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"the real reason for the Yosemite decline" - my argument essay

jade 2 / 7  
Mar 25, 2010   #1
who can spare a few mins to help me grade this essay? my GRE analytical writing exam is on the horizon, 16 days to go, a little depressed... I have no logic T_T

Argument 150
The following is a letter to the editor of an environmental magazine.
"The decline in the numbers of amphibians worldwide clearly indicates the
global pollution of water and air. Two studies of amphibians in Yosemite National Park in California confirm my conclusion. In 1915 there were seven species of amphibians in the park, and there were abundant numbers of each species. However, in 1992 there were only four species of amphibians observed in the park, and the numbers of each species were drastically reduced. The decline in Yosemite has been blamed on the introduction of trout into the park's waters, which began in 1920 (trout are known to eat amphibian eggs). But the introduction of trout cannot be the real reason for the Yosemite decline because it does not explain the worldwide decline."

This argument looks tenable at first glimpse, but further scrutiny raises several fallacies.
First of all, the author maintains that according to a survey conducted in Yosemite Natural Park, where both the number and the species of amphibians fall drastically from 1915 to 1992, the disappearing species and lost numbers of amphibians are attributed to pollution. But the premise that there are lost species remains weak, the unobserved 3 species of amphibians may be still exist, they just migrate to somewhere else or simply doggo in the mountainous area in the park.

Even if the decrease of the number and species was a true fact, it does not directly leads to the conclusion that the air and water in the park are polluted. Here the author commits a circular reasoning mistake. It is not the decreased number of amphibians that indicates pollution, but pollution foreshadows the loss of animals. To start with, the argument offers nothing in detail about the environmental situation of the park. To convince me that the park's water and air are contaminated, I need to know the exact numbers of hard precise official evaluation of its environment. For example, specific analysis of the park's water quality, and its air quality. Only when the numbers indicates a slash of environmental statistics will it convince me that the park is polluted.

Nevertheless, even though it is true that Yosemite's water and air quality turns out be questionable, it does necessarily present itself as the sole contribution to the extinction of species. As mentioned by the author, there is another factor which potentially pushes those amphibians into death, trouts. The park has been introducing trouts, which feeds on the eggs of amphibians, for more than 70 years, the large existence of trouts pose a impressive threat on the survival of amphibians. Probably, They may be eaten by trouts, thus comes the decline of amphibian numbers. Or, the lost variety of amphibians simply has nothing to do with pollution or trouts, the reason could be that they succumbed to natural selection for they fail to adapt themselves to the changing climate. It is nature, instead of others, that takes their course. Also, the drop of number might be an outcome of illegal excessive hunting. Without ruling out these scenarios, the argument could not persuade me to believe that the water and air pollution are solely responsible for the deterioration of amphibians.

Finally, the author falsely expands the analogy to conclude that amphibians are extinguishing globally due to the same reason- water and air pollution in Yosemite park, an unsubstantiated premise in so far.

In final conclusion, the argument is weakened by the failure to establish the deduction that the polluted environment results the decline of amphibians in Yosemite park, and it appears to be unreasonable to hastily generalize that the worldwide tendency precisely tally with Yosemite park.
EF_Kevin 8 / 13,321 129  
Mar 26, 2010   #2
Use a semi-colon, or it will be a run-on sentence:
But the premise that there are lost species remains weak; the unobserved three species of amphibians may be still exist, they just migrate to somewhere else or simply doggo in the mountainous area in the park.

the argument offers nothing in detail about the environmental situation of the park. --- excellent point!!

This is a great analysis. You showed that the speaker actually is not observing anything about global conditions, but instead is simply observing something about the park. What is the logical fallacy called when you look at one example and assume everything else to be like it?

Anyway, coming full circle, you can acknowledge that the loss of those species is indeed evidence to support the argument that pollution is severe. It does not prove the argument by itself, but it is still important evidence to support arguments that pollution is severe.
OP jade 2 / 7  
Mar 27, 2010   #3
Thanks a lot, Kevin!
About the semicolon, yeah, I 've known the usage for some time, but it's just a little bit hard for me to remember when to use it. I will pay attention to that:p or the potential outcome is unaffordable: run-on sentence:p

Pardon me, what did you mean by the last sentence in yr comment? Are you saying that I should not doubt the loss of the 3 kinds of amphibians? I thought I was intended to undermine the effectiveness of the conclusion that the environment is polluted...
EF_Kevin 8 / 13,321 129  
Mar 28, 2010   #4
About semi-colons:
They really work a lot like periods; I use one instead of a period when two sentences are closely related to one another. Google this: use of semi-colons

About my last comment:
I think the clearest understanding of this arguments problem is that the speaker is saying, "Because species are missing from the park, pollution is severe everywhere." At best, this argument shows that pollution is severe at the park, but as you explained, even that is not necessarily the reason for the disappearance of the species.

So, in order to use excellent reasoning, you can acknowledge that the disappearance of species at the park is one piece of evidence to support the idea that pollution is severe in the world, but it is a logical fallacy to infer something about global pollution based only on this observation about the park.

It's like if I said, "Jade wrote an excellent essay, so EssayForum members tend to write excellent essays." In actuality, the fact that Jade wrote an excellent essay does support the argument that EF members write good essays, but it is poor reasoning to assume that a generalization about all essay forum members (or worldwide pollution) can be inferred from an observation of Jade (or Yosemite Park).

So, the point is that you can acknowledge that this is indeed evidence to support the argument that pollution is severe, if it is presented with lots of other evidence, but it alone is not sufficient to draw a conclusion.
OP jade 2 / 7  
Mar 30, 2010   #5
EXCELLENT! Clearer than my guilding book.
I Got it! thanx so much, I'll rewrite it later. :P

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