, notice that it kinda fits with my first prediction, the possibility that the warming actually caused the gases, instead of the other way around.) This one is a keeper.
C) Huh? Who cares. If this were true, the Scientist would say something like "My argument had nothing to do with solar radiation, but I am unsurprised that solar radiation fluctuates slightly from year to year. This does nothing to change the relationship between a buildup of atmospheric gases and the resulting global warming." There's no way this can be the answer.
D) Again, I don't see how this is relevant. The Scientist would say "I am not surprised that volcanic dust reflects the Sun's radiation. This fact does nothing to change the relationship between a buildup of atmospheric gases and the resulting global warming."
E) This would actually strengthen the Scientist's argument, but we were looking for a weakener. If this were true, the Scientist would say "yes, yes... since the Earth has been warming over the past century, this fact confirms my hypothesis that a buildup of gases has been causing global warming." The answer that most weakens the Scientist's argument is B, so that's our answer.
Thanks for reading! I'll be back tomorrow with our first look at the wonderful world of Assumption Questions. (Sufficient Assumptions, to be precise.)