For

Knowledge about the past is useful to complete our knowledge of the world we live in. By knowing the secrets of the past we can find meaning in our present lives. It is widely known that the past shapes the present, so if we can discover our past we can learn from the mistakes committed by our ancestors to improve our present life. We can also draw inspiration from the selfless deeds of rulers, martyrs, patriots, etc. to benefit the society and extend our helping hand to the needy.

Against

Some things from the past are best left unknown or undiscovered. There are possibilities that forbidden knowledge or secrets could lead to a chain of untold, unexpected events that could disturb our current peace. Past controversies, conflicts could bring up buried hatred, resentment, and stir up fresh trouble.