A good starting point for the question of volition can be Gilbert Ryle's description in his The Concept of Mind (p. 63, emphases added):
Volitions have been postulated as special acts, or operations, 'in the
mind', by means of which a mind gets its ideas translated into facts.
I think of some state of affairs which I wish to come into existence
in the physical world, but, as my thinking and wishing are
unexecutive, they require the mediation of a further executive mental
process. So I perform a volition which somehow puts my muscles into
action. Only when a bodily movement has issued from such a volition
can I merit praise or blame for what my hand or tongue has done.
So,
(1) Volition is an internally originating mental process, in contrast to an occurrence by external stimulation.
(2) Volition mediates between decisions and intentions which are regarded as inherently unexecutive and the bodily actions initiated as its result.
Thus, volition requires consciousness as a condition of existence.
It is useful, actually essential, to make a distinction between will and volition, though many writers do not distinguish sharply enough. Will refers to the mental power involving determination and long-term pursuance of a choice, thus demands comprehensive rational/irrational, conscious/unconscious capabilities of the agent, whereas volition is a capacity to effect a short-term, almost immediate, voluntary action (therefore, heartbeat or habits do not accord with the typology of volition). To make the distinction more discernible, we can contrast humans and animals. Animals lack will, while both humans and animals are capable of volition. This contrast is comparable, and indeed related, to the contrast between natural language of humans and animal communication systems.
In social matters, it is universally assumed that individuals are autonomous agents that are capable of and responsible for their deliberate and voluntary) actions. That makes volition be a central concept especially for jurisprudence and ethics. However, philosophically, the question remains:
§621 Let us not forget this: when 'I raise my arm', my arm goes up.
And the problem arises: what is left over if I subtract the fact that
my arm goes up from that fact that I raise my arm?
((Are the kinaesthetic sensations my willing?)) [Ludwig Wittgenstein,
Philosophical Investigations]
A widely held contemporary view is that volition is a weakly grounded theoretical construct, if not a mysterious or illusory concept. As an outstanding proponent of this thread of thought, Ryle says (ibid., p. 67):
So what of volitions themselves? Are they voluntary or involuntary
acts of mind? Clearly either answer leads to absurdities. If I cannot
help willing to pull the trigger, it would be absurd to describe my
pulling it as 'voluntary'. But if my volition to pull the trigger is
voluntary, in the sense assumed by the theory, then it must issue from
a prior volition and that from another ad infinitum. It has been
suggested, to avoid this difficulty, that volitions cannot be
described as either voluntary or involuntary. 'Volition' is a term of
the wrong type to accept either predicate. If so, it would seem to
follow that it is also of the wrong type to accept such predicates as
'virtuous' and 'wicked', 'good' and 'bad', a conclusion which might
embarrass those moralists who use volitions as the sheet-anchor of
their systems.
Ryle likens the status of volition to phlogiston and animal spirits:
'Phlogiston' and 'animal spirits' were technical concepts, though they
have now no utility.
The examples hint at what is at stake on volition. Neither one belongs to philosophy: Phlogiston was proposed as an explanatory concept in chemistry and animal spirits likewise in economics. Indeed, such philosophical criticisms are aligned with the indifferent or sceptical attitude toward volition taken in relevant fields of science.
The scientific attitude is understandable:
- Volition is not behaviourally discernible;
- Volition is not experimentally measurable;
- A brain mechanism as the specific basis of volition is not detected.
But the eliminative view in philosophy is not conclusive at all. A generally accepted requirement of philosophical rigour dictates that philosophy ought to seek compatibility with science, while setting forth broadest possible accounts for the sake of human curiosity. The concept of volition does not violate any established scientific result, thus satisfies compatibility requirement. For the intents and purposes of philosophical theories, it proves to be functional, as to be anticipated upon its legitimate use in social contexts.
The criticism of infinite regress (mentioned by Ryle) is not insurmountable. Simply, the computational view of mind eliminates that criticism, a fortiori so do other theories of mind.
As a supplementary development to remark, there is a growing research interest in the study of volition, specifically, in the field of neuroscience. This is an issue to be examined separately.