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 reality, 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 reality, the circumstances may have changed; this assumption may also therefore be untrue. An appeal to tradition is only a fallacious argument in itself if the argument is not developed further, for example by pointing out that the widespread acceptance of the practice means that there would be significant implications/disruption/cost involved in abandoning the tradition. For example, arguing that the QWERTY keyboard layout should be retained "because it is traditional" would be fallacious unless the further argument is made that, being traditional, QWERTY is familiar to most current keyboard users who would need retraining if any change were made. (The further development may introduce other fallacies.)
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 reality, 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 reality, the circumstances may have changed; this assumption may also therefore have become untrue. An appeal to tradition is only a fallacious argument in itself if the argument is not developed further, for example by pointing out that the widespread acceptance of the practice means that there would be significant implications/disruption/cost involved in abandoning the tradition. For example, arguing that the QWERTY keyboard layout should be retained "because it is traditional" would be fallacious unless the further argument is made that, being traditional, QWERTY is familiar to most current keyboard users who would need retraining if any change were made. (The further development may introduce other fallacies.)
R
be
have become