There is no doubt that discussion and negotiations are the best ways to resolve any conflict..
However being aware of fundamental reasons of the differences helps in understanding each other;
** Different departments speak/understand different language
(For example Finance knows numbers only and is unable understand the operations lanuguage till the time it sees the hidden numbers behind quantam savings through the timely availability of inventory. On the same note opearation needs to understand the hidden cost of carrying that inventory in terms interest, handling, obsolesence etc.. )