Final answer:
The purpose of the null hypothesis in hypothesis testing is to serve as a default position that is tested against the alternative hypothesis.
Step-by-step explanation:
The purpose of the null hypothesis in hypothesis testing is to serve as a default position that is tested against the alternative hypothesis. By assuming the null hypothesis, researchers can evaluate whether there is enough evidence to support the alternative hypothesis. It is important to note that hypothesis testing is based on probability laws, and we can only talk in terms of non-absolute certainties.