In my Portuguese-language edition of Régis Jolivet’s Cours de philosophie, near the end of §138, I find (the equivalent of) this sentence.
Without a doubt, intelligence has organic conditions, which are the nerves and the brain, but conditions are not causes. (To play the violin, the artist requires a bow. But the bow is not the cause of the melody: it is only the condition.) Therefore, we must say with Aristotle, that “we think without an organ of thought” (88).
The number 88 refers to §88, which says much the same thing. (Update 2021-05-02: it would have been more useful to refer to §196; see the addendum.) This sentence and example perplexed me, though; what is he on about? What is it about the violin that makes it a condition and not a cause? Is it not a material cause, in the Aristotelian reckoning? What are conditions and causes, anyway? What is the difference? Does anyone ever explain that?
The answer to the last question is that almost no one ever explains that, for some reason. We use the words recklessly and do not care.
I surveyed some people in a philosophy forum about this, on whether (a) all conditions are causes, and whether (b) all causes are conditions. The result was dishearteningly close; some people thought (1) that both propositions are true, which would ruin Jolivet’s doctrine, by making the terms coextensive. Some people thought (2) that neither is true, which no one really explained. Some people thought (3) that conditions ⊃ causes. Thankfully, apparently no one thought (4) that causes ⊃ conditions.
If a close number of people agree with each of these possibilities, then possibility (3) is made the most plausible, since the supporters of possibility (1) agree with it about (a), and the supporters of possibility (2) agree with it about (b). Sure enough, (3) seems to be the opinion defended by Mackie, who defined causes as a particular type of conditions.
Mackie’s opinion is likely to be quite interesting, but I have no reason to think that his analysis agrees with the use of these terms in scholastic manuals such as the one I was reading. When I asked a different forum for resources on the distinction, I was linked to a paper, based on Suárez’s metaphysics, that explicitly mentioned Mackie’s analysis as unsatisfactory, for its “inability to draw a sharp metaphysical distinction between ‘real’ causes and mere background conditions.”
Whatever that paper concludes, it is much more likely to agree with the book I was reading. It is also hosted on the highly useful Jacques Maritain Center website, which gave me the idea to search that website for more information. Doing so, I found two (2) books that said something useful. So, as the result of my research, I will now end this post by quoting serially from that paper, from the two books I found in the same website, and finally twice from an interesting book I found on Google Books, which, attempting to argue a similar point, that sensation is a mere condition of reasoning, quotes several illustrations of the distinction from different authors.
[I]t is the active communication of esse to an entity that constitutes the core of efficient causality, and Suárez’s account presupposes that the production or conservation of any effect in nature involves some agent’s communicating esse of some sort to some recipient. This is true even when a patient suffers a loss or privation of esse as the result of an agent’s causal influence--as, for instance, when a living organism dies or when someone is blinded by being struck in the eye. What occurs in such cases is the introduction into the patient of a formal determination which is incompatible with the form that the patient is thus deprived of. Such examples should make us aware that even though every instance of efficient causality involves a giving of esse or perfection, this does not mean that the patient is itself more perfect absolutely speaking as a result of the agent’s influence.
Given this background, we are now in a position to appreciate Suárez’s characterization of a per se and immediate efficient cause:
A per se cause is a cause on which the effect directly depends with respect to that proper esse which it has insofar as it is an effect. And since this cause alone is a cause in the proper and absolute sense, almost the whole next disputation [Disputation 18] will be concerned with it alone. [—DM 18, sect. II, §2.]
More formally,
x is a per se and immediate efficient cause of y at t if and only if x, by acting, directly communicates esse to y at t.
This, according to Suárez, is the metaphysical core of efficient causality. All the other related notions that philosophers, past and present, have used to characterize causality—e.g., constant conjunction, causal regularity, statistical correlation, causal law, the transmission of probabilities, INUS condition—must, if they have any relevance to causality at all, find their place within the framework established by this basic causal notion.
Suárez goes on to distinguish two main types of per se causes, viz., principal and instrumental, where an instrumental cause is, in general, an agent that is employed in some way by a principal cause in effecting its own proper effect.[...]
— Alfred J. Freddoso, A Suarezian Model of Efficient Causality, §4.2¶8ff.
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.
— Charles Coppens, S.J., Mental Philosophy, §82
“A cause is more than a condition.” This saying is of a different type from those previously explained, and leads some people to a hazy and erroneous idea, that a condition may positively do something, without being a cause. We must try to distinguish different senses.
The most pure instance of a condition is one which does nothing, but consists in the mere absence of an obstacle. Thus a window is a condition of seeing, because it does not impede the course of light; it may be a simple hole, as in more primitive buildings, or it may be glass, inasmuch as it has the negative quality of not appreciably obstructing the luminiferous waves. But the best glass gives no light of its own, as we may verify for ourselves at night, when the candles are out.
The second case of a “condition,” is one where the reality does something positive, but, as a cause, it is so comparatively inferior in rank, or so far removed from the final result as not to be reckoned among the causes. This is instanced by the oft-quoted relation of the bellows-blower to the organist. The former has positively to cause something, but his work is unskilled labour, and he is not the immediate producer of the musical sound. If we were so inclined we might also call the organist a condition; for he only opens the vents and lets the imprisoned air act on the tubes; but because it requires much skill to press the keys in the ways required, the actions are dignified with the title of principal causes. The remoteness of the organ-builders, or of the musical composer from the actual playing at the time, would lower them to “conditions,” though in point of dignity they might claim to be causes.
A third meaning of “condition” refers to a moral agent, who is not simply made to act upon the fulfilment of certain “conditions,” but chooses to act where these motives are presented. Thus, the grace of God is sometimes “conditioned” by certain acts on the part of man, though there is no obligation, not even one consequent on a promise given. If not the free acts only, at least the free acts especially, of a moral agent deserve to be styled acts dependent on conditions.
We conclude that in reference to a moral agent, so far as his action is distinctively moral, a condition furnishes a requirement without which he will not act: while in reference to physical agency as such, a condition is either a remote or a comparatively insignificant cause, or else it is the absence of a possible obstacle.
An occasion is a conjunction of causes, efficient and material. Those who speak of the evolution of our solar systems from a primitive nebula, have noticed that, not only the primitive elements of matter in such a nebula need to be accounted for, but that likewise their collocation, their arrangement, their distribution, is a distinct fact about them, of which some account should be rendered. Now an occasion answers to this collocation: it always must have a distinct cause, but in itself we regard it as an incident of causation, not as a cause. If on the occasion when a flower is ready to scatter its seeds a high wind arises, they are dispersed all the further; if on the occasion when a tile falls from a roof a man is passing just under the spot where it falls, he is injured. Our ordinary practice is, to take the conjunction of two or more causes which we regard as practically independent, to ignore the cause or causes which have brought them into conjunction, and then, to speak of their combination as occasional. In the example of a free agent, he may choose his occasions because of their special fitness to his purpose, and they may become conditions of his action.
— John Rickaby, S.J., General Metaphysics, 2.3.4e
It is admitted that apart from sensation and sense-perception there can be no true cognition. Still it is not sensible experience alone which produces consciousness. Sensible experience is the occasion (the condition), but the reason is the true cause of that knowledge we call consciousness.
First notions are not transformed but informed sensations—that is sensations illuminated and informed by rational ideas, for without ideas, sensation has no form. The ideas of the Supreme Reason are symbolized or embodied in nature, and it is the apperception of these ideas by the reason of man (made in the image of God) which enables him to translate the affections of the sensibility into consciousness and thought. All light, all comprehension, all coördination comes from the reason. Therefore, reason is the true cause of knowledge.
Note.—Between the real cause and the occasion of any phenomenon there is a clear distinction. The former implies a real, efficient, productive power; the latter, some condition or conditions under which the power is manifested. I cast a grain of wheat into the earth. The occasion of its germination and development into leaf, stem, ear, and grain, is light, warmth, moisture, etc.; but these are by no means the cause. The cause is the mysterious, organizing force which is immanent in the seed. The rest are but conditions under which or upon which the cause produces the effect.
— Benjamin Franklin Cocker, Handbook of Philosophy, Division I, p. 64 (PDF p. 133)
Reason is the real Cause, Sensation and sensible Experience are the Conditions of real Knowledge. It is admitted that apart from sensation and experience there can be no knowledge of the external world; but it is not sensation, nor a repetition of various sensations which constitutes knowledge. Sensation is merely the occasion; the true cause of knowledge is the intuitive reason with its universal and necessary ideas. Thus, without the observation of contiguous and successive change there could be no clear idea of cause; but whenever change is perceived, it presents itself at once to the reason as a manifestation of power, and refers us to a causal ground. Without the perception, by sense, of the collocation and disposition of objects or parts of objects, there could be no clear idea of design; but on such collocations and arrangements being presented, the mind intuitively regards them as being intended, or designed. The sensation or perception is not the cause of the judgment, it is simply the occasion. The idea of power is not seen by the senses, it is given by the reason. The purpose, or design, is not perceived by the material eye, it is not in the mechanism at all. The design, or purpose, exists in the mind of the maker of the machine and is perceived by the eye of reason in the arrangement of the parts of the machine, that is, the same idea is excited or occasioned in our mind which existed in the mind of the maker or the contriver of the mechanism.
“We always single out one dynamical antecedent—the power which does the work, or one rational antecedent—the purpose for which work is done, from the aggregate of material conditions under which these are manifested.” — Dr. Carpenter: “Nature,” vol. vi., p. 210.
“There is danger of confounding conditions and causes. The dilute acid in the battery will attack the zinc only on condition that you connect the zinc and platinum externally by means of a conductor; but this does not make the conductor the agent which dissolves the zinc. I build a wall behind my grape trellis and I find the ripening of the fruit accelerated ; but it is not the wall which does the work, it is still, as before, the sun. The amount of light emitted by my lamp is determined, within certain limits, by the height of the wick; but this does not render the wick the cause of the light. The varying wick is only a varying condition of a varying result of a varying activity of a constant physical force—chemical action between oil and oxygen. Similarly, the amount of thought which I can evolve is conditioned by all the affections and conditions of the brain. My poetry and my philosophy are indeed correlated to brain and blood and oxygen and beef-steak, but only in the same way as my boots are correlated to calf-skin and tan-bark and black-wax. These conditioned the exercise of the boot-maker’s skill; beefsteak conditioned the exercise of mine. It is quite true that the activity in both cases has other conditions, but it is also true that none of these conditions can be elevated to the dignity of causes. The physical scientist is sometimes hoodwinked by the exact gradation of mental activity to the condition of the brain, and commits the mistake of clothing condition with the character of cause.” — Dr. Winchell: “Thoughts on Causality,” pp. 21, 22.
“Conditions are not actively productive, but are passively permissive; they do not cause variation in any direction, but they permit and favor a tendency which already exists.” — Huxley: “Critiques,” etc., p. 273.
“To make the stimulating condition or occasion the cause of, cognition is as illogical as to make the setting of the pointer-dog, which aroused the attention of the sportsman, the cause of the killing of the game.” — McCosh: “Defence,” etc., p. 86.
— Benjamin Franklin Cocker, Handbook of Philosophy, Division I, pp. 87–88 (PDF pp. 180–181)
Update 2021-05-02: The same Cours de philosophie turns out to answer this question in a later paragraph. It did not occur to me to skip ahead, and I took a long time to get to this paragraph because I had only read this book intermittently. It is probably no harm that I did some research, and this blog post, before reading ahead; what I had read does not conflict with the book’s own answer. In §196, it says the equivalent of this:
Cause, condition, occasion.— It is necessary to distinguish carefully these three notions. The condition is that which allows the cause to produce its effect, be it positively, as an instrument or a means (so the bow is, to the violinist, the condition of the melody which he will play), – be it negatively, by removing obstacles (so, the pianist must have his piano tuned, if he is to play aright).
The occasion is an accidental circumstance, which creates conditions favorable to the action (so, good weather is the occasion for me to decide to take a walk). Not even the most favorable condition, not even the most indispensable condition (called a condition sine qua non) can be confused with the cause properly so called, for the effect does not depend on it essentially, but accidentally.
