An appeal to tradition essentially makes two assumptions that are not necessarily true:
The old way of thinking was proven correct when introduced, i.e. since the old way of thinking was prevalent, it was necessarily correct.
In actuality this may be false—the tradition might be entirely based on incorrect grounds.
The past justifications for the tradition are still valid at present.
In actuality, the circumstances may have changed; this assumption may also therefore be untrue.
The opposite of an appeal to tradition is an appeal to novelty, claiming something is good because it is new.
Appeal to tradition - Wikipedia, the free encyclopedia