The problem is to reconcile our everyday consciousness of ourselves as agents, with the best view of what science tells us that we are. Determinism is one part of the problem. It may be defined as the doctrine that every event has a cause. More precisely, for any event e, there will be some antecedent state of nature, N, and a law of nature, L, such that given L, N will be followed by e. But if this is true of every event, it is true of events such as my doing something or choosing to do something. So my choosing or doing something is fixed by some antecedent state N and the laws. Since determinism is universal these in turn are fixed, and so backwards to events for which I am clearly not responsible (events before my birth, for example). So no events can be voluntary or free, where that means that they come about purely because of my willing them when I could have done otherwise. If determinism is true, then there will be antecedent states and laws already determining such events; how then can I truly be said to be their author, or be responsible for them? Reactions to this problem are commonly classified as:

1. (i) hard determinism. This accepts the conflict and denies that you have real freedom or responsibility.

2. (ii) Soft determinism or compatibilism. Reactions in this family assert that everything you should want from a notion of freedom is quite compatible with determinism. In particular, even if your action is caused, it can often be true of you that you could have done otherwise if you had chosen, and this may be enough to render you liable to be held responsible or to be blamed if what you did was unacceptable (the fact that previous events will have caused you to choose as you did is deemed irrelevant on this option).

3. (iii) Libertarianism. This is the view that, while compatibilism is only an evasion, there is a more substantive, real notion of freedom that can yet be preserved in the face of determinism (or of indeterminism). In Kant, while the empirical or phenomenal self is determined and not free, the noumenal or rational self is capable of rational, free action.

But since the noumenal self exists outside the categories of space and time, this freedom seems to be of doubtful value. Other libertarian avenues include suggesting that the problem is badly framed, for instance because the definition of determinism breaks down; or postulating a special category of uncaused acts of volition; or suggesting that there are two independent but consistent ways of looking at an agent, the scientific and the humanistic, and it is only through confusing them that the problem seems urgent. None of these avenues has gained general popularity. It is an error to confuse determinism and fatalism. See also dilemma of determinism.