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, 'tis 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 'tis 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.
'Tis 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 carried through a long chain of connected arguments,
however infallible the connexion of each link may be esteemed. 'Tis
from the original impression that the vivacity of all the ideas is
derived, 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 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, '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 through so many stages.
But here it may not be amiss to remark a very curious phenomenon which
the present subject suggests to us. 'Tis 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 could 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
increases, 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 Cæsar; 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 confessed, 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, 'tis
impossible it can subsist under such reiterated diminutions. This is
true in general, though we shall find afterwards,[9] that there is one
very memorable exception, which is of vast consequence in the present
subject of the understanding.
Meanwhile, 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 'twere necessary for the
mind distinctly to conceive, 'tis 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, 'tis 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 'tis 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 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 'tis still certain, that
custom takes the start, and gives a bias 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 cannot 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 enlivens 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 enlivening 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[10]
take 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
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.
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. Meanwhile
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 'tis 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 surprised to see their
effects increase, 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 he
may communicate his sentiments by such secret insinuations, and make
them known with equal certainty as by the open discovery of them,
'tis 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
a 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 slily intimates his contempt,
in neither case do I immediately perceive his sentiment or opinion;
and 'tis 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 shows
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 phenomenon 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
'tis 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 case 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 unaccompanied with many minute circumstances, which are almost
imperceptible. But 'tis 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.[11] The idea strikes not
on us with such 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. 'Tis by
habit we make the transition from cause to effect; and 'tis 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. 'Tis indeed evident, that in all determinations where the
mind decides from contrary experiments, 'tis 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 'tis 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.
[9] Part IV. Sect. 1.
[10] Sect. 15.
[11] Part IV. Sect. 1.