COMBINATION OF INDUCTION WITH DEDUCTION
Sec. 1. We have now reviewed Mill's five Canons of Inductive Proof. At
bottom, as he observes, there are only two, namely, Agreement and
Difference: since the Double Method, Variations and Residues are only
special forms of the other two. Indeed, in their function of _proof_,
they are all reducible to one, namely, Difference; for the cogency of
the method of Agreement (as distinguished from a simple enumeration of
instances agreeing in the coincidence of a supposed cause and its
effect), depends upon the omission, in one instance after another, of
all other circumstances; which omission is a point of difference.
The Canons are an analysis of the conditions of proving directly (where
possible), by means of observation or experiment, any proposition that
predicates causation. But if we say 'by means of observation or
experiment,' it is not to be understood that these are the only means
and that nothing else is involved; for it has been shown that the Law of
Causation is itself an indispensable foundation of the evidence. In fact
Inductive Logic may be considered as having a purely formal character.
It consists (1) in a statement of the Law of Cause and Effect; (2) in
certain immediate inferences from this Law, expanded into the Canons;
(3) in the syllogistic application of the Canons to special predications
of causation by means of minor premises, showing that certain instances
satisfy the Canons.
At the risk of some pedantry, we may exhibit the process as follows
(_cf._ Prof. Ray's _Logic_: Appendix D):
Whatever relation of events has certain marks is a case of causation;
The relation A: _p_ has some or all of these marks (as shown
by observation and by the conformity of instances to such or
such a Canon):
Therefore, the relation A: _p_ is a case of causation. Now, the
parenthesis, "as shown by the conformity, etc.," is an adscititious
member of an Epicheirema, which may be stated, as a Prosyllogism, thus:
If an instance, etc. (Canon of Difference);
The instances A B C B C are of the kind required:
_p q r' q r_
Therefore, A, present where _p_ occurs and absent where it
does not occur, is an indispensable antecedent of _p_.
Such is the bare Logic of Induction: so that, strictly speaking,
observation or experiment is no part of the logic, but a means of
applying the logic to actual, that is, not merely symbolical,
propositions. The Formal Logic of Induction is essentially deductive;
and it has been much questioned whether any transition from the formal
to the material conditions of proof is possible. As long as we are
content to illustrate the Canons with symbols, such as A and _p_, all
goes well; but can we in any actual investigation show that the relevant
facts or 'instances' correspond with those symbols?
In the first place, as Dr. Venn shows, natural phenomena want the
distinctness and capability of isolation that belong to symbols.
Secondly, the observing whether instances conform to a Canon, must
always be subject at last to the limits of our faculties. How can we
ascertain exact equality, immediate sequence? The Canon of Difference,
in its experimental application, is usually considered the most cogent
sort of proof: yet when can the two sequent instances, before and after
the introduction of a certain agent, be said to differ in nothing else?
Are not earth and stars always changing position; is not every molecule
in the room and apparatus always oscillating? It is true that our senses
are now aided by elaborate instruments; but the construction of these
depends on scientific theories, which again depend on experiments.
It is right to touch upon this well-known sceptical topic; but to insist
much upon it is not a sign of good sense. The works of Herschel,
Whewell, and Jevons should be consulted for the various methods of
correcting observations, by repeating them, averaging them, verifying
one experimental process by another, always refining the methods of
exact measurement, multiplying the opportunities of error (that if any
exist it may at last show itself), and by other devices of what may be
called Material Logic or Methodology. But only direct experience and
personal manipulation of scientific processes, can give a just sense of
their effectiveness; and to stand by, suggesting academic doubts, is
easier and more amusing.
Sec. 2. Still, it is not so much in laws based upon direct observation or
experiment, that the material validity of scientific reasoning appears,
as in the cumulative evidence that arises from the co-ordination of laws
within each science, and the growing harmony and coherence of all
sciences. This requires a more elaborate combination of deduction with
observation and experiment. During the last three hundred years many
departments of science have been reduced under principles of the
greatest generality, such as the Conservation of Energy, the Law of
Gravitation, the Undulatory theory of Light, the Law of combining
Equivalents, and the Theory of Natural Selection; connecting and
explaining the less general laws, which, again, are said to connect and
explain the facts. Meanwhile, those sciences that were the first to make
progress have helped to develop others which, like Biology and
Sociology, present greater difficulties; and it becomes more and more
apparent that the distinctions drawn among sciences are entirely for the
convenience of study, and that all sciences tend to merge in one
universal Science of Nature. Now, this process of the 'unification of
knowledge' is almost another name for deduction; but at the same time it
depends for its reality and solidity upon a constant reference to
observation and experiment. Only a very inadequate notion of it can be
given in the ensuing chapters.
We saw in chap. xiv. Sec. 6, that when two or more agents or forces combine
to produce a phenomenon, their effects are intermixed in it, and this in
one of two ways according to their nature. In chemical action and in
vegetable and animal life, the causal agents concerned are blended in
their results in such a way that most of the qualities which they
exhibited severally are lost, whilst new qualities appear instead. Thus
chlorine (a greenish-yellow gas) and sodium (a metal) unite to form
common salt NaCl; which is quite unlike either of them: a man eats
bread, and it becomes muscle, nerve and bone. In such cases we cannot
trace the qualities of the causal agents in the qualities of the
effects; given such causes, we can prove experimentally, according to
the canons of induction, that they have such effects; but we may not be
able in any new case to calculate what the effects will be.
On the other hand, in Astronomy and Physics, the causes treated of are
mechanical; at least, it is the aim of Physics to attain to a mechanical
conception of phenomena; so that, in every new combination of forces,
the intermixed effect, or resultant, may be calculated beforehand;
provided that the forces concerned admit of being quantitatively
estimated, and that the conditions of their combination are not so
complex as to baffle the powers of mathematicians. In such cases, when
direct observation or experiment is insufficient to resolve an effect
into the laws of its conditions, the general method is to calculate
what may be expected from a combination of its conditions, as either
known or hypothetically assumed, and to compare this anticipation with
the actual phenomenon.
Sec. 3. This is what Mill calls the Direct Deductive Method; or, the
Physical Method, because it is so much relied on in treating of Light,
Heat, Sound, etc.; it is also the method of Astronomy and much used in
Economics: Deduction leads the way, and its results are tested
inductively by experiments or observations. Given any complex mechanical
phenomenon, the inquirer considers--(1) what laws already ascertained
seem likely to apply to it (in default of known laws, hypotheses are
substituted: _cf._ chap. xviii.); he then--(2) computes the effect that
will follow from these laws in circumstances similar to the case before
him; and (3) he verifies his conclusion by comparing it with the actual
phenomenon.
A simple example of this method is the explanation of the rise of water
in the 'common pump.' We know three laws applicable to this case: (a)
that the atmosphere weighs upon the water outside the pump with a
pressure of 15 lb. to the square inch; (b) that a liquid (and therefore
the water) transmits pressure equally in all directions (upwards as well
as downwards and sideways); and (c) that pressure upon a body in any
direction, if not counteracted by an opposite pressure, produces motion.
Hence, when the rise of the piston of the pump removes the pressure upon
the water within the cylinder, tending to produce a vacuum there, this
water is pushed up by the pressure of the air upon the water outside the
cylinder, and follows the rising piston, until the column of water
inside the cylinder exerts a pressure equal to that of the atmosphere
upon an equal area. So much for the computation; does it correspond with
the fact? It is found that at the sea level water can be pumped to the
height of 33 ft; and that such a column of water has a pressure of 15
lb. to the square inch. We may show further that, at the sea level,
spirits of wine may be pumped higher according to its less specific
gravity; and that if we attempt to pump water at successive altitudes
above the sea level, we can only raise it to less and less heights,
corresponding with the lessened atmospheric pressure at those altitudes,
where the column of air producing the pressure is shorter. Finally, if
we try to work a pump, having first produced a vacuum over the water
outside the cylinder, we shall find that the water inside will not rise
at all; the piston can be raised, but the water does not follow it. The
verification thus shows that the computed effect corresponds with the
phenomenon to be explained; that the result does not depend upon the
nature of water only, but is true (allowing for differences of specific
gravity) of other liquids; that if the pressure of the outside air is
diminished, the height of pumping is so too (canon of Variations); and
that if that pressure is entirely removed, pumping becomes impossible
(canon of Difference).
Any text-book of Astronomy or Physics furnishes numerous illustrations
of the deductive method. Take, for example, the first chapter of
Deschanel's _Optics_, where are given three methods of determining the
velocity of Light. This was first deduced from observation of Jupiter's
satellites. The one nearest the planet passes behind it, or into its
shadow, and is eclipsed, at intervals of about 42-1/2 hours. But it can
be shown that, when Jupiter and the Earth are nearest together on the
same side of the Sun, an eclipse of this satellite is visible from the
earth 16 min. 26.6 sec. earlier than when Jupiter and the earth are
furthest apart on opposite sides of the Sun: 16 min. 26.6 sec, then, is
the time in which light traverses the diameter of the Earth's orbit.
Therefore, supposing the Earth's distance from the Sun to be 92 millions
of miles, light travels about 186,000 miles a second. Another deduction,
agreeing with this, starts from the fact of aberration, or the
displacement of the apparent from the actual position of the stars in
the direction of the earth's motion. Aberration depends partly on the
velocity of light, partly on the velocity of the Earth; and the latter
being known, the former can be computed. Now, these two deductive
arguments, verifying each other, have also been verified experimentally.
Foucault's experiment to measure the velocity of light is too elaborate
to be described here: a full account of it will be found in the treatise
above cited, Sec. 687.
When the phenomena to be explained are of such a character, so vast in
extent, power or duration, that it is impossible, in the actual
circumstances of the case, to frame experiments in order to verify a
deductive explanation, it may still be possible to reproduce a similar
phenomenon upon a smaller scale. Thus Monge's explanation of mirage by
the great heat of the desert sand, which makes the lowest stratum of air
less dense than those above it, so that rays of light from distant
objects are refracted in descending, until they are actually turned
upwards again to the eye of the beholders, giving him inverted images of
the objects as if they were reflected in water, is manifestly incapable
of being verified by experiment in the natural conditions of the
phenomenon. But by heating the bottom of "a sheet-iron box, with its
ends cut away," the rarefied air at the bottom of the box may sometimes
be made to yield reflections; and this shows at least that the supposed
cause is a possible one (Deschanel, _Optics,_ Sec. 726). Similarly as to
the vastest of all phenomena, the evolution of the stellar system, and
of the solar system as part of it, from an immense cloudlike volume of
matter: H. Spencer, in his Essay on _The Nebular Hypothesis_, says,
amidst a great array of deductive arguments from mechanical principles,
that "this _a priori_ reasoning harmonises with the results of
experiment. Dr. Plateau has shown that when a mass of fluid is, as far
as may be, protected from the action of external forces, it will, if
made to rotate with adequate velocity, form detached rings; and that
these rings will break up into spheroids, which turn on their axes in
the same direction with the central mass." The theory of the evolution
of species of plants and animals by Natural Selection, again, though, of
course, it cannot be verified by direct experiment (since experiment
implies artificial arrangement), and the process is too slow for
observation, is, nevertheless, to some extent confirmed by the practice
of gardeners and breeders of animals: since, by taking advantage of
accidental variations of form and colour in the plants or animals under
their care, and relying on the inheritability of these variations they
obtain extensive modifications of the original stocks, and adapt them to
the various purposes for which flowers and cereals, poultry, dogs and
cattle are domesticated. This shows, at least, that living forms are
plastic, and extensively modifiable in a comparatively short time.
Sec. 4. Suppose, however, that, in verifying a deductive argument, the
effect as computed from the laws of the causes assigned, does not
correspond with the facts observed: there must then be an error
somewhere. If the fact has been accurately observed, the error must lie
either in the process of deduction and computation, or else in the
premises. As to the process of deduction, it may be very simple and
easily revised, as in the above explanation of the common pump; or it
may be very involved and comprise long trains of mathematical
calculation. If, however, on re-examining the computations, we find them
correct, it remains to look for some mistake in the premises.
(1) We may not have accurately ascertained the laws, or the modes of
operation, or the amounts of the forces present. Thus, the rate at which
bodies fall was formerly believed to vary in proportion to their
relative weights; and any estimate based upon this belief cannot agree
with the facts. Again, the corpuscular theory of light, namely, that
the physical cause of light is a stream of fine particles projected in
straight lines from the luminous object, though it seemed adequate to
the explanation of many optical phenomena, could not be made to agree
with the facts of interference and double refraction.
(2) The circumstances in which the agents are combined may not have been
correctly conceived. When Newton began to inquire whether the attraction
of the earth determined the orbit of the moon, he was at first
disappointed. "According to Newton's calculations, made at this time,"
says Whewell, "the moon, by her motion in her orbit, was deflected from
the tangent every minute through a space of thirteen feet. But by
noticing the space which bodies would fall in one minute at the earth's
surface, and supposing this to be diminished in the ratio of the inverse
square, it appeared that gravity would, at the moon's orbit, draw a body
through more than fifteen feet." In view of this discrepancy he gave up
the inquiry for sixteen years, until in 1682, having obtained better
data, he successfully renewed it. "He had been mistaken in the magnitude
of the earth, and consequently in the distance of the moon, which is
determined by measurements of which the earth's radius is the base." It
was not, therefore, a mistake as to the law or as to the nature of the
forces concerned (namely, the law of the inverse square and the identity
of celestial with terrestrial gravity), but as to the circumstances in
which the agents (earth and moon) were combined, that prevented his
calculations being verified. (_Hist. Ind. Sc._: VII. ii. 3.)
(3) One or more of the agents affecting the result may have been
overlooked and omitted from the estimate. Thus, an attempt to explain
the tides by taking account only of the earth and the moon, will not
entirely agree with the facts, since the sun also influences the tides.
This illustration, however, shows that when the conclusion of a
deductive explanation does not entirely agree with the facts, it is not
always to be inferred that the reasoning is, properly speaking, wrong;
it may be right as far as it goes, and merely inadequate. Hence (a) in
such cases an opportunity occurs of applying the Method of Residues, by
discovering the agent that must be allowed for in order to complete the
explanation. And (b) the investigation of a phenomenon is often
designedly begun upon an imperfect basis for the sake of simplicity; the
result being regarded as a first approximation, to be afterwards
corrected by including, one by one, the remaining agents or
circumstances affecting the phenomenon, until the theory is complete;
that is, until its agreement with the facts is satisfactory.
(4) We may have included among the data of our reasonings agents or
circumstances that do not exist or do not affect the phenomenon in
question. In the early days of science purely fanciful powers were much
relied upon: such as the solid spheres that carried the planets and
stars; the influence of the planets upon human destiny; the tendency of
everything to seek "its own place," so that fire rises to heaven, and
solids fall to the earth; the "plastic virtue" of the soil, which was
once thought to have produced fossils. When, however, such conceptions
hindered the progress of explanation, it was not so much by vitiating
the deductive method as by putting men off from exact inquiries. More to
our present purpose were the supposed cataclysms, or extraordinary
convulsions of the earth, a belief in which long hindered the progress
of Geology. Again, in Biology, Psychology, and Sociology many
explanations have depended upon the doctrine that any improvement of
structure or faculty acquired by an individual may be inherited by his
descendants: as that, if an animal learns to climb trees, his offspring
have a greater aptitude for that mode of life; that if a man tries to be
good, his children find it easier to be virtuous; that if the
inhabitants of a district carry on cloth-work, it becomes easier for
each successive generation to acquire dexterity in that art. But now the
inheritability of powers acquired by the individual through his own
efforts, is disputed; and, if the denial be made good, all such
explanations as the above must be revised.
If, then, the premises of a deductive argument be vitiated in any of
these four ways, its conclusion will fail to agree with the results of
observation and experiment, unless, of course, one kind of error happen
to be cancelled by another that is 'equal and opposite.' We now come to
a variation of the method of combining Induction with Deduction, so
important as to require separate treatment.
Sec. 5. The Inverse or Historical Method has of late years become
remarkably fruitful. When the forces determining a phenomenon are too
numerous, or too indefinite, to be combined in a direct deduction, we
may begin by collecting an empirical law of the phenomenon (as that 'the
democracies of City-States are arbitrary and fickle'), and then
endeavour to show by deductions from "the nature of the case," that is,
from a consideration of the circumstances and forces known to be
operative (of which, in the above instance, the most important is
sympathetic contagion), that such a law was to be expected. Deduction is
thus called in to verify a previous induction; whereas in the 'Physical
Method' a deduction was verified by comparing it with an induction or an
experiment; hence the method now to be discussed has been named the
Inverse Deductive Method.
But although it is true that, in such inquiries as we are now dealing
with, induction generally takes the lead; yet I cannot think that the
mere order in which the two logical processes occur is the essential
distinction between the two ways of combining them. For, in the first
place, in investigations of any complexity both induction and deduction
recur again and again in whatever order may be most convenient; and, in
the second place, the so-called 'inverse order' is sometimes resorted to
in Astronomy and Physics. For example, Kepler's Laws were first
collected empirically from observations of the planetary motions, and
afterwards deduced by Newton from the Law of Gravitation; this, then,
was the Inverse Method; but the result is something very different from
any that can be obtained by the Historical Method. The essential
difference between the Physical and Historical Methods is that, in the
former, whether Direct or Inverse, the deductive process, when complete,
amounts to exact demonstration; whereas, in the latter, the deductions
may consist of qualitative reasonings, and the results are indefinite.
They establish--(1) a merely probable connection between the phenomena
according to an empirical law (say, between City-democracy and fickle
politics); (2) connect this with other historical or social
generalisations, by showing that they all alike flow from the same
causes, namely, from the nature of races of men under certain social and
geographical conditions; and (3) explain why such empirical laws may
fail, according to the differences that prevail among races of men and
among the conditions under which they live. Thus, seeing how rapidly
excitement is propagated by the chatter, grimacing, and gesticulation of
townsmen, it is probable enough that the democracy of a City-state
should be fickle (and arbitrary, because irresponsible). A similar
phenomenon of panic, sympathetic hope and despair, is exhibited by every
stock-exchange, and is not peculiar to political life. And when
political opinion is not manufactured solely in the reverberating
furnace of a city, fickleness ceases to characterise democracy; and, in
fact, is not found in Switzerland, or the United States, nor in France
so far as politics, depend upon the peasantry.
This is called the Historical Method, then, because it is especially
useful in explaining the movements of history, and in verifying the
generalisations of political and social science. We must not, however,
suppose that its use is confined to such studies. Only a ridiculous
pedantry would allot to each subject its own method and forbid the use
of any other; as if it were not our capital object to establish truth by
any means. Wherever the forces determining a phenomenon are too numerous
or too indefinite to be combined in a deductive demonstration, there the
Historical Method is likely to be useful; and this seems often to be the
case in Geology and Biology, as well as in the Science of History, or
Sociology, and its various subsidiary studies.
Consider upon what causes historical events depend: the customs,
character, and opinions of all the people concerned; the organisation of
their government, and the character of their religious institutions; the
development of industry among them, of the military art, of fine art,
literature and science; their relations, commercial, political and
social, with other nations; the physical conditions of climate and
geographical position amidst which they live. Hardly an event of
importance occurs in any nation that is not, directly or indirectly,
influenced by every one of these circumstances, and that does not react
upon them. Now, from the nature of the Canons of direct Induction, a
satisfactory employment of them in such a complex and tangled situation
as history presents, is rarely possible; for they all require the actual
or virtual isolation of the phenomenon under investigation. They also
require the greatest attainable immediacy of connection between cause
and effect; whereas the causes of social events may accumulate during
hundreds of years. In collecting empirical laws from history, therefore,
only very rough inductions can be hoped for, and we may have to be
content with simple enumeration. Hence the importance of supporting such
laws by deduction from the nature of the case, however faint a
probability of the asserted connection is thereby raised; and this even
if each law is valued merely for its own sake. Still more, if anything
worth the name of Historical Science is to be constructed, must a mere
collection of such empiricisms fail to content us; and the only way to
give them a scientific character is to show deductively their common
dependence upon various combinations of the same causes. Yet even those
who profess to employ the Historical Method often omit the deductive
half of it; and of course 'practical politicians' boast of their entire
contentment with what they call 'the facts.'
Sometimes, however, politicians, venturing upon deductive reasoning,
have fallen into the opposite error of omitting to test their results by
any comparison with the facts: arguing from certain 'Rights of Man,' or
'Interests of Classes,' or 'Laws of Supply and Demand,' that this or
that event will happen, or ought to happen, without troubling themselves
to observe whether it does happen or ever has happened. This method of
Deduction without any empirical verification, is called by Mill the
Geometrical; and, plainly, it can be trustworthy only where there is no
actual conflict of forces to be considered. In pure mathematical
reasoning about space, time, and number, provided the premises and the
reasoning be correct, verification by a comparison with the facts may be
needless, because there is no possibility of counteraction. But when we
deal with actual causes, no computation of their effects can be relied
upon without comparing our conclusions with the facts: not even in
Astronomy and Physics, least of all in Politics.
Burke, then, has well said that "without the guide and light of sound,
well-understood principles all our reasoning in politics, as in
everything else, would be only a confused jumble of particular facts and
details without the means of drawing any sort of theoretical or
practical conclusion"; but that, on the other hand, the statesman, who
does not take account of circumstances, infinite and infinitely
combined, "is not erroneous, but stark mad--he is metaphysically mad"
(_On the Petition of the Unitarians_). There is, or ought to be, no
logical difference between the evidence required by a statesman and that
appealed to by a philosopher; and since, as we have seen, the
combination of principles with circumstances cannot, in solving problems
of social science, be made with the demonstrative precision that belongs
to astronomical and physical investigations, there remains the
Historical Method as above described.
Examples of the empirical laws from which this method begins abound in
histories, newspapers, and political discussions, and are of all shades
of truth or half-truth: as that 'History consists in the biographies of
great men'; in other words, that the movements of society are due to
exceptional personal powers, not to general causes; That at certain
epochs great men occur in groups; That every Fine Art passes through
periods of development, culmination and decline; That Democracies tend
to change into Despotisms; That the possession of power, whether by
classes or despots, corrupts the possessor: That 'the governments most
distinguished for sustained vigour and abilities have generally been
aristocracies'; That 'revolutions always begin in hunger'; That
civilisation is inimical to individuality; That the civilisation of the
country proceeds from the town; That 'the movement of progressive
societies has hitherto been a movement from _Status_ to _Contract_
(i.e., from a condition in which the individual's rights and duties
depend on his caste, or position in his family as slave, child, or
patriarch, to a condition in which his rights and duties are largely
determined by the voluntary agreements he enters into)'; and this last
is treated by H. Spencer as one aspect of the law first stated by Comte,
that the progress of societies is from the military to the industrial
state.
The deductive process we may illustrate by Spencer's explanation of the
co-existence in the military state of those specific characters, the
inductive proof of which furnished an illustration of the method of
Agreement (ch. xvi. Sec. 1). The type of the military State involves the
growth of the warrior class, and the treatment of labourers as existing
solely to support the warriors; the complete subordination of all
individuals to the will of the despotic soldier-king, their property,
liberty and life being at the service of the State; the regimentation of
society, not only for military, but also for civil purposes; the
suppression of all private associations, etc. Now all these
characteristics arise from their utility for the purpose of war, a
utility amounting to necessity if war is the State's chief purpose. For
every purpose is best served when the whole available force co-operates
toward it: other things equal, the bigger the army the better; and to
increase it, men must be taken from industry, until only just enough
remain to feed and equip the soldiers. As this arrangement is not to
everybody's taste, there must be despotic control; and this control is
most effective through regimentation by grades of command. Private
associations, of course, cannot live openly in such a State, because
they may have wills of their own and are convenient for conspiracy. Thus
the induction of characteristics is verified by a deduction of them from
the nature of the case.
Sec. 6. The greater indefiniteness of the Historical compared with the
Physical Method, both in its inductions and in its deductions, makes it
even more difficult to work with. It wants much sagacity and more
impartiality; for the demon of Party is too much with us. Our first care
should be to make the empirical law as nearly true as possible,
collecting as many as we can of the facts which the law is supposed to
generalise, and examining them according to the canons of Induction,
with due allowance for the imperfect applicability of those canons to
such complex, unwieldy, and indefinite instances. In the examples of
such laws given above, it is clear that in some cases no pains have been
taken to examine the facts. What is the inductive evidence that
Democracies change into Despotisms; that revolutions always begin in
hunger; or that civilisation is inimical to individuality? Even Mill's
often quoted saying, "that the governments remarkable in history for
sustained vigour and ability have generally been aristocracies," is
oddly over-stated. For if you turn to the passage (_Rep. Gov._ chap.
vi.), the next sentence tells you that such governments have always been
aristocracies of public functionaries; and the next sentence but one
restricts, apparently, the list of such remarkable governments to
two--Rome and Venice. Whence, then, comes the word "generally" into
Mill's law?
As to deducing our empirical law from a consideration of the nature of
the case, it is obvious that we ought--(a) to take account of all the
important conditions; (b) to allow weight to them severally in
proportion to their importance; and (c) not to include in our estimates
any condition which we cannot show to be probably present and operative.
Thus the Great-Man-Theory of history must surely be admitted to assign a
real condition of national success. The great man organises, directs,
inspires: is that nothing? On the other hand, to recognise no other
condition of national success is the manifest frenzy of a mind in the
mythopoeic age. We must allow the great man his due weight, and then
inquire into the general conditions that (a) bring him to birth in one
nation rather than another, and (b) give him his opportunity.
Mill's explanation of the success of the aristocratic governments of
Rome and Venice is, that they were, in fact, bureaucracies; that is to
say, their members were trained in the science and art of
administration and command. Here, again, we have, no doubt, a real
condition; but is it the only one? The popular mind, which little
relishes the scaling down of Mill's original law to those two remote
cases, is persuaded that an aristocracy is the depository of hereditary
virtue, especially with reference to government, and would at once
ascribe to this circumstance the greater part of the success of any
aristocratic constitution. Now, if the effects of training are
inherited, they must, in an hereditary aristocracy, increase the energy
of the cause assigned by Mill; but, if not, such heredity is a condition
"not present or not operative." Still, if families are ennobled for
their extraordinary natural powers of administration or command (as
sometimes happens), it is agreed on all hands that innate qualities are
inheritable; at least, if care be taken to intermarry with families
similarly distinguished, and if by natural or artificial selection all
the failures among the offspring be eliminated. The Spartans had some
crude notion of both these precautions; and if such measures had been
widely adopted, we might deduce from the doctrine of heredity a
probability in favour of Mill's original proposition, and thereby verify
it in its generality, if it could be collected from the facts.
The Historical Method may be further illustrated by the course adopted
in that branch of Social Science which has been found susceptible of the
most extensive independent development, namely, Economics. First, by way
of contrast, I should say that the abstract, or theoretical treatment of
Economics follows the Physical Method; because, as Mill explains,
although the phenomena of industry are no doubt influenced, like other
social affairs, by all the other circumstances of Society, government,
religion, war, art, etc.; yet, where industry is most developed, as in
England and the United States, certain special conditions affecting it
are so much the most important that, for the purpose at least of a
first outline of the science, they may conveniently be considered as the
only ones. These conditions are: (1) the general disposition of men to
obtain wealth with as little trouble as possible, and (2) to spend it so
as to obtain the greatest satisfaction of their various desires; (3) the
facts that determine population; and (4) the tendency of extractive
industry, when pushed beyond a certain limit without any improvement in
the industrial arts, to yield "diminishing returns." From these premises
it is easy to infer the general laws of prices, of wages and interest
(which are the prices of labour and of the use of capital), and of rent;
and it remains to verify these laws by comparing them with the facts in
each case; and (if they fail to agree with the facts) to amend them,
according to the Method of Residues, by taking account of those
influential conditions which were omitted from the first draft of the
theory.
Whilst, however, this is usually the procedure of those inquirers who
have done most to give Economics its scientific character, to insist
that no other plan shall be adopted would be sheer pedantry; and Dr.
Keynes has shown, in his _Scope and Method of Political Economy_, that
Mill has himself sometimes solved economic problems by the Historical
Method. With an analysis of his treatment of Peasant Proprietorship
(_Political Economy_, B. II., cc. 7 and 8) we may close this section.
Mill first shows inductively, by collecting evidence from Switzerland,
Germany, Norway, Belgium, and France (countries differing in race,
government, climate and situation), that peasant proprietors are
superhumanly industrious; intelligent cultivators, and generally
intelligent men; prudent, temperate, and independent, and that they
exercise self-control in avoiding improvident marriages. This group of
empirical generalisations as to the character of peasant proprietors he
then deduces from the nature of the case: their industry, he says, is a
natural consequence of the fact that, however much they produce, it is
all their own; they cultivate intelligently, because for generations
they have given their whole mind to it; they are generally intelligent
men, because the variety of work involved in small farming, requiring
foresight and calculation, necessarily promotes intelligence; they are
prudent, because they have something to save, and by saving can improve
their station and perhaps buy more land; they are temperate, because
intemperance is incompatible with industry and prudence; they are
independent, because secure of the necessaries of life, and from having
property to fall back upon; and they avoid improvidence in marriage,
because the extent and fertility of their fields is always plainly
before them, and therefore how many children they can maintain is easily
calculated. The worst of them is that they work too hard and deny
themselves too much: but, over the greater part of the world, other
peasantry work too hard; though they can scarcely be said to deny
themselves too much; since all their labour for others brings them no
surplus to squander upon self-indulgence.
Sec. 7. The foregoing account of the Historical Method is based upon Mill's
discussions in B. VI. of his _Logic_, especially cc. 6 to 11. Mill
ascribes to Comte the first clear statement of the method; and it is
highly scientific, and important in generalising the connections of
historical events. But perhaps the expression, 'Historical Method,' is
more frequently applied to the Comparative Method, as used in
investigating the history of institutions or the true sense of legends.
(1) Suppose we are trying to explain the institution of capital
punishment as it now exists in England. (1) We must try to trace the
history of it back to the earliest times; for _social custom and
tradition is one line of causation_. At present the punishment of death
is legally incident only to murder and high treason. But early in the
last century malefactors were hung for forgery, sheep-stealing, arson
and a long list of other offences down to pocket-picking: earlier still
the list included witchcraft and heresy. At present hanging is the only
mode of putting a malefactor to death; but formerly the ways of putting
to death included also burning, boiling, pressing, beheading, and mixed
modes. Before the Restoration, however, the offences punishable with
death were far fewer than they afterwards became; and until the twelfth
century, the penalty of death might be avoided by paying compensation,
the wer-geld.
(2) Every change in the history of an institution must be explained by
pointing to _the special causes_ in operation during the time when the
change was in progress. Thus the restriction of the death penalty, in
the nineteenth century, to so few offences was due partly to the growth
of humane feelings, partly to the belief that the infliction, or threat,
of the extreme penalty had failed to enforce the law and had demoralised
the administration of Justice. The continual extension of the death
penalty throughout the eighteenth century may be attributed to a belief
that it was the most effectual means of deterring evil-doers when the
means of detecting and apprehending criminals were feeble and
ill-organised. The various old brutal ways of execution were adopted
sometimes to strike terror, sometimes for vengeance, sometimes from
horror of the crime, or even from 'conscientious scruples';--which last
were the excuse for preferring the burning of heretics to any sort of
bloodshed.
(3) The causes of any change in the history of an institution in any
country may not be directly discoverable: they must then be investigated
by the Comparative Method. Again, the recorded history of a nation, and
of all its institutions, followed backwards, comes at last to an end:
then the antecedent history must also be supplied by the Comparative
Method; whose special use is to indicate the existence of facts for
which there is no direct evidence.
This method rests upon the principle that where the causes are alike the
effects will be alike, and that similar effects are traceable to similar
causes. Every department of study--Astronomy, Chemistry, Zoology,
Sociology--is determined by the fact that the phenomena it investigates
have certain common characteristics; and we are apt to infer that any
process observed in some of these phenomena, if depending on those
common characteristics, will be found in others. For example, the
decomposition, or radio-activity, of certain elements prepares one to
believe that all elements may exhibit it. Where the properties of an
object are known to be closely interdependent, as in the organisation of
plants, animals and societies, we are especially justified in inferring
from one case to another. The whole animal Kingdom has certain common
characters--the metabolic process, dependence upon oxygen, upon
vegetable food (ultimately), heredity, etc., and, upon this ground, any
process (say, the differentiation of species by Natural Selection) that
has been established for some kinds of animal is readily extended to
others. If instead of the whole animal Kingdom we take some district of
it--Class, Order, Family--our confidence in such inferences increases;
because the common characters are more numerous and the conditions of
life are more alike; or, in other words, the common causes are more
numerous that initiate and control the development of nearly allied
animals. For such reasons a few fragmentary remains of an extinct animal
enable the palaeontologist to reconstruct with some probability an
outline of its appearance, organisation, food, habitat and habits.
Applied to History, the Comparative Method rests upon an assumption
(which the known facts of (say) 6,000 years amply justify) that human
nature, after attaining a recognisable type as _homo sapiens_, is
approximately uniform in all countries and in all ages, though more
especially where states of culture are similar. Men living in society
are actuated by similar motives and reasons in similar ways; they are
all dependent upon the supply of food and therefore on the sun and the
seasons and the weather and upon means of making fire, and so on.
Accordingly, they entertain similar beliefs, and develop similar
institutions through similar series of changes. Hence, if in one nation
some institution has been altered for reasons that we cannot directly
discover, whereas we know the reasons why a similar change was adopted
elsewhere, we may conjecture with more or less probability, after making
allowance for differences in other circumstances, that the motives or
causes in the former case were similar to those in the latter, or in any
cases that are better known. Or, again, if in one nation we cannot trace
an institution beyond a certain point, but can show that elsewhere a
similar institution has had such or such an antecedent history, we may
venture to reconstruct with more or less probability the earlier history
of that institution in the nation we are studying.
Amongst the English and Saxon tribes that settled in Britain, death was
the penalty for murder, and the criminal was delivered to the
next-of-kin of his victim for execution; he might, however, compound for
his crime by paying a certain compensation. Studying the history of
other tribes in various parts of the world, we are able, with much
probability, to reconstruct the antecedents of this death-penalty in our
own prehistoric ages, and to trace it to the blood-feud; that is, to a
tribal condition in which the next-of-kin of a murdered man was socially
and religiously bound to avenge him by slaying the murderer or one of
his kindred. This duty of revenge is sometimes (and perhaps was at first
everywhere) regarded as necessary to appease the ghost of the victim;
sometimes as necessary to compensate the surviving members of his
family. In the latter case, it is open to them to accept compensation in
money or cattle, etc. Whether the kin will be ready to accept
compensation must depend upon the value they set upon wealth in
comparison with revenge; but for the sake of order and tribal strength,
it is the interest of the tribe, or its elders, or chieftain, to
encourage or even to enforce such acceptance. It is also their interest
to take the questions--whether a crime has been committed, by whom, and
what compensation is due--out of the hands of the injured party, and to
submit them to some sort of court or judicial authority. At first,
following ancient custom as much as possible, the act of requital, or
the choice of accepting compensation, is left to the next-of-kin; but
with the growth of central power these things are entrusted to ministers
of the Government. Then revenge has undergone its full transformation
into punishment. Very likely the wrong itself will come to be treated as
having been done not to the kindred of the murdered man, but to the
State or the King, as in fact a "breach of the King's peace." This
happened in our own history.
(4) The Comparative Method assumes that human nature is approximately
the same in different countries and ages; but, of course,
'approximately' is an important word. Although there is often a striking
and significant resemblance between the beliefs and institutions of
widely separated peoples, we expect to draw the most instructive
parallels between those who are nearly related by descent, or
neighbourhood, or culture. To shed light upon our own manners, we turn
first to other Teutons, then to Slavonians and Kelts, or other Aryans,
and so on; and we prefer evidence from Europe to examples from Africa.
(5) As to national culture, that it exhibits certain 'stages' of
development is popularly recognised in the distinction drawn between
savages, barbarians and civilised folk. But the idea remains rather
vague; and there is not space here to define it. I refer, therefore, to
the classifications of stages of culture given by A. Sutherland,
(_Origin and Growth of Moral Instinct_, Vol. I, p. 103), and L.T.
Hobhouse (_Morals in Evolution_, c. 2). That in any 'state of Society,'
its factors--religion, government, science, etc.--are mutually
dependent, was a leading doctrine with Comte, adopted by Mill. There
must be some truth in it; but in some cases we do not understand social
influences sufficiently well to trace the connection of factors; and
whilst preferring to look for historical parallels between nations of
similar culture, we find many cases in which barbarous or savage customs
linger in a civilised country.
(6) It was another favourite doctrine with Comte, also adopted by
Mill--that the general state of culture is chiefly determined by the
prevailing intellectual condition of a people, especially by the
accepted ground of explanation--whether the will of supernatural beings,
or occult powers, or physical antecedents: the "law of three stages,"
Fetichism, Metaphysics, Positivism. And this also is, at least, so far
true, that it is useless to try to interpret the manners and
institutions of any nation until we know its predominant beliefs. Magic
and animism are beliefs everywhere held by mankind in early stages of
culture, and they influence every action of life. But that is not all:
these beliefs retain their hold upon great multitudes of civilised men
and affect the thoughts of the most enlightened. Whilst the saying 'that
human nature is the same in all ages' seems to make no allowance for the
fact that, in some nations, a considerable number of individuals has
attained to powers of deliberation, self-control, and exact reasoning,
far above the barbarous level, it is yet so far true that, even in
civilised countries, masses of people, were it not for the example and
instruction of those individuals, would fall back upon magic and animism
and the manners that go with those beliefs. The different degrees of
enlightenment enjoyed by different classes of the population often
enable the less educated to preserve a barbarous custom amidst many
civilised characteristics of the national life.
Sec. 8. Historical reasoning must start from, or be verified by,
observations. If we are writing the history of ourselves: if of another
time or country, we can observe some of the present conditions of the
country, its inhabitants, language, manners, institutions, which are
effects of the past and must be traceable to it; we may also be able to
observe ancient buildings or their ruins, funerary remains, coins,
dating from the very times we are to treat of. Our own observations, of
course, are by no means free from error.
But even in treating of our own age and country, most of our information
must be derived from the testimony of others, who may have made mistakes
of observation and further mistakes in reporting their observations, or
may have intentionally falsified them. Testimony is of two kinds: Oral;
and Written, inscribed or printed. In investigating the events of a
remote age, nearly all our direct evidence must be some sort of
testimony.
(1) Oral testimony depends upon the character of the witness; and the
best witness is not perfectly trustworthy; for he may not have observed
accurately, or he may not have reported correctly; especially if some
time elapsed between the event and his account of it; for no man's
memory is perfect. Since witnesses vary widely in capacity and
integrity, we must ask concerning any one of them--was he a good judge
of what he saw, and of what was really important in the event? Had he
good opportunities of knowing the circumstances? Had he any interest in
the event--personal, or partisan, or patriotic? Such interests would
colour his report; and so would the love of telling a dramatic story, if
that was a weakness of his. Nay, a love of truth might lead him to
modify the report of what he remembered if--as he remembered it--the
matter seemed not quite credible. We must also bear in mind that, for
want of training, precision in speaking the truth is not understood or
appreciated by many honest people even now, still less in unscientific
ages.
Oral tradition is formed by passing a report from one to another,
generation by generation; and it is generally true that such a tradition
loses credit at every step, because every narrator has some weakness.
However, the value of tradition depends upon the motives people have to
report correctly, and on the form of the communication, and on whether
monuments survive in connection with the story. Amongst the things best
remembered are religious and magic formulae, heroic poems, lists of
ancestors, popular legends about deeply impressive events, such as
migrations, conquests, famines, plagues. We are apt now to underrate the
value of tradition, because the use of writing has made tradition less
important, and therefore less pains are taken to preserve it. In the
middle of last century, it was usual (and then quite justifiable) to
depreciate oral tradition as nearly worthless; but the spread of
archaeological and anthropological research, and the growth of the
Comparative Method, have given new significance to legends and
traditions which, merely by themselves, could not deserve the slightest
confidence.
(2) As to written evidence, contemporary inscriptions--such as are found
on rocks and stones and bricks in various parts of the world, and most
abundantly in Egypt and Western Asia--are of the highest value, because
least liable to fraudulent abuse; but must be considered with reference
to the motives of those who set them forth. Manuscripts and books give
rise to many difficulties. We have to consider whether they were
originally written by some one contemporary with the events recorded: if
so they have the same value as immediate oral testimony, provided they
have not been tampered with since. But if not contemporary records, they
may have been derived from other records that were contemporary, or only
from oral tradition. In the latter case they are vitiated by the
weakness of oral tradition. In the former case, we have to ask what was
the trustworthiness of the original records, and how far do the extant
writings fairly represent those records?
Our answers to these questions will partly depend upon what we know or
can discover of the authors of the MSS. or books. Who was the author? If
a work bears some man's name, did he really write it? The evidence
bearing upon this question is usually divided into internal, external
and mixed; but perhaps no evidence is purely internal, if we define it
as that which is derived entirely from the work itself. Under the name
of internal evidence it is usual to put the language, the style,
consistency of ideas; but if we had no grounds of judgment but the book
itself, we could not possibly say whether the style was the author's:
this requires us to know his other works. Nor could we say whether the
language was that of his age, unless we knew other literature of the
same age; nor even that different passages seem to be written in the
manner of different ages, but for our knowledge of change in other
literatures. There must in every case be some external reference. Thus
we judge that a work is not by the alleged author, nor contemporary with
him, if words are used that only became current at a later date, or are
used in a sense that they only later acquired, or if later writers are
imitated, or if events are mentioned that happened later
('anachronism'). Books are sometimes forged outright, that is, are
written by one man and deliberately fathered upon another; but sometimes
books come to be ascribed to a well-known name, which were written by
some one else without fraudulent intent, dramatically or as a
rhetorical exercise.
As to external evidence, if from other sources we have some knowledge of
the facts described in a given book, and if it presents no serious
discrepancies with those facts, this is some confirmation of a claim to
contemporaneity. But the chief source of external evidence is other
literature, where we may find the book in question referred to or
quoted. Such other literature may be by another author, as when
Aristotle refers to a dialogue of Plato's, or Shakespeare quotes
Marlowe; or may be other work of the author himself, as when Aristotle
in the _Ethics_ refers to his own _Physics_, or Chaucer in _The
Canterbury Tales_ mentions as his own _The Legend of Good Women_, and in
_The Legend_ gives a list of other works of his. This kind of argument
assumes that the authorship of the work we start from is undisputed;
which is practically the case with the _Ethics_ and _The Canterbury
Tales_.
But, now, granting that a work is by a good author, or contemporary with
the events recorded, or healthily related to others that were
contemporary, it remains to consider whether it has been well preserved
and is likely to retain its original sense. It is, therefore, desirable
to know the history of a book or MS., and through whose hands it has
passed. Have there been opportunities of tampering with it; and have
there been motives to do so? In reprinting books, but still more in
copying MSS., there are opportunities of omitting or interpolating
passages, or of otherwise altering the sense. In fact, slight changes
are almost sure to be made even without meaning to make them, especially
in copying MSS., through the carelessness or ignorance of transcribers.
Hence the oldest MS. is reckoned the best.
If a work contains stories that are physically impossible, it shows a
defect of judgment in the author, and decreases our confidence in his
other statements; but it does not follow that these others are to be
rejected. We must try to compare them with other evidence. Even
incredible stories are significant: they show what people were capable
of believing, and, therefore, under what conditions they reasoned and
acted. One cause of the incredibility of popular stories is the fusion
of legend with myth. A legend is a traditionary story about something
that really happened: it may have been greatly distorted by stupidity,
or exaggeration, or dramatisation, or rationalisation, but may still
retain a good deal of the original fact. A myth, however, has not
necessarily any basis of fact: it may be a sort of primitive philosophy,
an hypothesis freely invented to explain some fact in nature, such as
eclipses, or to explain some social custom whose origin is forgotten,
such as the sacrificing of a ram.
All historical conclusions, then, depend on a sum of convergent and
conflicting probabilities in the nature of circumstantial evidence. The
best testimony is only highly probable, and it is always incomplete. To
complete the picture of any past age there is no resource but the
Comparative Method. We use this method without being aware of it,
whenever we make the records of the last generation intelligible to
ourselves by our own experience. Without it nothing would be
intelligible: an ancient coin or weapon would have no meaning, were we
not acquainted with the origins and uses of other coins and weapons.
Generally, the further we go back in history, the more the evidence
needs interpretation and reconstruction, and the more prominent becomes
the appeal to the Comparative Method. Our aim is to construct a history
of the world, and of the planet as part of the world, and of mankind as
part of the life of the planet, in such a way that every event shall be
consistent with, and even required by, the rest according to the
principle of Causation.