Argument50 0710G同主题写作第四期 请指教

samurai023UID：2361605

50.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."
当地球在太空岩石的撞击作用下形成的时候，撞击产生的热量和行星越来越大的重力能量使整个行星融化，甚至包括表面。当时存在的任何水分都会蒸发并消失在太空。然而，当行星接近现在的大小的时候，它的重力强到了足以保持其周围的气体和水蒸气来形成大气层。由于彗星主要是由冻结的水和气体组成的冰，撞击地球的彗星将会蒸发。产生的水蒸气将被留在大气层，最终以降雨的形式落在地球已冷却而且坚硬的表面。因此，地球海洋的水分一定是来自彗星。

提纲：
1没有足够的信息表明在地球接近现在大小的之后，有彗星撞击地球。如果此后一直没有那么，则不能认为地球上的海水来自于彗星。即使有，论者也没有提供彗星所含水分于地球目前所含水分的比例关系，如果彗星相对比地球小很多，而且撞击的次数不多，那么大部分地球上的水分也不是来源于彗星。
2论证有前后不一致之处，论者之处地球形成时收到太空岩石的撞击产生的热量会使水分蒸发并消失在太空中，而之后并没有说明彗星撞击地球之后就不会发生着这种情况。
3论断太武断，忽略了其他的可能。但实际上还有其他很多途径能给地球带来水，比如地球上元素的化学变化等等

The arguer endeavors to convince us the statement that the water in Earth's oceans must have originated from comets. Although seems to be well-founded at the first glance, the argument can barely withstand any scientific scrutiny for its several flaws rendered as follows.

As the threshold, the argument lacks a substantial precondition to draw such a strong conclusion. Firstly, we are not informed that there are comets striking earth after it had approached its current size, in other words, its gravitation became strong enough to hold gases and water vapor around it as an atmosphere. If not, it's impossible that it is the comets brought the earth the water in its oceans. Even if there are indeed some collisions between comets and the earth, it is also presumptuous to affirm the statement just according to the mentioned evidences. Maybe the water contained in a comet is just a little compared to that in Earth's oceans, and the number of collisions is inadequate, thus it is obvious that mostly water in the Earth's oceans is not originated from comets. Without additional information to eliminate such possibilities, I can not accept the arguer's conclusion.

Besides the deficiencies, there are still some fallacies in the process of deduction. There is an inconsistency in this argument. The arguer mentions that the heat from the collisions of the space rocks made any water present evaporated and gone off into the space, beyond the influence of the gravitation, while he or she claims that the water vapor generated by the ones of the comets would have been retained in the atmosphere other than get rid of gravitation, without providing us a sufficient reason to explain this contradiction, a dilemma attenuate the persuasion of this argument.

Moreover, the arguer commits a fallacy of neglecting other relevant possibilities. A myriad of other factors might just as likely be the cause of the formation of the water on the Earth. For instance, the chemical transformations all around the Earth, which are happening in every single minute, may generate enough water to cover much of the surface of the Earth and to afford appropriate condition for the naissance of lives, which in turn accelerate the process of water formation by photosynthesis.

In sum, in order to enhance the persuasion, additional records of the collisions between comets and the Earth should be provided and further investigations are needed to exclude other possible ways for water formation.

[ 本帖最后由 samurai023 于 2007-8-6 15:23 编辑 ]