Spinoza on the Metaphysics of Self-Interest

Implicit in being oneself is the commitment to oneself. One pursues one's life. One doesn't need a reason to pursue it. One pursues it, quite obsessively, because it's one's life. Who else's life is one supposed to pursue anyway?

There is an absurdity in even asking for a reason as to why we should care about ourselves. Identity itself explains the self-concern. We don't require any persuasion in taking a special interest in what will befall us. The persuasion we require is to take an interest in others as well. That's the business of ethics, and the business, too of [Spinoza's] The Ethics.

Spinoza tries to capture this fundamental fact -- that our commitment to ourselves is unlike the commitment to anything else, since it is tantamount to simply being oneself -- in his concept of conatus. Conatus is simply a thing's special commitment to itself....: "The endeavor, wherewith everything endeavors to persist in its own being, is nothing else but the actual essence of the thing in question."...

Spinoza has not yet begun, at this point in The Ethics, to make any ethical claims. What he's making, at this point in The Ethics, is a metaphysical statement, not an ethical one, trying to explain what makes an individual thing that individual thing that it is. 

--Rebecca Goldstein, Betraying Spinoza: The Renegade Jew Who Gave Us Modernity