Traditionally when it comes to enviromental pollution, the general philosophy was that ‘the polluter pays’. A factory polluting the air or water should pay for the damages that are caused. In a much simpler case, if you build a house next to me and you don’t like the smell of livestock waste coming from my property, the traditional philosphy would hold that you could have the government stop my operation.
The insight that Coase brought was 1) yes it is true that my operation is harming you via air pollution. 2) however, in stopping me via government or legal intervention ( or taxing my waste production) you are harming me.
Coase says that the issue is that nonone owns the air that sourrounds my livestock operation and your home. There then follows a dispute over how the air should be used- to absorb livestock odor, or to provide a scent free atmosphere in your back yard. Whenever the cost of one’s behavior is not factored into a price at which a choice can be valued, I can harm you without compensating you for it. ( i.e. an externality exists)
However, if I own rights to the air, then I can choose to pollute the air. If you own rights to the air, then you can prevent me from polluting it. If noone owns the air, then it is first come first served or winner takes all.
That is not the end of the story though. What Coase emphasizes is that if I own the rights to pollute, you can pay me to limit my pollution i.e. buy those rights from me. I can then use the proceeds to alter my livestock nutrition, genetics, and management to reduce the odor my operation is causing. On the other hand, if you own the rights to pollute I can purchase those rights from you, or invest in technology that will allow me to continue my operation without violating your rights. I will do which ever is most optimal. This can be accomplished without major goevernemnt regulation, or the arbitrary imposition of a tax.
The assignment of property rights and the potential for bargaining results in behavior that is changed or altered to account for the negative impact our choices have on others. This is the essence of what is known as the ‘Coase Theorem”