Argument50 0710G同主题写作第四期by abc021900

abc021900UID: 2369431

From a draft textbook manuscript submitted to a publisher. "As Earth was being formed out of the collision of space rocks, the heat from those collisions and from the increasing gravitational energy of the planet made the entire planet molten, even the surface. Any water present would have evaporated and gone off into space. As the planet approached its current size, however, its gravitation became strong enough to hold gases and water vapor around it as an atmosphere. Because comets are largely ice made up of frozen water and gases, a comet striking Earth then would have vaporized. The resulting water vapor would have been retained in the atmosphere, eventually falling as rain on the cooled and solidified surface of Earth. Therefore, the water in Earth's oceans must have originated from comets."


In the argument, the author concludes that the water in Earth’s oceans must have originated form comets. Close scrutiny on the evidence, however, reveals that it lends little credible support to the conclusion.

To begin with, the author unfairly assumes that comet had hit the earth. However the author does not provide evidence to support is. Without such evidence, it is highly possible that no comet hit the earth, thus the author’s conclusion is unacceptable.

Furthermore, even if comet has ever stroke the earth, we still cannot say that the water in Earth’s oceans must have originated form comets for several reasons. First, when did the comet hit the earth? If it was at the time when the earth had not approached its current size, them even if the comet hit the earth, it is unlikely that water of the comet will retain in the earth, not to mention water form the comet form the ocean. Second, even if there were comets hit the earth after the formation of the earth, the author’s conclusion is premature. Common sense is that the chance of two celestial body strike each other is rare, if any. So it’s possible that the water from the comet is not enough to form the ocean. Third, even if I concede that there were enough comet stoke the earth, whether the water of comets would become the water in ocean. As some of the water of comets may become vapor never water on the ground. If any of he scenario is truly, the author’s conclusion will be unconvincing.

Moreover, the author overlooks other possibility that the water in oceans may come from. When I was in the middle school, I was told that hydrogen and oxygen together can generate water. So it is possible that the water in ocean was created by such chemical reaction. It is also possible that other celestial body other than comet hit the earth and brings water with him. Or perhaps after the formation of earth to its full size, water outside of earth can be attracted due to the strong gravitation of earth. Without ruling out such possibility, then I cannot accept the author’s conclusion that the water in Earth's oceans must have originated from comets.   

In sum, the argument is logically flawed, to bolster it the author has to provide evidence that comets ever hit the earth, and the water of comets is enough to generate the ocean. To better assess the argument the author should also rule out other possibilities for the origination of the ocean.

[ 本帖最后由 abc021900 于 2007-8-6 23:07 编辑 ]

doris_gxcUID: 2370933

In the argument, the author concludes that the water in Earth’s oceans must have originated form comets. Close scrutiny on the evidence, however, reveals that it lends little credible support to the conclusion.

To begin with, the author unfairly assumes that comet had hit the earth. However the author does not provide evidence to support it. Without such evidence, it is highly possible that no comet hit the earth, thus the author’s conclusion is unacceptable.

Furthermore, even if comet has ever stroke the earth, we still cannot say that the water in Earth’s oceans must have originated from comets for several reasons. （有点突兀，可以加一句Several question should be asked.）First, when did the comet hit the earth? If it was at the time when the earth had not approached its current size, them even if the comet hit the earth, it is unlikely that water of the comet will retain（be retained） in the earth, not to mention water from the comet form the ocean. Second, even if there were comets hit the earth after the formation of the earth, the author’s conclusion is premature. Common sense is that the chance of two celestial body strike each other is rare, if any. So it’s possible that the water from the comet is not enough to form the ocean. (这里有个assumption是说多次撞才够？)Third, even if I concede that there were enough comet stoke the earth, whether the water of comets would become the water in ocean. As some of the water of comets may become vapor never water on the ground. If any of he scenario is truly, the author’s conclusion will be unconvincing.

Moreover, the author overlooks other possibility that the water in oceans may come from. When I was in the middle school, I was told that hydrogen and oxygen together can generate water. So it is possible that the water in ocean was created by such chemical reaction. It is also possible that other celestial body other than comet hit the earth and brings water with him. Or perhaps after the formation of earth to its full size, water outside of earth can be attracted due to the strong gravitation of earth. Without ruling out such possibility, then I cannot accept the author’s conclusion that the water in Earth's oceans must have originated from comets.   (good!)

In sum, the argument is logically flawed, to bolster it the author has to provide evidence that comets ever hit the earth, and the water of comets is enough to generate the ocean. To better assess the argument the author should also rule out other possibilities for the origination of the ocean.

很欣赏开头的简洁和结尾的精炼！