Argument50 请大家狂改

charliesjackUID: 2338862

In this argument, the author draws his conclusion that the water in Earth's oceans must have originated from comets. To substantiate his conclusion, the author mentions the truth that comets are largely made up of frozen water. The author also provides some information about the formation of Earth atmosphere and other details. Although evidences the author provides seem to be impressive, they are too limit in scope to lead to the conclusion soundly.

One of the threshold problems of this argument is that the author mistakes the concept of comets for space rocks, which include a myriad kind of space matter like comets. As it is states in the argument, Earth was formed out of the collision of space rocks. It is equally possible that another or some other kind of space rocks, which may also contain quantity of water, plays a more important role in the origination of Earth's oceans. Without ruling out other possible explanations, the author's assertion that the water in Earth's ocean originated form comets is unfair.

On the other hand, the author fails to provide any information about during which period of time the collisions of comets to Earth happened. As the author indicates in the argument, at the early stage of time, the Earth as a whole is molten and any water will be evaporated and gone off into the space. It is as likely that most comets' collision with earth taken place at this period of time, and the water contained by the comets gone off into the space again. So, if this scenario is the truth, the author's assertion will be seriously undermined.

What's more, the author assumes obviously that the water of comets mostly become the ocean water of the earth. Even it is true that comets collide with Earth frequently and provide large quantity of water to Earth, the author still can not convince me that the water were used to form ocean. It is entirely possible that this amount of water were used to form the material of the earth, that is to say, in form of synthesis rather than exist freely as ocean. Without eliminating this and other possibilities, the argument's conclusion is still unfounded.

In sum, based on the evidences provided by the argument, we can hardly come to the conclusion that the water in Earth's oceans have originated from comets. To strengthen the argument, the author has to rule out other possible matter which can also provide earth with water. The author also has to prove that the collision of comets with Earth mostly happened after the gravitation of Earth being strong enough to hold vapor around it.

[ 本帖最后由 charliesjack 于 2007-8-7 20:01 编辑 ]