What is a right?
A right is a claim to something.
This claim imposes a duty on others.
There are two levels of rights
Take the "Right to life" when people talk about this, they can refer to two different things.
It is no accident that the words "right" as in a liberty and "right" as in correct or the opposite of wrong are one and the same word. It is because you have the responsibility to defend yourself that it is only "right" that you should have the "liberty" to keep and bear arms.
It is because you have the responsibility to feed, clothe, and shelter yourself and those in your charge (children, dependents, spouse) that it is only "right" that you should have the "liberty" to acquire, own, use, and dispose of the fruits of your labor. (aka property)
It is "right" that you have these "liberties" among others precisely because of your responsibilities, otherwise it would be impossible for you to fulfill them. Your "rights" exist because of your very nature which creates responsibilities for you. If they aren't YOUR responsibilities, then they must fall to someone else, and thus it would only be "right" for that individual to have whatever sovereignty necessary to carry out the responsibility to care for and defend you.
When we talk about rights, we are talking about ownership. If nothing was owned, then there would be no rights.
All things owned are property, therefore all rights are property rights. (Note that you own yourself).
If there was no government, there would be no legal rights, just unofficial property rights. Since there are governments, there is a framework for making these rights official. The governments role is to enforce these rights, so they legalise them. These are legal rights. For all intensive purposes as a political site we are referring to what rights get the backing legally.
You are comprised of two interdependent elements. Your body and your mind. Your body belongs to your mind, bodys cannot own things, just as rocks and other inanimate objects cannot own. Putting this another way , you own you. Someone may be able to control you, kidnap you, drug you,force you to do something, but that is control, not ownership.The thing about ownership is you have the right of control. You must give constent for another to have access to the item owned.If someone uses force to get control of the item owned, then consent has not been given, otherwise force will not have been necessary.We consider in society that forcing people to do things without their consent is wrong. Examples of this are what we call crimes, Rape, mutilation, murder, theft, slavery. All the worst aspects of society come from violation of consent.
Note: In the case where there is no rights above, the custodian owns those rights.
We are talking legal rights, and not natural rights
The strongest argument for why rights are needed, rights defend against utilitarianism.
http://www.bbc.co.uk/news/uk-politics-19879314 Right to self defence
http://kprudchenko.wordpress.com/2012/09/28/burlamaquis-perfect-and-imperfect-rights/ Perfect rights, and imperfect rights.