A person is responsible for his actions to the extent that he has control or dominion over them. To exercise this dominion two things are requisite: (1) that he be conscious of the nature and effects of his actions; (2) that he perform them of his own free will. These conditions elevate an act above the mechanical and make it human, and as such deserving of reward or punishment.
Man may be impeded and even prevented from exercising dominion over an action in five ways: (1) by a lack of knowledge, through ignorance, inadvertence, or misconception, of the nature and effects of an action; (2) by a prior excitement of his passions; (3) or by a nervousness that momentarily interferes with the exercise of his reason and free will; (4) by physical violence, brought to bear on him contrary to his own will; (5) by fear induced either from within or from without, that paralyzes his reason and will for the time being.
There are also four causes that vitiate the physical integrity of an action but do not deprive man of its dominion. They are: (1) negligence in the mind; (2) indolence in the will; (3) voluntary passion or a bad habit in the disposition; (4) laziness or impetuosity in the performance of an action.