I would say that one assumption is the superiority of Europeans over Africans: their belief that somehow they had the right to enslave other people.
This could be connected to their racism (they thought the same of native Americans and there was a discussion whether native Americans have souls) or religious feeling of superiority ("pagans are not the same as Christians"...)
He/she will say that both glasses held the same amount of liquid. By the concrete operational stage, the child has developed the ability to understand conservation, and knows that just because the shape or appearance changed doesn't mean the quantity of liquid changed.
Answer:
It is vitally important in a democracy that individual judges and the judiciary as a whole are impartial and independent of all external pressures and of each other so that those who appear before them and the wider public can have confidence that their cases will be decided fairly and in accordance with the law.