Passage Summary: If an outside power steps in to give a group of people their independence, they probably won't stay free because they didn't learn the necessary skills and values through their own hard work.

Conclusion: Political communities that achieve self-determination through the intervention of an external force will likely fail to remain truly free.

Reasoning: The political virtues required to maintain freedom are most likely to develop when a people must struggle for their own freedom rather than having it handed to them.

Analysis: This argument relies on a causal principle linking the process of obtaining freedom to the ability to sustain it. The author assumes that the 'struggle' is a necessary condition for the development of 'political virtues.' To find the principle this conforms to, look for a statement that bridges the gap between the method of acquisition (internal vs. external) and the likelihood of success. We are essentially looking for a rule that says if you don't earn it yourself, you won't have what it takes to keep it.