What exactly is an "essence"? Philosophers talk about it all the time, yet they can't seem to agree on what it is. Aristotle's essences were essentially little ghosts that live inside things. Plato's essences were perfect forms in a supernatural realm, somehow reflected in our own. Hegel's essence is "Being coming into mediation with itself through the negativity of itself"... whatever the hell that is.
What is common among all these extremely different ideas? Why do authorsĀ to give them the same name?
The fact is: we started identifying and grouping existents before we fully understood the process of identifying and grouping existents. Once we became self-aware enough, we had to explain what exactly it is we're doing - what that process consists of. "Essence" thus became the property of the object that makes us call it what it is, whatever one's theory of knowledge makes that out to be.
Understanding this is key to understanding the different ways in which Ayn Rand and Jean-Paul Sartre use the word.
Sartre conceptualizes the essence of a thing as its existential purpose, defined by its creator. According to him, we call a paper-cutter a paper-cutter because whoever made it, made it with the purpose of cutting paper in mind. Choice is the alpha and the omega - a thing is the intention behind it, not an independent existent. The purpose of such an epistemology is thus "balancing out" people's subjective opinions, not identifying reality.
He argues that human beings have no creator, so they are not born with an essence. Since a creator's will is the standard of one's essence, we are left without an essence - and this lack of essence is what makes us free. Our actions inescapably define us - a man who steals makes himself a thief - but there isn't a standard one must follow, because one wasn't created with a purpose. This is the reasoning behind Sartre's notion that we are "condemned to be free" - we are free, unfortunately, because we lack purpose and essence.
Rand has no such interest for people's subjective opinions. The purpose of her epistemology is to identify the facts of reality to the best of one's ability. As such, her essence is not a property of concrete objects, but of concepts. The essence of a concept is the fundamental characteristic of its units that distinguishes them from other existents in a specific context.
The essence of a human being is not a purpose bestowed upon him by a creator. It is that which makes him different from other existents - his rational, volitional mind. Freedom is the ability to choose one's own purpose - not because one wasn't bestowed upon us, but because one cannot be bestowed upon us. The very aspect that differentiates us from other things - which exists regardless of our subjective opinions and wishes - also entails the need to choose our own path in life.
479.266 SRY