Question

The argument following was first given by people who sell shark cartilage as a cancer treatment: No one has ever discovered a shark with cancer, so sharks do not get cancer. Which of the following responses is the best criticism of the form (reliability or strength) of that argument?

A)	Because the authors of the argument are an interested party, the argument is subject to a legitimate ad hominem criticism.

B)	There are in fact many discoveries of sharks with cancer. A simple google search will reveal as much.

C)	Because of their habitat and ferocity study of live sharks is limited. Furthermore, because of their divergent goals, those who routinely capture sharks do not search them for tumors. So, even if sharks did get cancer we wouldn’t expect to know about it.

D)	Even if sharks don’t get cancer, that provides no evidence that ingesting shark cartilage is therapeutic as a cancer treatment.

Answer 1

Even if sharks don’t get cancer, that provides no evidence that ingesting shark cartilage is therapeutic as a cancer treatment is the best criticism of the form (reliability or strength) of that argument as cartilage has anti antigenic properties--i.e., it inhibits the development of blood vessels, which are crucial to the growth of cancerous tumors--and since shark skeletons are made of cartilage, it follows (albeit somewhat loosely) that they can't get cancer.