29The following report appeared in an archaeology journal.
"The discovery of distinctively shaped ceramic pots at various prehistoric sites scattered over a wide area has led archaeologists to ask how the pots were spread. Some believe the pot makers migrated to the various sites and carried the pots along with them; others believe the pots were spread by trade and their makers remained in one place. Now, analysis of the bones of prehistoric human skeletons can settle the debate: high levels of a certain metallic element contained in various foods are strongly associated with people who migrated to a new place after childhood. Many of the bones found near the pots at a few sites showed high levels of the metallic element. Therefore, it must be that the pots were spread by migration, not trade."
The argument involves several facets that are questionable though it appeals logical at first glance. First, the presumption this argument based on is untenable-that is, those bones found at the same site belong to those who was living together from their childhood. Besides, some evidence the arguer shows is not so persuasive that cannot give fiber to his argument. The arguer also make a fallacy in drawing the conclusion presumptuously without taking into account some substitute explanations. I would like to analyze each of these omissions in turn.
As a threshold matter, the argument stands on an invalid precondition that those bones found at a certain place belong to people who migrate from the same area to here after childhood. Though high level of the metallic element was discovered near the pots at a few sites, it cannot show us that the metallic element only exists in a certain area and we may not find it anywhere else. If we are told the metallic element is common that it can be seen in a lot of places, then we can judge those bones pertain to people from different places in a large extent, which is contrary to the assumption.
Even premise the above prerequisite is realizable, it only explain the pots near those bones were spread by migration while how the rest pots were spread is still open to question. It is entirely possible that they were circulated by journey, hunting, trading or even wars and the like. So the arguer has not helped us to eliminate so many conjectures by giving more evidence.
Yet another problem with the argument is making the conclusion too prematurely and imprudently. Even if the bones belong to people who were once living together, we are not sure those people appear in different places due to migration. The arguer attributes this to migration rather than trade arbitrarily, neglecting to count out other possible factors which can inspire the spreading of pots.
Overall, the reasoning behind the conclusion that pots were spread by migrating seems persuasive as presented above. To make it more convincing, the arguer would have to provide concrete evidence concerning that the metallic element merely lies in a certain place. To better evaluate the argument, we would need more information to eliminate other methods people used to circulate the pots.