Kant's compatibilism

There are a number of well-known incompatibilist objections to the spontaneity argument. The first and most obvious is that “liberty of spontaneity” is a wholly inadequate conception of moral freedom. Lying at the heart of Hume's compatibilism are three conclusions that constitute the core of his compatibilst position on this subject as generally understood:

• Actions that are subject to moral evaluation are not distinguished from those that are not by an absence of cause but rather by a different type of cause. Responsible or morally free actions are caused by our own willings, whereas unfree actions are brought about by causes external to the agent. Let us call the argument that seeks to establish this conclusion the “spontaneity argument”
• A liberty which means “a negation of necessity and causes” (T, 2.3.2.1/407) has no existence and would make morality impossible. Let us call the argument which seeks to establish this conclusion the “antilibertarian argument”.
• Necessity, properly understood, is the constant conjunction of objects and the inference of the mind from one object to the other (T, 2.3.1.4/400; EU, 8.5/82). Let us call the argument which seeks to establish this conclusion the “necessity argument”.

Kant, famously, describes this account of moral freedom as a “wretched subterfuge” and suggests that a freedom of this kind, the spontaneity argument from an "internal cause", belongs only to a clock that moves its hands by means of internal causes.

If our will is itself determined by antecedent natural causes, then we are no more accountable for our actions than any other mechanical object whose movements are internally conditioned. Individuals who enjoy nothing more than a liberty of this nature are, the incompatibilist claims, little more than “robots” or “puppets” subject to the play of fate. This general line of criticism against the spontaneity argument leads directly to two further important criticisms.

The incompatibilist maintains that if our choices are themselves determined by antecedent causes then we could never choose otherwise than we do. Given the antecedent causal conditions, we must always act as we do. We cannot, therefore, be held responsible for our conduct since, on this account, we have no “genuine alternatives” or “open possibilities” available to us. Moreover, incompatibilists do not accept that Hume's notion of “hypothetical liberty”, as presented in the Enquiry, can deal with this objection.

It is true, of course, that hypothetical liberty leaves room for the truth of conditionals that suggest that we could have acted otherwise if we had chosen to do so. However, it still remains the case, the incompatibilist argues, that the agent could not have chosen otherwise given the actual circumstances. Responsibility, they claim, requires categorical freedom to choose otherwise in the same circumstances. Hypothetical freedom alone will not suffice. One way of expressing this point in more general terms is that the incompatibililst holds that for responsibility we need more than freedom of action, we also need freedom of will — understood as a power to choose between open alternatives. Failing this, the agent has no ultimate control over his conduct.

Kant shares Hume's view that causal necessity governs human actions and other events, insofar as they are all considered part of the natural world, and that humans are nonetheless free. But Kant rejects Hume's view that moral and natural actions must be viewed as part of a single chain of causes, effects, and explanations. 

Indeed, if they were, and if we accepted natural causal laws as universal and deterministic, there could be no freedom of the sort Kant is ultimately after for his moral philosophy (i.e., autonomy).

Kant renders freedom and determinism consistent by distinguishing between two worlds of which we are members.

As members of the phenomenal world, our actions can be understood in purely deterministic terms, according to natural causal laws; but as members of the noumenal world, we are free. (Lest the notion of “two worlds” seem spooky or wildly implausible, Kant states:

“The concept of a world of understanding is … only a standpoint that reason sees itself constrained to take outside appearances in order to think of itself as practical” (G 4:458).)

Thus, Kant endorses “not only the compatibility of freedom and determinism, but also the compatibility of compatibilism and incompatibilism” (Wood 1984, 74).

He has been treating freedom “only as a transcendental idea” by which reason is led to think of its ability to begin a series of events in the sensible world.

“What we have alone been able to show and what we have alone been concerned to show, is that causality through freedom is at least not incompatible with nature” (A 557–8/B585–6).

On the metaphysical nature of Kant’s view

“For science this is a strange metaphysical notion, a conception of causation nowhere else applied in nature. But that's precisely the "antinomy" Kant thinks is resolvable. We cannot totally rule out a causal determinism in the phenomenal world (our heredity, environment, emotions, feelings belong to the phenomenal world) but Kant argues for "agent-causation", a cause emanating from reason itself. Reason determines the will to act against antecedent causes that bubble up in our physiological nature. Practical reason instructs the will (where freedom reigns) to act in a moral situation according to a noumenal choice to do our duty".

Professor http://www.americangoethesociety.org/docs/kant_2007_05_10.pdf