Demand of flasts in a particular society is rising causing rise in their prices. On the other hand law of demand states inverse relation between price and demand of a commodity. Why is this contradiction ? Do economists say inconsistent things ?

Explanation

There is no contradiction, also economists do not say inconsistent things about relation between price and demand of a commodity. We need to understand the cause and effect relation between the two.
If demand of the commodity rises, it will cause price rise due to competition among buyers.
If price rises, it will cause fall in demand of the commodity (law of demand).