Science has often been dragged into the debate of predestination versus free will. It has been pointed out many times before that, in keeping with the laws of physics, all matter will act in a uniform and predictable manner. This means that, given particular stimuli, one's mind and body will respond in a particular way (controlled by reflexes and decision-making processes). This "fact" leads to the conclusion that everything is predestined, though it should be noted that one's actions will always be in accordance with one's character and virtue.
A cursory glance at this conclusion through the eyes of modern science finds one significant flaw: It treats electron movement as an constant and predictable thing. Quantum mechanics states quite clearly that electron movement is random, and so the position of electrons can only be expressed in terms of probabilities (see Schrodinger's Equation).
That said, one must also bear in mind that the brain works by means of an electrical charge traveling through neural circuits in the brain. When taken to its reasonable ends, this means that given the exact same stimulus in the exact same context, a person may not react in the same manner. Also, what stimulus they are subjected to may change due to the unpredictable actions of electrons which, due to the Butterfly Effect, will impose significant change on the sum total of everything that happens.
The principle of applying modern science to the philosophical debate of free will vs. predestination results in a relatively innovative concept which I call Quantum Free Will. This means that one's actions and decisions will not always be the same, though the individual's control over their own actions is no more than if it were solely predestined. From this, one may reach the conclusion that virtue is an inherent characteristic that defines one's possible courses of action, but this inherent virtue is as subject to change as one's moral judgements.