74. A cause is anything which influences the existence of another thing; the latter is called the effect.
A principle or principiant is that from which a being proceeds or originates in any way. It may proceed from it:
1. Logically, as the conclusion does from the premises in reasoning.
2. Physically, by deriving physical being from the principiant. It may do so in two ways: (a) The principiant may produce it, e.g., a tree producing fruit. (b) The principiant may be one of its constituent elements, as a wheel is of a clock.
A principiant is always prior to that which proceeds from it, in one of two ways: (a) In time, by existing sooner. (1) By nature only, when one being produces or constitutes another without existing before it; thus, flame is a principiant of light, roundness of a circle. These two ways of procession and priority do not embrace the peculiar procession by origin only, viz. : when the principiant and what proceeds from it are one identical being. This priority does not exist except in the Blessed Trinity, God the Father being the principiant of God the Son, and these two Persons together the principiant of the Holy Ghost.
75. It will be readily inferred from these definitions:
1. That the terms cause and effect always denote two distinct beings, while the term principiant may denote the same being with that which proceeds from it.
2. That procession does not necessarily denote succession in time.
3. That mere succession in time does not constitute procession; thus, the night succeeds the evening, but does not proceed from it.
4. That therefore the terms principiant and beginning are not synonymous; the principiant has an intrinsic and necessary connection with whatever proceeds from it, while the beginning may have only an extrinsic and accidental connection with what follows it.
76. When a cause is viewed as producing the effect, it is taken formally as a cause; else it is materially a cause. Thus, Columbus was from his boyhood the discoverer of the new world materially, not formally. This distinction between being materially and formally a cause should not be confounded with the other distinction which is next to be explained.
77. There are five kinds of causes: the material cause, the formal; the final; the exemplary, and the efficient.
1. The material cause is the matter out of which a thing is made; thus, steel is the material cause of a watchspring; the distinction between matter and form will be explained further on (No. 127). Speaking analogically, philosophers often apply the name of matter, or material cause, to anything out of which another is produced; thus, they call the faculty of the will the matter, and an act of the will a form.
2. The form, or formal cause, is that which specifies the matter, i.e., which makes the matter be of one species rather than another. The form is: (a) Substantial, if it goes to make the very nature of the substance and cannot be removed without changing that nature; e.g., the vital principle in all plants and animals; for when it ceases to be or departs, the substance or nature of the plant or animal is no more. (b) Accidental, if it can be destroyed without affecting the nature of the substance; e.g., the shape of a hat.
3. The final cause is the end or purpose intended in an action; e.g., when a man exerts himself to acquire riches, the acquisition of riches is a true cause of his exertion. The object itself aimed at, i.e., riches, is the final cause materially considered; the acquisition of riches is the final cause formally considered.
78. Thesis VII. All action is directed to some end or purpose.
Proof. Every action is either done with intelligence or not; if done intelligently, the agent has some motive for his action; he is aiming at some result or other; he acts for an end. If an action is not done with intelligence in the agent, then it proceeds from an impulse of nature; it is then the effect of a physical cause. But physical causes act according to the laws by which the Creator governs the universe -- i.e., by which a wise God directs all things to proper ends. Therefore all action is directed to some end.
79. Objections: 1. A man often acts without a purpose. Answer. He then acts upon an impulse of his nature, and all such action is directed to some end by the Author of nature.
2. If he acted upon a natural impulse his action would be good, since it would come from God but such actions are often evil. Answer. As far as his impulse are physical or purely natural they are not evil; but as far as he freely neglects to control his natural impulses according to the law of reason, they are evil.
3. Many actions are merely accidental. Answer. Every act proceeds from a cause, necessarily or freely, and therefore no action can be accidental; but an action may have effects not intended by the agent, and these may be said to be accidental with regard to him, though they, too, have a definite cause, which acts for a definite end.
80. IV. The exemplary cause is the model conceived by an intelligent agent to the likeness of which he directs the effect of his work. It may be some pattern extrinsic to the agent which he wishes to imitate; thus, an artist sketches a real scene. Or it may be an original image intrinsic to the agent's mind, such as the plan conceived by a painter of the ideal scene which he wishes to represent.
81. V. The efficient cause is the agent that does the action. Every agent acts by its powers or faculties. The power itself called, in the terminology of the Schoolmen, the actus primus, or potential act; the exercise of the power is the actus secundus, or elicited act. The potentiality itself is remote, or proximate, e.g., an infant, from the very fact that it is a human being, has the power of reasoning, but remotely, i e., not in a condition fit for use; a grown person has the same power proximately, i.e., fit for use.
82. The requisites for the exercise of a power are called conditions; these are not properly causes, since they do not bring about an action, but only remove what might prevent action. For instance, citizenship is usually a condition required for voting, but it does not as such induce one to vote. A circumstance which is apt to induce an agent to act, though he might also act without it, is called an occasion; thus, a time of political excitement is an occasion apt to induce many to vote. If occasions influence actions they are real causes.
83. Several further distinctions apply to the efficient cause:
1. If it depends on no other cause, it is called the first cause; such is God alone; all others are second causes.
2. It is properly (per se) the cause of the effect intended and of such other effects as are natural consequences of the action done; thus, the surgeon is properly the cause of the pain he inflicts and of the cure he works. It is accidentally the cause of effects which were neither intended nor naturally to be expected, as when the surgeon causes death.
3. A principal cause is that to which the effect is chiefly attributable; an instrumental cause is that used by a principal cause; as when a lancet is used by a surgeon to open a sore with. The instrumental cause is always made to extend, by him who uses it, to some effect beyond its own competency; e.g., the lancet could not cut skillfully without the skill of the surgeon.
4. A free cause can determine its own actions, a necessary cause cannot do so.
5. A moral cause is one to which an effect is justly imputed, because it induces another agent to act; it does so by command, advice, threats, provocation, etc., as when a naughty boy provokes a man to anger.
84. Since a cause is that which produces an effect, it is evident that it must in some manner contain the effect; for as the axiom expresses it, Nemo dat quod non habet -- "No one gives what he has not." Now, a cause may contain an effect, or rather the perfection which it communicates to the effect, in three ways:
1. Formally, when the cause and effect are of the same species; thus, a plant produces a plant, clouds bring rain, etc.
2. Eminently, when the cause is specifically superior to the effect and contains the perfection of the effect in a higher manner of existence; thus, God contains all the perfection of creatures.
3. Virtually or equivalently, when the cause possesses a superior perfection which can produce the effect; thus, an artist may produce a painting much fairer than himself; he does not possess its beauty eminently, but he possesses an intellect which can conceive and a skillful hand which can express ideal beauty.
When a cause contains an effect formally, it is called a univocal cause; else it is an equivocal cause.
Since an effect is contained in its cause, it is evident that no effect can be more perfect than its cause.
85. We must notice two important limits to causality:
1. A finite cause can only modify an existing subject, but not produce a substance from nothing.
2. No cause can act at a distance, i.e., where it is in no way present; for where it is not, there it is nothing; and nothing can do nothing. Still it suffices that the cause be mediately present to its effect, as when the sun, by the vibrations of ether, gives light and heat to the earth.
Sceptics have denied the reality of causes and effects; but it is evident: (a) That all men distinguish the relation of cause and effect from that of mere succession in time. (b) That all men judge causes and effects to be realities, on which all legislation, all commercial and professional pursuits, as well as all trades, are based. (c) That all languages proclaim this reality, e.g., in the use of such verbs as 'to make,' 'to produce,' 'to push,' 'to pull,' etc., and of such particles as 'why,' 'because,' 'therefore,' etc. (d) That we are conscious of exercising effects, e.g., of raising our hands at will, of speaking, walking, etc.
86. The study of principiants and causes obviously suggests two important principles of certain knowledge, viz.: (a) The principle of the sufficient reason, expressed thus: "There is nothing without a sufficient reason for it." (b) The principle of causality, expressed thus: "Nothing is made or begins to exist but by a cause."
87. Thesis VIII. The principle of the sufficient reason and that of causality are absolutely certain.
Proof 1. The principle of the sufficient reason is an analytical judgment so obviously evident that we cannot rationally deny or even doubt it without thereby implicitly affirming it; for rationally to deny or doubt it we should see some reason for so doing; and thus we admit the validity of the principle, denying it because we see a reason for so doing.
2. The principle of causality flows from the preceding; for when anything begins to exist, there must be a sufficient reason for this beginning. That reason must be either in the object itself that begins to exist or in something else. It cannot be in the object itself; neither in the acts of that object, for it cannot act before it exists; nor in its nature, for then the object would be necessary, but a necessary being is so from eternity and has no beginning. Therefore, the reason of its beginning to exist must be in another being; but this means that it has a cause.
88. Objection: All our knowledge comes through our senses; now, causality does not come to us through our senses; we see facts only as succeeding one another, not as causing one another. Answer. This objection refutes itself; we know what causality means, yet, it says, this knowledge is not conveyed to us by sensation; therefore, it follows we do not get all our knowledge by sense only. It is, however, correct to say that all our knowledge begins in sensation. The relation of cause and effect is not perceived by sense, but by the intellect on occasion of sense-perception (see Nos. 178, etc.); e.g., I understand that my sensations are caused by myself as the eliciting subject, and by the bodies perceived as the determining object of my perceptions.
89. Corollaries. From all these explanations it is evident: 1. That nothing can be its own cause. 2. That two things cannot cause each other. 3. That the principle of causality is not acquired by induction, but is a priori, and only verified by experience. Children show that they have begun to reason when they ask, "Why is this?" (what is the sufficient reason?) "Who made this?" (what is its cause?), etc.