argument50(超越自我小组)第十六次作业

zugurrrUID: 2482827

argument50
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."



The arguer gets the conclusion that the water in Earth's oceans must have originated from comets, based on an assumption that water on the space rocks which form the earth have vapored and gone off into space. And other evidence is the comets which have struck earth leaving the water on earth. But there are several fallacies about the arguments

First, if the collisions of space rocks have still happened after the earth approached its size and the gravitation became strong enough to hold gases, then the water of the earth should come from the space rocks. As the common sense, the proportion of the collision between the earth and space rocks is much higher than with the comets. And there are no evidence to show that in the space rocks are no water. So without explanation of this mostly like possibility, it is unwarranted to conclude that water in earth originated from comets.

Second, the arguer failed to explain the correlation of the comets largely are made up of frozen water amounts to the causal relationship to the Earth water. If the comets have been the reason of the ocean, then such collisions between so many comets with earth would unavoidably cause the changes of the solidified surface of Earth, but unfortunately, the modern scientists have found so many evidences. Meanwhile to make sure the plenty of Earth water, there should be a large number of comets which have collided with Earth. However, on one hand, the number of comets which traveled through the solar system is limited, even the whole galaxy is not too many. On the other hand, the comets are all on the too fast speed to turn their direction directly to the Earth by the gravitation from the planet, especially the Earth at the certain position near the Jupiter in the solar system, the proportion of such collision is much lower.

Third, the argument has neglected alternative facts about the Earth water. There may be some chemical reaction, which between the elements on the Earth under the special conditions during some stages of the Earth forming. Without excluding some other possible reasons, it is vague to prove the Earth water came from the comets.

In sum, before the arguer gets the conclusion that the Earth water came from the comets, he must provide evidence to exclude other possible events. To strengthen the argument, he also need to prove the possibility of the such large number of comets, and provide the evidences of the existence of so many such collisions.