Appeal to tradition

Appeal to tradition (also known as "argumentum ad antiquitatem", appeal to antiquity, or appeal to common practice) is a common fallacy.
In this fallacy, an idea is claimed to be right because it is the way it was often done in the past. The appeal takes the form of "this is right because we've always done it this way".
An example of appeal to tradition is, "drinking boiling hot water (and never cold water) is always healthy because Chinese people have done it for thousands of years."
An appeal to tradition essentially makes two mistakes:
In the case of drinking boiling water, traditional Chinese medicine claims that the health benefits come from re-balancing one's own qi, rather than the fact than un-boiled or un-chilled water may have dangerous germs in it.
The opposite of an appeal to tradition is an appeal to novelty, claiming something is good because it is "new".