Liberty

Here are a few more thoughts on unalienable rights. In his 1748 book The Spirit of the Laws (which greatly influenced the American Founders), Montesquieu wrote:

There is no word that admits of more various significations, and has made more different impressions on the human mind, than that of liberty.

Montesquieu goes on to distinguish two primary senses of what he calls political liberty:

1. Constitutional liberty arises from well-defined limits on the functions of government and on the people who exercise those functions (e.g., through the separation of powers across the legislative, executive, and judicial branches).
2. Personal liberty is the individual’s sense of safety and tranquility in society, especially security against arbitrary attacks and accusations under the law (e.g., prosecution for what today we would call thought crimes).

Constitutional liberty and personal liberty are two sides of the same coin, i.e., of political liberty; together, they protect and reinforce what he calls philosophical liberty, i.e., the free exercise of the will in thought and action.

At least, such is my reading. Even this brief overview suggests that liberty provides a connecting link between life and the pursuit of happiness, because life is activity (as Aristotle said) and the pursuit of happiness depends on freedom of thought and action.