Can i have a dog?

If you can be dedicated to the dog's care (daily walks, cleaning it's crap, feeding, bathing, play time, etc.), can afford all of the dog's needs (food, vet bills, dog sitter if you go away), and have the space for a dog, perhaps you can approach your parents with the idea that you will personally be responsible for the dog. Don't expect your parents to foot the cost though. Animals are expensive.

Nope, the universe will not allow it

Trust me, you should listen to your parents, dogs are awful in every way.