Tragedy of the Commons and Externalities

Definitions:
Tragedy of the commons- Describes the phenomenon of overuse of resources held in common (i.e. by "public" or government) that occurs because the failure to adequately define property rights means that no one has an incentive to conserve or maintain the resource and all have an incentive to use the resource before others do.
Externalitlies-The cost and/or benefits that are not internalized by the processes of production and exchange, and which therefore spill over onto third parties. Externalities may be positive or negative.

Will a capitalistic Free-Market Economy Always Optimally Allocate Resources?
Personally I don't know how I feel about this question. I feel that the free market should always optimally allocate resources but I don't know if they will. As humans we feel that everyone owns the natural resources and who are they to take that away from us. This is a very difficult question to answer and feel that I don't have one single answer for it. I feel that at this time the capitalistic free-market economy is doing an alright job at optimally allocating resources but when the resources start to diminish I have no idea what will happen. You never know what the future will bring so to be honest I can't tell you.