Read the sample student claim and counterclaim.

Claim: Although many people argue that medical testing on animals is a violation of animal rights, the benefits it yields for society far outweigh any argument that can be made.

Counterclaim: There are safer and more accurate ways to test medications without using animals.

What evidence would most weaken the counterclaim presented here?

The physiologies of humans and some animals are very similar, so the reactions of these creatures to certain medications are the most reliable guide to the possible reactions of human patients.
Scientists are more easily able to control an animal’s environment, such as diet and temperature, than they are that of humans, which makes the tests far more reliable than alternative methods.
Animals have emotions and can feel pain much as humans do, which is why I feel that it is cruel to subject these vulnerable creatures to unfair tests that we are unwilling to conduct on humans.
If we ban testing on animals for medical research that could save lives, then it also must be made illegal to hunt and kill animals simply because we would like to include meat in our daily diets.