agency
When we think of the word "slavery," defined as a system of relations in which individuals are compelled to perform labor, it is reasonable to define the inverse as the absence of compulsion. The word most associated with such a situation is "freedom." Closely related but with a more political connotation is the word "liberty."
I want to propose that a more accurate descriptor for the state of affairs in which an individual is not compelled to perform labor against his will is "agency." To be a free agent means, literally, to be free to act according to one's will.
The question that must be raised regarding abstract inquiries about freedom and agency is, how does one know what he ought to do? By what criteria can our hypothetical free agent decide what is worth doing?
In a world that places individual liberty above almost all other values, it should come as no surprise that a tremendous number of people are very dissatisfied when the response to this question usually fits the contours of "well, whatever you want!" So dissatisfied, in fact, that levels of self-reported anxiety and depression have risen monotonically since the supposed triumph over the totalitarian regimes of the twentieth century. To a liberal mind, it may seem dubious or even offensive to consider the possibility that there might exist a causal relationship between these observations.
Freedom to do whatever you want does not necessarily translate to being in possession of agency. Agency, unlike liberty, assumes knowledge of what is worth doing, and from what one ought to abstain from pursuing. The early liberal thinkers of the 18th century understood that "liberty without limit is licentiousness; and licentiousness is the worst kind of tyranny; a tyranny of all." (Alexander Addison, Liberty of Speech, 1798)