Pirates & Revolutionaries: Hume, A Treatise of Human Nature, Book 1, Part 3, Sect 13 Of Unphilosophical Probability, §§313-332

by Corry Shores
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[The following is summary, up to the end where I reproduce this section in full. My commentary is in brackets. Paragraph headings are my own.]

David Hume

A Treatise of Human Nature

Book I: Of the Understanding

Part III: Of Knowledge and Probability

Section XIII: Of Unphilosophical Probability

§313 Time's Refutations

We previously discussed types of probabilistic reasoning. It is intuitive inductive reasoning. But philosophy considers it a valid foundation for belief and opinion.

Yet, there are other types of reasoning that are grounded in the same mental processes. But they are not accepted in philosophy.

Hume will now explain the first type of invalid probabilistic reasoning.

We previously noted that there were two ways to diminish the force of our probabilistic inferences. Either

a) we obtain contrary evidence,

b) we may encounter a situation that only loosely resembles past experiences, or

c) for other reasons (which we will discuss), the inferred image loses its "color."

Now consider that every morning we see that the sun rises. So our inference is strong. But not every night the moon rises. It's pattern is far more difficult to discern. Hence when night falls, we are not so quick to infer that the moon will appear. For, it might have been a while since we last saw the moon in the sky.

The idea of the morning sun rising is remarkably vibrant in our minds. But the idea of the moon in the sky is less vivid, because periods of time with no impressions causes its vibrancy to "fade" a little.

No consider a scientific experiment that demonstrates the rate of acceleration for a falling object. Perhaps years have passed since anyone repeated that experiment. So the image of it fades from our minds. But in philosophy this is not proper grounds to refute the experiment's findings. Yet, imagine 20 years pass and we have not seen this demonstration. We then wonder to ourselves about the acceleration of falling bodies. The day after the experiment we were quick to recall. But now it takes slightly longer to call it to mind. And we might even want to repeat the experiment again to be sure, before passing that information on to someone else.

So Hume wants us to see that there is a way that certain inferences became "refuted" by the passing of time between repetitions. But these refutations are not admitted as valid reasoning in philosophy.

The argument, which we found on any matter of fact we remember, is more or less convincing according as the fact is recent or remote; and though the difference in these degrees of evidence be not received by philosophy as solid and legitimate; because in that case an argument must have a different force to day, from what it shall have a month hence; yet notwithstanding the opposition of philosophy, it is certain, this circumstance has a considerable influence on the understanding, and secretly changes the authority of the same argument, according to the different times, in which it is proposed to us. A greater force and vivacity in the impression naturally conveys a greater to the related idea; and it is on the degrees of force and vivacity, that the belief depends, according to the foregoing system. (143c)

§314 The Force of Drink: The Power of Recent Impressions

The next type of philosophically inadmissible inference is practically like the first one. To understand it, Hume has us imagine a drunkard. He sees his friend die of drunken debauchery. So fresh the memory holds him, that he quits drink. But after a few weeks, the memory loses force. His drinking prevails.

a drunkard, who has seen his companion die of a debauch, is struck with that instance for some time, and dreads a like accident for himself: But as the memory of it decays away by degrees, his former security returns, and the danger seems less certain and real. (144b boldface mine)

We saw that experiences that have not been confirmed in a while lose their force of vivacity. Likewise, experiences that have just occurred are more vibrant, and hence more compelling.

An experiment, that is recent and fresh in the memory, affects us more than one that is in some measure obliterated; and has a superior influence on the judgment, as well as on the passions. A lively impression produces more assurance than a faint one; because it has more original force to communicate to the related idea, which thereby acquires a greater force and vivacity. A recent observation has a like effect; because the custom and transition is there more entire, and preserves better the original force in the communication. (143-144)

§315 Long Arguments Lack Imagination

We have seen how we make inferences based on past experiences. These are probabilistic reasonings. We also know that we may make argumentation based solely on logical proofs. A simple argument might be "All men are mortal. Socrates is a man. Hence Socrates is mortal."

But suppose someone makes this argument: "All men are mortal. Socrates is a man. All men are animals. All animals try to survive. All who try to survive exhibit Spinoza's conatus. All instances of Spinoza's conatus illustrate this idea. Hence Socrates illustrates Spinoza's notion of conatus." By the time we arrive at the conclusion, we begin to lose the thread of reasoning. And the conclusion seems odd. We could have added even more intermediate inferences to make the series longer.

Or imagine you and a friend are walking down a dark street at night. Muggers attack. They brutally kill your friend in front of you. Later you are asked to testify in court. Your very observance of this act is proof for the prosecution's argument against the criminals. Or imagine instead that it was not you but your brother who saw your friend's brutal murder. Your brother tells you about it. You are in disbelief, but you know your brother would not lie about this. Or perhaps it was someone you never met who witnesses your friend's death. You discover it the next day in the newspapers. You are in even more disbelief. You make some phone calls to be sure, and yes, it's true, you lost your friend. Or perhaps someday long after the event, you tell your daughter about it. She does not believe you at first. So she researches old newspaper articles and finds that it is true. Previously Hume had us consider Caesar's murder at the senate [see §194]. We did not witness the murder, nor did anyone we know see it. In fact, its been many hundreds of years since it happened. But the event was passed down through the generations. This is another type of extended inferential chain. It regresses back to a first-hand impression of the event. So we are far less apt to believe it. In fact, there are many who doubt well documented historical events such as the Holocaust.

'Tis from the original impression, that the vivacity of all the ideas is deriv'd, by means of the customary transition of the imagination; and 'Tis evident this vivacity must gradually decay in proportion to the distance, and must lose somewhat in each transition. Sometimes this distance has a greater influence than even contrary experiments wou'd have; and a man may receive a more lively conviction from a probable reasoning, which is close and immediate, than from a long chain of consequences, tho' just and conclusive in each part. Nay 'tis seldom such reasonings produce any conviction; and one must have a very strong and firm imagination to preserve the evidence to the end, where it passes thro' so many stages. (144c.d boldface mine)

§316 Do Historians Believe Ideas They Can't Conceive?

Hume now addresses a possible objection based on these long chains of inference. The original sense-impression's vivacity diminishes with each transmission. So we might expect that no one could believe in Caesar's murder anymore.

Perhaps, therefore, it may be concluded from the precedent reasoning, that the evidence of all ancient history must now be lost; or at least, will be lost in time, as the chain of causes encreases, and runs on to a greater length. (145b)

But there is an even more challenging critique. Hume's claim is that our belief's strength depends on our idea's vivacity. And he also argues that ideas lose their vivacity as more inferences separate us from the original sense-impression. Now, we can easily see that many people believe in Caesar's murder. But we might also conclude that there is no vivacity to that idea, given their separation from the cause. So then they would have belief without vivacity. This contradicts Hume's central thesis that belief depends on vivacity.

§317 Is Religion Probably Lost?

Those who witnessed Christ's Crucifixion can be certain it happened. Those who heard about it the next day may think there is a very high probability it is true. Their children's generations may also think it is very probable. But each time the event is transmitted, the vivacity of the idea weakens. Hence we come to believe it less. And thus with each transmission, the idea becomes less certain and probable.

§318 History in Hi-Fi

Hume replies. After the first transmission from witness to documenter, there was a loss of vivacity. But then, as the idea for the event is transmitted from historian to historian, it is done so through copying and reprinting books. So long as the fidelity to the original documents is maintained, there is no loss to the vivacity of the idea from its first documentation.

tho' the links are innumerable, that connect any original fact with the present impression, which is the foundation of belief; yet they are all of the same kind, and depend on the fidelity of Printers and Copyists. One edition passes into another, and that into a third, and so on, till we come to that volume we peruse at present. There is no variation in the steps. After we know one we know all of them; and after we have made one, we can have no scruple as to the rest. This circumstance alone preserves the evidence of history, and will perpetuate the memory of the present age to the latest posterity. (146a.b boldface mine)

In this way, such long chains of argumentation really have the size of only one or two major transmissions, with all the rest being repetitions of a the same transmission with no loss of fidelity to the original idea.

§319

Enjoying Conversation with the Irish and French

despite

Obstruction from Prejudice

To understand the next species of unphilosophical reasoning, Hume first has us consider these ideas:

a) a conversation with an Irishman is often very enjoyable, and

b) a Frenchman is usually judicious in his thought and discourse.

However, we might have rashly formed general rules that are prejudicial. For example, despite the above facts, we might have erroneously come to believe that

1) an Irishman cannot have wit, and

2) a Frenchman cannot have solidity.

Our human nature makes us vulnerable to such errors. And prejudicial reasoning is rightly not admissible in philosophical reasoning.

§320 The Indiscriminant Inferences of Drunks and Gluttons

We might wonder why it is that we construct just erroneous prejudicial rules when experience teaches us otherwise.

First recall that we form causal judgments based on certain past experiences.

[We give our nephew a cookie, and he smiles. Countless times we have given him a cookie, and he responds this way. In these instances, we noticed two objects were consistently found to be together: cookie-gift and nephew-smile. Then one day we learn he is sick. But we have traveled to another city. So we call a flower delivery-service to have a cookie-bouquet sent to his door. We do not see our nephew's face when he receives the cookies. Nonetheless, we can see his smile in our mind. Hence] our imaginations form the habit of moving from cause to effect, even if the effect is not sensibly present.

But there is another complication that Hume illustrates with the following examples of analogical transference:

A man, who has contracted a custom of eating fruit by the use of pears or peaches, will satisfy himself with melons, where he cannot find his favourite fruit; as one, who has become a drunkard by the use of red wines, will be carried almost with the same violence to white, if presented to him. (147c)

Melons are not pears or peaches. But they fulfill the same desire. So in the sense that they both are fruit-satisfactions, they are analogous objects. So normally the man has a pear or peach desire. He sees the pear or peach. He eats it, and feels satisfaction. In the future he might see a peach in a grocery aisle. His imagination will infer the idea of appetite-satisfaction. For that reason, he buys the peach. But one day he goes to the grocer and there are no peaches. No problem. But he then discovers there are no pears either. Yet, he sees melons in the nearby basket. The melons are loosely like peaches or pears. So his imagination still infers the idea of appetite satisfaction. However, it is not as vivid an idea. [see §312 for more on the effects of analogous causes.]

[Likewise for the drunkard. Like a fanatical pagan, he lives for Hungarian Bulls Blood red wine. And for good reason, it gives him a berserker's mania. The winery's home town fended off an Ottoman invasion in the 16th century by means of this blood-thick wine:

During the siege, the citizens of Eger opened their wine cellars and drank red wine to give them strength to fight off the Turks. The wine spilled over their beards and onto their armor, coloring them blood red. As the citizens continued their valiant fight against the invading Turks, word spread quickly that the Hungarians were drinking the blood of bulls to make themselves strong and fierce. The superstitious Turks were fearful and demoralized. As a result, the siege was broken. from www.bullsblood.com)

Such imagery became tightly associated with his many memories of drunken revelry on this wine. But one day the wine shop was out of his choice drink. Only white wines remained. Nevertheless, he drank the alternatives. While the images of drunken berserker battle-cries and midnight revelry were much fainter and less forcefull in his mind, he still assures us he had a fantastic night nonetheless.]

So we see that we may transfer the force of probabilistic inferences to analogous causes. However, the less the resemblance, the lower the inferential force.

§321 Confusing Complications

So our customs or habits are the foundations for our judgments. But we find that sometimes we carry prejudicial judgments do not reflect our true sentiments. We wonder, do they come from a different source or form the same as our more authentic judgments?

[Let's first consider the complexities involved in our judgment's formation. Let's say that we are a baseball player. We had a full meal before eating, and we felt ready to play. It is our first time at bat ever in a major game. Before nearing the plate, we notice that our shoes are clod with dirt. Fearing that this could cause us to slip, we tap our left foot three times with our bat to clean that shoe. But we only need to tap the right shoe once to clean it. We then hit the ball on the first pitch, and earn our team's appreciation. The next time we play, we have a full meal, and we repeat the foot tapping ritual: three to the left, one to the right. We again hit the ball. Some days this ritual does not work. But it is not until after many games that we later conclude that the real cause was the fact that we did not eat a full meal that day.]

So when we notice effects, there are often many other things conjoined with it. Any of these could be the cause. But what determines the cause sometimes requires many repeated experiences to extract all the inconsequential accompaniments to the real cause.

Now we may observe, that when these superfluous circumstances are numerous, and remarkable, and frequently conjoined with the essential, they have such an influence on the imagination, that even in the absence of the latter they carry us on to the conception of the usual effect, and give to that conception a force and vivacity, which make it superior to the mere fictions of the fancy. We may correct this propensity by a reflection on the nature of those circumstances: but it is still certain, that custom takes the start, and gives a biass to the imagination. (148b boldface mine)

So we see we sometimes draw incorrect inferences from these complex cases. But we note that the same mental process that produces correct inferences is also what produces inaccurate ones as well, and it is by habit that both can be reinforced.

§322 Caged by Irrational Fears

Hume will now dramatically illustrate this phenomenon. He has us imagine a man hanging from a high tower in an iron cage. [image credits provided at the entry's end.]

The man can feel the strength of the iron. So he knows he will not fall. But he also sees the incredible depth below him. He has felt the danger of such a view many times before when standing at the edge of cliffs. So he cannot now help but tremble from fear.

consider the case of a man, who, being hung out from a high tower in a cage of iron cannot forbear trembling, when he surveys the precipice below him, though he knows himself to be perfectly secure from falling, by his experience of the solidity of the iron, which supports him; and though the ideas of fall and descent, and harm and death, be derived solely from custom and experience. (148c)

So we see that hanging from a great distance in an iron cage is analogous to standing at a cliff's edge. Many times in the past the man has come close to injuring himself from being on heights. So whenever on high, he infers danger. Hence even though he is perfectly safe, he still reacts as though he were in danger of the drop below him.

The same custom goes beyond the instances, from which it is deriv'd, and to which it perfectly corresponds; and influences his ideas of such objects as are in some respect resembling, but fall not precisely under the same rule. The circumstances of depth and descent strike so strongly upon him, that their influence cannot be destroy'd by the contrary circumstances of support and solidity, which ought to give him a perfect security. His imagination runs away with its object, and excites a passion proportion'd to it. That passion returns back upon the imagination and inlivens the idea; which lively idea has a new influence on the passion, and in its turn augments its force and violence; and both his fancy and affections, thus mutually supporting each other, cause the whole to have a very great influence upon him. (148c-149 emphasis mine)

§323 Our Imaginations Make Our Judgments

According to Hume's system, all reasoning results from customs that vivify imagined ideas. Hence our judgment and imagination can never be contrary.

We form general rules such as, eating a full meal helps us function. We obtain them by experimentally eliminating possible causes so to deduce the proper one.

these rules are formed on the nature of our understanding, and on our experience of its operations in the judgments we form concerning objects. By them we learn to distinguish the accidental circumstances from the efficacious causes; and when we find that an effect can be produced without the concurrence of any particular circumstance, we conclude that that circumstance makes not a part of the efficacious cause, however frequently conjoined with it. (149bc)

However, consider again the baseball player example. Every time he performed well, he had a full meal. But many of the times he had a good game, he also tapped his left foot three times, and his right once. Soon he realizes this has nothing to do with it. Then, he thinks that he knows the real cause by means of his judgments. But he also feels the tendency to continue tapping his feet. For the image of its causal relation to doing well is so vibrant from frequent recurrence. But he does not think that he judges his foot-tapping to be helpful. Rather, he thinks he is 'imagining things,' or that he imagines the ritual to make a difference, even though he judges it to have no influence. Hume says this is mistake: there is not a difference between our judgment and imagination in these matters. He really just judges the full meal to be the more probable cause, because he imagines that idea with more vibrancy. Hence he believes it more. After learning that the foot-tapping has nothing to do with his performance, he stops treating it as a cause, and slowly the vibrancy of the real cause overpowers it to the point where he no longer feels the compulsion to tap his feet.

as this frequent conjunction necessarily makes it have some effect on the imagination, in spite of the opposite conclusion from general rules, the opposition of these two principles produces a contrariety in our thoughts, and causes us to ascribe the one inference to our judgment, and the other to our imagination. The general rule is attributed to our judgment; as being more extensive and constant. The exception to the imagination, as being more capricious and uncertain. (149c.d)

§324 Do Two Wrong Inferences Make a Philosophical Right?

So let's consider again the caged man hanging. He had past experiences with dangerous cliffs. Thereby, he formed the general rule that heights are dangerous. He has also experienced iron gates protecting him from intruders. He knows that great amounts of force are not going to break such wrought-iron girders and sturdy chains. So he has also formed another rule that heavy iron structures will support his weight. Hence the two rules clash: one rule says he is in danger, another one says he is safe. But the imagery of danger is more vibrant in his imagination. Thus his fear over-powers him.

So when hanging from the tower, the situation resembles when standing on the cliff's edge.

When an object appears, that resembles any cause in very considerable circumstances, the imagination naturally carries us to a lively conception of the usual effect, tho' the object be different in the most material and most efficacious circumstances from that cause. (149-150)

Perhaps previously this man saw someone else in the cage, and thought, "why is he so afraid?" Because when we rationally reason about the matter, we will conclude that the caged person is safe. And maybe some caged people do reason this way, and overcome their fear.

But what takes-over first is the general rule that one is in danger. Then, after thinking rationally, the second general rule prevails, that he is in fact held secure by the sturdy iron. Depending on the person's disposition, either the first or the second general rule will govern his inferences.

This is a second influence of general rules, and implies the condemnation of the former. Sometimes the one, sometimes the other prevails, according to the disposition and character of the person. The vulgar are commonly guided by the first, and wise men by the second. (150b)

But now Hume's theory has enabled another objection. We know that reasoning from general rules is inadmissible, because often it is based on prejudice or it does not attend to the important details that distinguish analogous situations. So we often make inaccurate inferences from these general rules. But now it seems that the only way to rectify one generalized inference is by means of yet another one. Hence we might object that all reasoning is inevitably unphilosophical.

§325 General Rules Make Us a Fool and Coxcomb.

Without Them, Insults Sting Stealthily

So before the caged man was suspended, first he was placed in the cage at the top of the tower. There he could tell that the cage and the chain would surely support him. So he imagines himself being secure. But then they hang him from high. He sees the incredible drop below him. Then a general rule imposes itself on his imagination and judgment: heights are dangerous. So here we see that the general rule has force even when there are more rationally-supported judgments that contradict it.

Now let's consider another way to see how a general rule may act against our judgments and imaginations, and how it may in fact reinforce them.

Imagine we slip and almost fall-flat in front of our colleagues. But we catch ourselves before falling completely off our feet. None of them laugh. They are courteous friends. Some make you feel better by saying such things as, "good thing you caught your balance just in time." One person who envies your position says, "God gifted you great grace." It sounds like all the other polite compliments, but you can tell it was an insult by the way he says it. But the general rule tells you that a compliment is well-intentioned. Nonetheless, you still feel burned by his comment.

Now imagine instead that your rival snickered and said, "What a clown!" Then everyone loses composure and breaks out laughing at you. Here the general rule tells you that open insults and mocking laughs are humiliating. As well, your sense-impressions evoke many similar memories of open humiliation. So here we see that the general rule can in fact enhance our imaginations and judgment.

One who lashes me with concealed strokes of satire, moves not my indignation to such a degree, as if he flatly told me I was a fool and coxcomb; tho' I equally understand his meaning, as if he did. This difference is to be attributed to the influence of general rules. (150-151)

§326 Unmasking Our Judgments through Open Insults

When we were insulted openly, there were clear "signs" that told us so: our rival's tone of voice was mocking and our colleagues' laughter could only mean they shared his sentiment. Nonetheless, we still had to "read the signs." We needed to make the inference from sense-impression to the evoked idea of our humiliation. Now consider the alternate case. Here our rival's insult was tacit. But still it was unmistakable. And by looking at everyone else try not to laugh after he make his subtle crack, we could tell they felt the same way.

In both cases we were humiliated. And we inferred that humiliation by reading signs, whether blatant or subtle. What made the difference was only how clear the signs were.

Whether a person openly, abuses me, or slyly intimates his contempt, in neither case do I immediately perceive his sentiment or opinion; and it is only by signs, that is, by its effects, I become sensible of it. The only difference, then, betwixt these two cases consists in this, that in the open discovery of his sentiments he makes use of signs, which are general and universal; and in the secret intimation employs such as are more singular and uncommon. (151a)

But when the signs are more obvious, our imaginations make a more compelling inference.

the imagination, in running from the present impression to the absent idea, makes the transition with greater facility, and consequently conceives the object with greater force, where the connexion is common and universal, than where it is more rare and particular. (151b)

When someone insults us with a hint, we can tell their true feelings. But they are not inclined to openly display those sentiments.

Accordingly we may observe, that the open declaration of our sentiments is called the taking off the mask, as the secret intimation of our opinions is said to be the veiling of them. (151c)

§327 Demonizing Open Insults to Insult Those Who Use Them

Yet, we might prefer that someone openly insults. If they do it tacitly, they can pretend that they meant the insult as a complement. But if they do it openly, then they must face our accusations of their disrespect.

This fact does not contradict the principle which says tacit insults sting less. For indeed direct mockery hurts the most. So society condemns it outright. This serves as a protection. When someone openly insults us, it reflects worse on their character than it does on our own.

§328 The Secret Crimes We Secretly Admit

Hume now considers an analogous phenomenon. [Imagine a small fire is set in a school. The students are evacuated. We decide to take advantage of the situation. So we run-off to the nearby woods to smoke. After a while, the small fire was contained, and school resumes. All the students return to class. But we are late. When we finally enter the classroom, the teacher asks where we were. We say we got lost amidst all the confusion. The teacher suspects we left the school yard intentionally. But given the circumstances, she says she will "let it slide" just this time. For, anything could have happened. Then as we walk past, she smells the smoke on us. Now she thinks she has us, and demands to know where we went to smoke. But we say that the reason we got lost was because we got stuck in a smoky hallway. Again, the teacher just lets it go, even though she is pretty sure we are lying.]

There are wrongs that are unacceptable when performed openly. Yet they are more acceptable when done secretly or when it is difficult to prove they were committed.

Even those, who know with equal certainty, that the fault is committed, pardon it more easily, when the proofs seem in some measure oblique and equivocal, than when they are direct and undeniable. (152c)

So we see that again, our judgment says that the student committed the crime. But the general rule says that in times of chaos, many things go wrong, like getting lost in a cloud of smoke.

§329 Being Tacitly Insulted is Hard Work

When we were openly ridiculed, there was just one sign we were being humiliated: our colleague's laughter. But when their derision was concealed, we noticed many things, like the tone of our rival's voice, our colleague's subtle smirks, and the moments of awkward silence. Any of these alone would not be enough for us to be sure we were being mocked. But altogether they express that fact.

if we compare these two cases, of the open and conceal'd violations of the laws of honour, we shall find, that the difference betwixt them consists in this, that in the first ease the sign, from which we infer the blameable action, is single, and suffices alone to be the foundation of our reasoning and judgment; whereas in the latter the signs are numerous, and decide little or nothing when alone and unaccompanyed with many minute circumstances, which are almost imperceptible. (152d)

So when there is just one sign, we make the inference without any effort. So it is more forceful, and the insult cuts deeper. But when the signs are subtle and plentiful, we have to work hard to conclude with certainty that we are being insulted.

§330 The Cardinal's Cynical Observations Confirm Our Point

Cardinal de Retz' observations confirm these basic principles.

1) Perhaps we are either old or overweight. We would rather people just lie and say we look young or slender. For, "there are many things, in which the world wishes to be deceived." The open statements of fact would cause us to infer too much humiliation.

2) Imagine that a king showed his contempt for us by looking the other way. Now imagine instead he insulted us verbally in front of people we respect. Both send the same message, that the king despises us. But we would be more apt to excuse the king's behavior if he just refused to look at us. For there could be other reasons why someone might do so. Hence "it more easily excuses a person in acting than in talking contrary to the decorum of his profession and character."

§331 Decreasing Degrees of Inferential Intensity

Previously we saw how philosophically admissible inferences still result from habits of association. We assent to one conclusion not so much on rational grounds. Rather, we believe one inference because the idea it evokes is more vivid in our minds.

In this section we examined unphilosophical inferences. We saw that these two types of inference are obtained by the same means.

And also we noted that the strongest evidence is constant conjunction. But usually we encounter other factors that diminish the vivacity of the inference.

But below this degree of evidence there are many others, which have an influence on the passions and imagination, proportioned to that degree of force and vivacity, which they communicate to the ideas. (153d emphasis mine)

We saw that diminishments of inferential force may result when:

a) we have not experienced enough instances to form a strong habit of inference,

b) we encounter contrary effects,

c) resemblances between causes are loose,

d) the present impression is faint or obscure,

e) the previous experiences have faded from memory,

f) the inferential chain has become too long, and

g) the inference is derived from general rules, and these rules lead to inaccurate conclusions.

In all these cases the evidence diminishes by the diminution of the force and intenseness of the idea. (154b emphasis mine)

§332 We May Entrust Our Reasoning to Our Imagination and Senses

But despite these diminishing factors, our arguments are still grounded in evidence. When the prior cases are adulterated by any of the above factors, there is still a way for us come safely to a conclusion. Usually this is based on there being a majority of past experiences that confirm the correct inference.

This contest is at last determin'd to the advantage of that side, where we observe a superior number of these experiments; but still with a diminution of force in the evidence correspondent to the number of the opposite experiments. (154d boldface mine)

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[Directory of other entries in this series.]

From the original text:

Sect. xiii. Of Unphilosophical Probability.
All these kinds of probability are received by philosophers, and allowed to be reasonable foundations of belief and opinion. But there are others, that are derived from the same principles, though they have not had the good fortune to obtain the same sanction. The first probability of this kind may be accounted for thus. The diminution of the union, and of the resemblance, as above explained, diminishes the facility of the transition, and by that means weakens the evidence; and we may farther observe, that the same diminution of the evidence will follow from a diminution of the impression, and from the shading of those colours, under which it appears to the memory or senses. The argument, which we found on any matter of fact we remember, is more or less convincing according as the fact is recent or remote; and though the difference in these degrees of evidence be not received by philosophy as solid and legitimate; because in that case an argument must have a different force to day, from what it shall have a month hence; yet notwithstanding the opposition of philosophy, it is certain, this circumstance has a considerable influence on the understanding, and secretly changes the authority of the same argument, according to the different times, in which it is proposed to us. A greater force and vivacity in the impression naturally conveys a greater to the related idea; and it is on the degrees of force and vivacity, that the belief depends, according to the foregoing system.
There is a second difference, which we may frequently observe in our degrees of belief and assurance, and which never fails to take place, though disclaimed by philosophers. An experiment, that is recent and fresh in the memory, affects us more than one that is in some measure obliterated; and has a superior influence on the judgment, as well as on the passions. A lively impression produces more assurance than a faint one; because it has more original force to communicate to the related idea, which thereby acquires a greater force and vivacity. A recent observation has a like effect; because the custom and transition is there more entire, and preserves better the original force in the communication. Thus a drunkard, who has seen his companion die of a debauch, is struck with that instance for some time, and dreads a like accident for himself: But as the memory of it decays away by degrees, his former security returns, and the danger seems less certain and real.
I add, as a third instance of this kind, that though our reasonings from proofs and from probabilities be considerably different from each other, yet the former species of reasoning often degenerates insensibly into the latter, by nothing but the multitude of connected arguments. It is certain, that when an inference is drawn immediately from an object, without any intermediate cause or effect, the conviction is much stronger, and the persuasion more lively, than when the imagination is carryed through a long chain of connected arguments, however infallible the connexion of each link may be esteemed. It is from the original impression, that the vivacity of all the ideas is derived, by means of the customary transition of the imagination; and it is evident this vivacity must gradually decay in proportion to the distance, and must lose somewhat in each transition. Sometimes this distance has a greater influence than even contrary experiments would have; and a man may receive a more lively conviction from a probable reasoning, which is close and immediate, than from a long chain of consequences, though just and conclusive in each part. Nay it is seldom such reasonings produce any conviction; and one must have a very strong and firm imagination to preserve the evidence to the end, where it passes through so many, stages.
But here it may not be amiss to remark a very curious phaenomenon, which the present subject suggests to us. It is evident there is no point of ancient history, of which we can have any assurance, but by passing through many millions of causes and effects, and through a chain of arguments of almost an immeasurable length. Before the knowledge of the fact coued come to the first historian, it must be conveyed through many mouths; and after it is committed to writing, each new copy is a new object, of which the connexion with the foregoing is known only by experience and observation. Perhaps, therefore, it may be concluded from the precedent reasoning, that the evidence of all ancient history must now be lost; or at least, will be lost in time, as the chain of causes encreases, and runs on to a greater length. But as it seems contrary to common sense to think, that if the republic of letters, and the art of printing continue on the same footing as at present, our posterity, even after a thousand ages, can ever doubt if there has been such a man as JULIUS CAESAR; this may be considered as an objection to the present system. If belief consisted only in a certain vivacity, conveyed from an original impression, it would decay by the length of the transition, and must at last be utterly extinguished: And vice versa, if belief on some occasions be not capable of such an extinction; it must be something different from that vivacity.
Before I answer this objection I shall observe, that from this topic there has been borrowed a very celebrated argument against the Christian Religion; but with this difference, that the connexion betwixt each link of the chain in human testimony has been there supposed not to go beyond probability, and to be liable to a degree of doubt and uncertainty. And indeed it must be confest, that in this manner of considering the subject, (which however is not a true one) there is no history or tradition, but what must in the end lose all its force and evidence. Every new probability diminishes the original conviction; and however great that conviction may be supposed, it is impossible it can subsist under such re-iterated diminutions. This is true in general; though we shall find [Part IV. Sect. 1.] afterwards, that there is one very memorable exception, which is of vast consequence in the present subject of the understanding.
Mean while to give a solution of the preceding objection upon the supposition, that historical evidence amounts at first to an entire proof; let us consider, that though the links are innumerable, that connect any original fact with the present impression, which is the foundation of belief; yet they are all of the same kind, and depend on the fidelity of Printers and Copyists. One edition passes into another, and that into a third, and so on, till we come to that volume we peruse at present. There is no variation in the steps. After we know one we know all of them; and after we have made one, we can have no scruple as to the rest. This circumstance alone preserves the evidence of history, and will perpetuate the memory of the present age to the latest posterity. If all the long chain of causes and effects, which connect any past event with any volume of history, were composed of parts different from each other, and which it were necessary for the mind distinctly to conceive, it is impossible we should preserve to the end any belief or evidence. But as most of these proofs are perfectly resembling, the mind runs easily along them, jumps from one part to another with facility, and forms but a confused and general notion of each link. By this means a long chain of argument, has as little effect in diminishing the original vivacity, as a much shorter would have, if composed of parts, which were different from each other, and of which each required a distinct consideration.
A fourth unphilosophical species of probability is that derived from general rules, which we rashly form to ourselves, and which are the source of what we properly call PREJUDICE. An IRISHMAN cannot have wit, and a Frenchman cannot have solidity; for which reason, though the conversation of the former in any instance be visibly very agreeable, and of the latter very judicious, we have entertained such a prejudice against them, that they must be dunces or fops in spite of sense and reason. Human nature is very subject to errors of this kind; and perhaps this nation as much as any other.
Should it be demanded why men form general rules, and allow them to influence their judgment, even contrary to present observation and experience, I should reply, that in my opinion it proceeds from those very principles, on which all judgments concerning causes and effects depend. Our judgments concerning cause and effect are derived from habit and experience; and when we have been accustomed to see one object united to another, our imagination passes from the first to the second, by a natural transition, which precedes reflection, and which cannot be prevented by it. Now it is the nature of custom not only to operate with its full force, when objects are presented, that are exactly the, same with those to which we have been accustomed; but also to operate in an inferior degree, when we discover such as are similar; and though the habit loses somewhat of its force by every difference, yet it is seldom entirely destroyed, where any considerable circumstances remain the same. A man, who has contracted a custom of eating fruit by the use of pears or peaches, will satisfy himself with melons, where he cannot find his favourite fruit; as one, who has become a drunkard by the use of red wines, will be carried almost with the same violence to white, if presented to him. From this principle I have accounted for that species of probability, derived from analogy, where we transfer our experience in past instances to objects which are resembling, but are not exactly the same with those concerning which we have had experience. In proportion as the resemblance decays, the probability diminishes; but still has some force as long as there remain any traces of the resemblance.
This observation we may carry farther; and may remark, that though custom be the foundation of all our judgments, yet sometimes it has an effect on the imagination in opposition to the judgment, and produces a contrariety in our sentiments concerning the same object. I explain myself. In almost all kinds of causes there is a complication of circumstances, of which some are essential, and others superfluous; some are absolutely requisite to the production of the effect, and others are only conjoined by accident. Now we may observe, that when these superfluous circumstances are numerous, and remarkable, and frequently conjoined with the essential, they have such an influence on the imagination, that even in the absence of the latter they carry us on to t-he conception of the usual effect, and give to that conception a force and vivacity, which make it superior to the mere fictions of the fancy. We may correct this propensity by a reflection on the nature of those circumstances: but it is still certain, that custom takes the start, and gives a biass to the imagination.
To illustrate this by a familiar instance, let us consider the case of a man, who, being hung out from a high tower in a cage of iron cannot forbear trembling, when he surveys the precipice below him, though he knows himself to be perfectly secure from falling, by his experience of the solidity of the iron, which supports him; and though the ideas of fall and descent, and harm and death, be derived solely from custom and experience. The same custom goes beyond the instances, from which it is derived, and to which it perfectly corresponds; and influences his ideas of such objects as are in some respect resembling, but fall not precisely under the same rule. The circumstances of depth and descent strike so strongly upon him, that their influence can-not be destroyed by the contrary circumstances of support and solidity, which ought to give him a perfect security. His imagination runs away with its object, and excites a passion proportioned to it. That passion returns back upon the imagination and inlivens the idea; which lively idea has a new influence on the passion, and in its turn augments its force and violence; and both his fancy and affections, thus mutually supporting each other, cause the whole to have a very great influence upon him.
But why need we seek for other instances, while the present subject of philosophical probabilities offers us so obvious an one, in the opposition betwixt the judgment and imagination arising from these effects of custom? According to my system, all reasonings are nothing but the effects of custom; and custom has no influence, but by inlivening the imagination, and giving us a strong conception of any object. It may, therefore, be concluded, that our judgment and imagination can never be contrary, and that custom cannot operate on the latter faculty after such a manner, as to render it opposite to the former. This difficulty we can remove after no other manner, than by supposing the influence of general rules. We shall afterwards take [Sect. 15.] notice of some general rules, by which we ought to regulate our judgment concerning causes and effects; and these rules are formed on the nature of our understanding, and on our experience of its operations in the judgments we form concerning objects. By them we learn to distinguish the accidental circumstances from the efficacious causes; and when we find that an effect can be produced without the concurrence of any particular circumstance, we conclude that that circumstance makes not a part of the efficacious cause, however frequently conjoined with it. But as this frequent conjunction necessity makes it have some effect on the imagination, in spite of the opposite conclusion from general rules, the opposition of these two principles produces a contrariety in our thoughts, and causes us to ascribe the one inference to our judgment, and the other to our imagination. The general rule is attributed to our judgment; as being more extensive and constant. The exception to the imagination, as being more capricious and uncertain.
Thus our general rules are in a manner set in opposition to each other. When an object appears, that resembles any cause in very considerable circumstances, the imagination naturally carries us to a lively conception of the usual effect, Though the object be different in the most material and most efficacious circumstances from that cause. Here is the first influence of general rules. But when we take a review of this act of the mind, and compare it with the more general and authentic operations of the understanding, we find it to be of an irregular nature, and destructive of all the most established principles of reasonings; which is the cause of our rejecting it. This is a second influence of general rules, and implies the condemnation of the former. Sometimes the one, sometimes the other prevails, according to the disposition and character of the person. The vulgar are commonly guided by the first, and wise men by the second. Mean while the sceptics may here have the pleasure of observing a new and signal contradiction in our reason, and of seeing all philosophy ready to be subverted by a principle of human nature, and again saved by a new direction of the very same principle. The following of general rules is a very unphilosophical species of probability; and yet it is only by following them that we can correct this, and all other unphilosophical probabilities.
Since we have instances, where general rules operate on the imagination even contrary to the judgment, we need not be surprized to see their effects encrease, when conjoined with that latter faculty, and to observe that they bestow on the ideas they present to us a force superior to what attends any other. Every one knows, there is an indirect manner of insinuating praise or blame, which is much less shocking than the open flattery or censure of any person. However be may communicate his sentiments by such secret insinuations, and make them known with equal certainty as by the open discovery of them, it is certain that their influence is not equally strong and powerful. One who lashes me with concealed strokes of satire, moves not my indignation to such a degree, as if he flatly told me I was a fool and coxcomb; though I equally understand his meaning, as if he did. This difference is to be attributed to the influence of general rules.
Whether a person openly, abuses me, or slyly intimates his contempt, in neither case do I immediately perceive his sentiment or opinion; and it is only by signs, that is, by its effects, I become sensible of it. The only difference, then, betwixt these two cases consists in this, that in the open discovery of his sentiments he makes use of signs, which are general and universal; and in the secret intimation employs such as are more singular and uncommon. The effect of this circumstance is, that the imagination, in running from the present impression to the absent idea, makes the transition with greater facility, and consequently conceives the object with greater force, where the connexion is common and universal, than where it is more rare and particular. Accordingly we may observe, that the open declaration of our sentiments is called the taking off the mask, as the secret intimation of our opinions is said to be the veiling of them. The difference betwixt an idea produced by a general connexion, and that arising from a particular one is here compared to the difference betwixt an impression and an idea. This difference in the imagination has a suitable effect on the passions; and this effect is augmented by another circumstance. A secret intimation of anger or contempt shews that we still have some consideration for the person, and avoid the directly abusing him. This makes a concealed satire less disagreeable; but still this depends on the same principle. For if an idea were not more feeble, when only intimated, it would never be esteemed a mark of greater respect to proceed in this method than in the other.
Sometimes scurrility is less displeasing than delicate satire, because it revenges us in a manner for the injury at the very time it is committed, by affording us a just reason to blame and contemn the person, who injures us. But this phaenomenon likewise depends upon the same principle. For why do we blame all gross and injurious language, unless it be, because we esteem it contrary to good breeding and humanity? And why is it contrary, unless it be more shocking than any delicate satire? The rules of good breeding condemn whatever is openly disobliging, and gives a sensible pain and confusion to those, with whom we converse. After this is once established, abusive language is universally blamed, and gives less pain upon account of its coarseness and incivility, which render the person despicable, that employs it. It becomes less disagreeable, merely because originally it is more so; and it is more disagreeable, because it affords an inference by general and common rules, that are palpable and undeniable.
To this explication of the different influence of open and concealed flattery or satire, I shall add the consideration of another phenomenon, which is analogous to it. There are many particulars in the point of honour both of men and women, whose violations, when open and avowed, the world never excuses, but which it is more apt to overlook, when the appearances are saved, and the transgression is secret and concealed. Even those, who know with equal certainty, that the fault is committed, pardon it more easily, when the proofs seem in some measure oblique and equivocal, than when they are direct and undeniable. The same idea is presented in both cases, and, properly speaking, is equally assented to by the judgment; and yet its influence is different, because of the different manner, in which it is presented.
Now if we compare these two cases, of the open and concealed violations of the laws of honour, we shall find, that the difference betwixt them consists in this, that in the first ease the sign, from which we infer the blameable action, is single, and suffices alone to be the foundation of our reasoning and judgment; whereas in the latter the signs are numerous, and decide little or nothing when alone and unaccompanyed with many minute circumstances, which are almost imperceptible. But it is certainly true, that any reasoning is always the more convincing, the more single and united it is to the eye, and the less exercise it gives to the imagination to collect all its parts, and run from them to the correlative idea, which forms the conclusion. The labour of the thought disturbs the regular progress of the sentiments, as we shall observe presently.[Part IV. Sect. 1.] The idea strikes not on us with ouch vivacity; and consequently has no such influence on the passion and imagination.
From the same principles we may account for those observations of the CARDINAL DE RETZ, that there are many things, in which the world wishes to be deceived; and that it more easily excuses a person in acting than in talking contrary to the decorum of his profession and character. A fault in words is commonly more open and distinct than one in actions, which admit of many palliating excuses, and decide not so clearly concerning the intention and views of the actor.
Thus it appears upon the whole, that every kind of opinion or judgment, which amounts not to knowledge, is derived entirely from the force and vivacity of the perception, and that these qualities constitute in the mind, what we call the BELIEF Of the existence of any object. This force and this vivacity are most conspicuous in the memory; and therefore our confidence in the veracity of that faculty is the greatest imaginable, and equals in many respects the assurance of a demonstration. The next degree of these qualities is that derived from the relation of cause and effect; and this too is very great, especially when the conjunction is found by experience to be perfectly constant, and when the object, which is present to us, exactly resembles those, of which we have had experience. But below this degree of evidence there are many others, which have an influence on the passions and imagination, proportioned to that degree of force and vivacity, which they communicate to the ideas. It is by habit we make the transition from cause to effect; and it is from some present impression we borrow that vivacity, which we diffuse over the correlative idea. But when we have not observed a sufficient number of instances, to produce a strong habit; or when these instances are contrary to each other; or when the resemblance is not exact; or the present impression is faint and obscure; or the experience in some measure obliterated from the memory; or the connexion dependent on a long chain of objects; or the inference derived from general rules, and yet not conformable to them: In all these cases the evidence diminishes by the diminution of the force and intenseness of the idea. This therefore is the nature of the judgment and probability.
What principally gives authority to this system is, beside the undoubted arguments, upon which each part is founded, the agreement of these parts, and the necessity of one to explain another. The belief, which attends our memory, is of the same nature with that, which is derived from our judgments: Nor is there any difference betwixt that judgment, which is derived from a constant and uniform connexion of causes and effects, and that which depends upon an interrupted and uncertain. It is indeed evident, that in all determinations, where the mind decides from contrary experiments, it is first divided within itself, and has an inclination to either side in proportion to the number of experiments we have seen and remember. This contest is at last determined to the advantage of that side, where we observe a superior number of these experiments; but still with a diminution of force in the evidence correspondent to the number of the opposite experiments. Each possibility, of which the probability is composed, operates separately upon the imagination; and it is the larger collection of possibilities, which at last prevails, and that with a force proportionable to its superiority. All these phenomena lead directly to the precedent system; nor will it ever be possible upon any other principles to give a satisfactory and consistent explication of them. Without considering these judgments as the effects of custom on the imagination, we shall lose ourselves in perpetual contradiction and absurdity.