What can science do?

Many species of whales have been hunted to the brink of extinction.  Many people think that we do not have the right to kill whales and that all whaling should cease.  On the other hand, in many cultures whales have been hunted for centuries and still have great cultural importance.  People from cultures argue that limited whaling should be allowed to continue.  What is the role that science can play in deciding who is right? What questions cannot be answered by science?