Self-determination is the idea of a positive freedom, a freedom for actions that we originate, and that actions are "up to us." Such acts constitute the essence of free will. This is Mortimer Adler's term, translating ideas from Aristotle and Thomas Aquinas. It was adopted also by Robert Kane for his theory of Ultimate Responsibility.
The technical terms Determination and Adequate determinism  have been proposed as preferable to determinism to describe actions that are adequately determined by an agent's current reasons, motives, and desires, as opposed to the strict predeterminism by a causal chain of events going back before the agent's birth.
In the first volume of his work The Idea of Freedom, Adler classifies all freedoms into three categories:
* The Circumstantial Freedom of Self-Realization * The Acquired Freedom of Self-Perfection * The Natural Freedom of Self-Determination
Self-realization is freedom from external coercion, political and economic freedom, etc. (See Self-determination in politics.) This is the "freedom of action" of compatibilist philosophers since Thomas Hobbes and David Hume. They argue that the will may be pre-determined by antecedent causes in an unbroken chain that goes back to the origin of the universe, but humans are free as long as they are not physically or mentally constrained.
Self-perfection is the idea from Plato to Kant that we are only free when our decisions are for reasons and we are not slaves to our passions (making moral choices rather than satisfying desires). This leads to the idea that free will and moral responsibility are inextricably linked. Some modern philosophers think that "freedom" refers to whatever conditions are involved in choosing or acting in such a way as to be morally responsible.
Self-determination covers the classic problem of free will: are our actions up to us, could we have done otherwise, are there alternative possibilities], or is everything simply part of a great determinism causal deterministic chain leading to a single possible future?
Adler defines the natural freedom of self-determination as that which is not either circumstantial or acquired.
A freedom that is natural is one which is
(i) inherent in all men,
(ii) regardless of the circumstances under which they live and
(iii) without regard to any state of mind or character which they may or may not acquire in the course of their lives. 
In his volume II of The Idea of Freedom," written a few years later, Adler revisits the idea of a natural freedom of self-determination. He explicitly includes alternative possibilities and the self as a cause so our actions are "up to us." His "uncaused self" decides from prior alternative possibilities.
Up To Us
The idea that at least some of our actions are self-determined and "up to us," that we can be the "authors of our own actions," and that they are not caused by external events is perhaps the most ancient concept of free will. Although the Romans had in Latin the same complex combination of free and will in their term (liberum arbitrium or libera voluntas) as there is in English, the Greeks had no such combination.
For the Greeks, and particularly for Aristotle, the term closest to the modern complex idea of free will was ἐφ ἡμῖν - "on us" or "depends on us." In the Nicomachean Ethics, Aristotle said,
εἰ δὲ ταῦτα φαίνεται καὶ μὴ ἔχομεν εἰς ἄλλας ἀρχὰς ἀναγαγεῖν παρὰ τὰς ἐν ἡμῖν, ὧν καὶ αἱ ἀρχαὶ ἐν ἡμῖν, καὶ αὐτὰ ἐφ' ἡμῖν καὶ ἑκούσια.
"But if it is manifest that a man is the author of his own actions, and if we are unable to trace our conduct back to any other origins than those within ourselves, then actions of which the origins are within us, themselves depend upon us, and are voluntary."
Epicurus clearly described self-determination as a third thing opposed to chance and necessity. He thought human agents have an autonomous ability to transcend the necessity and chance of some events. This special ability makes us morally responsible for our actions.
The Epicurean "swerve" of the atoms is frequently misinterpreted as claiming that free will depends directly on chance for the cause of actions. The swerve need only break the chain of determinism and allow uncaused alternative possibilities.
Epicurus actually said "..some things happen of necessity (ἀνάγκη), others by chance (τύχη), others through our own agency (παρ' ἡμᾶς). ...necessity destroys responsibility and chance is uncertain; whereas our own actions are autonomous, and it is to them that praise and blame naturally attach.
- R. E. Hobart, "Free Will as Requiring Determination, and Inconceivable Without It," Mind, Vol XLIII, 169 (1934) p.2
- Bob Doyle, "Jamesian Free Will: The Two-stage Model of WIlliam James," William James Studies, April 2010
- Mortimer Adler, The Idea of Freedom: A Dialectical Examination of the Conceptions of Freedom, Doubleday, 1958, p.127
- Adler, The Idea of Freedom, p.135
- Fischer, Free Will: Critical Concepts in Philosophy, Routledge, London 2005, v.I, p.xxiii
- Adler, The Idea of Freedom, p.149
- Adler, The Idea of Freedom, p.149
- The Idea of Freedom: A Dialectical Examination of the Controversies about Freedom, Doubleday (1961), p.225
- Aristotle, Nicomachean Ethics, III, v, 6. Harvard Loeb translation.
- "Chance is Not the Direct Cause of Actions," Information Philosopher
- Epicurus, Letter to Menoeceus, §133