Part 11 (1/2)
If, then, the postulate is little certain, we have gained nothing and reach out into the dark; if its certainty is great we no longer have an a.n.a.logy, we have a natural law. Hence, Whately uses the term a.n.a.logy as an expression for the similarity of relation, and in this regard the use of a.n.a.logy for our real work has no special significance. Concerning so-called false a.n.a.logies and their importance cf. J. Schiel's Die Methode der induktiven Forschung (Braunschweig 1868).
Section 28. (f) Probability.
Inasmuch as the work of the criminal judge depends upon the proof of evidence, it is conceivable that the thing for him most important is that which has evidential character or force.[1] A sufficient definition of evidence or proof does not exist because no bounds have been set to the meaning of ”Proved.” All disciplines furnish examples of the fact that things for a long time had probable validity, later indubitable validity; that again some things were considered proved and were later shown to be incorrect, and that many things at one time wobbly are in various places, and even among particular persons, supposed to be at the limits of probability and proof. Es-
pecially remarkable is the fact that the concept of *the proved is very various in various sciences, and it would be absorbing to establish the difference between what is called proved and what only probable in a number of given examples by the mathematician, the physicist, the chemist, the physician, the naturalist, the philologist, the historian, the philosopher, the lawyer, the theologian, etc. But this is no task for us and n.o.body is called upon to determine who knows what ”Proved” means. It is enough to observe that the differences are great and to understand why we criminalists have such various answers to the question: Is this proved or only probable? The varieties may be easily divided into groups according to the mathematical, philosophic, historical or naturalistic inclinations of the answerer. Indeed, if the individual is known, what he means by ”proved” can be determined beforehand. Only those minds that have no especial information remain confused in this regard, both to others and to themselves.
[1] B. Petronievics: Der Satz vom Grunde. Leipzig 1898.
Sharply to define the notion of ”proved” would require at least to establish its relation to usage and to say: What we desire leads us to an *a.s.sumption, what is possible gives us *probability, what appears certain, we call *proved. In this regard the second is always, in some degree, the standard for the first (desires, e. g., cause us to act; one becomes predominant and is fixed as an a.s.sumption which later on becomes clothed with a certain amount of reliability by means of this fixation).
The first two fixations, the a.s.sumption and the probability, have in contrast to their position among other sciences only a heuristic interest to us criminalists. Even a.s.sumptions, when they become hypotheses, have in various disciplines a various value, and the greatest lucidity and the best work occur mainly in the quarrel about an acutely constructed hypothesis.
*Probability has a similar position in the sciences. The scholar who has discovered a new thought, a new order, explanation or solution, etc., will find it indifferent whether he has made it only highly probable or certain. He is concerned only with the idea, and a scholar who is dealing with the idea for its own sake will perhaps prefer to bring it to a great probability rather than to indubitable certainty, for where conclusive proof is presented there is no longer much interest in further research, while probability permits and requires further study. But our aim is certainty and proof only, and even a high degree of probability is no better than untruth and can not count. In pa.s.sing judgment and for the purpose of judgment
a high degree of probability can have only corroborative weight, and then it is probability only when taken in itself, and proof when taken with regard to the thing it corroborates. If, for example, it is most probable that X was recognized at the place of a crime, and if at the same time his evidence of alibi has failed, his footmarks are corroborative; so are the stolen goods which have been seen in his possession, and something he had lost at the place of the crime which is recognized as his property, etc. ln short, when all these indices are in themselves established only as highly probable, they give under certain circ.u.mstances, when taken together, complete certainty, because the coincidence of so many high probabilities must be declared impossible if X were not the criminal.
In all other cases, as we have already pointed out, *a.s.sumption and probability have only a heuristic value for us lawyers. With the a.s.sumption, we must of course count; many cases can not be begun without the a.s.sistance of a.s.sumption. Every only half- confused case, the process of which is unknown, requires first of all and as early as possible the application of some a.s.sumption to its material. As soon as the account is inconsistent the a.s.sumption must be abandoned and a fresh one and yet again a fresh one a.s.sumed, until finally one holds its own and may be established as probable. It then remains the center of operation, until it becomes of itself a proof or, as we have explained, until so many high probabilities in various directions have been gathered, that, taken in their order, they serve evidentially. A very high degree of probability is sufficient in making complaints; but sentencing requires ”certainty,” and in most cases the struggle between the prosecution and the defense, and the doubt of the judge, turns upon the question of probability as against proof.[1]
[1] Of course we mean by ”proof” as by ”certainty” only the highest possible degree of probability.
That probability is in this way and in a number of relations, of great value to the criminalist can not appear doubtful. Mittermaier defines its significance briefly: ”Probability naturally can never lead to sentence. It is, however, important as a guide for the conduct of the examiner, as authorizing him to take certain measures; it shows how to attach certain legal processes in various directions.”
Suppose that we review the history of the development of the theory of probability. The first to have attempted a sharp distinction between demonstrable and probable knowledge was Locke. Leibnitz was the first to recognize the importance of the theory
of probability for inductive logic. He was succeeded by the mathematician Bernoulli and the revolutionist Condorcet. The theory in its modern form was studied by Laplace, Quetelet, Herschel, von Kirchmann, J. von Kries, Venn, Cournot, Fick, von Bortkiewicz, etc. The concept that is called probability varies with different authorities. Locke[1] divides all fundamentals into demonstrative and probable. According to this cla.s.sification it is probable that ”all men are mortal,” and that ”the sun will rise to-morrow.” But to be consistent with ordinary speech the fundamentals must be cla.s.sified as evidence, certainties, and probabilities. By certainties I understand such fundamentals as are supported by experience and leave no room for doubt or consideration-everything else, especially as it permits of further proof, is more or less probable.
[1] Locke: Essay on the Human Understanding.
Laplace[2] spoke more definitely-”Probability depends in part on our ignorance, in part on our knowledge ...
[2] Laplace: Essay Philosophique sur les Probabilit'>s. Paris 1840.
”The theory of probability consists in the reduction of doubts of the same cla.s.s of a definite number of equally possible cases in such a way that we are equally undetermined with regard to their existence, and it further consists in the determination of the number of those cases which are favorable to the result the probability of which is sought. The relation of this number to the number of all possible cases is the measure of the probability. It is therefore a fraction the numerator of which is derived from the number of cases favorable to the result and the denominator from the number of all possible cases.” Laplace, therefore, with J. S. Mill, takes probability to be a low degree of certainty, while Venn[3] gives it an objective support like truth. The last view has a great deal of plausibility inasmuch as there is considerable doubt whether an appearance is to be taken as certain or as only probable. If this question is explained, the a.s.sertor of certainty has a.s.sumed some objective foundation which is indubitable at least subjectively. Fick represents the establishment of probability as a fraction as follows: ”The probability of an incompletely expressed hypothetical judgment is a real fraction proved as a part of the whole universe of conditions upon which the realization of the required result necessarily depends.
[3] Venn: The Logic of Chance.
”According to this it is hardly proper to speak of the probability of any result. Every individual event is either absolutely necessary
or impossible. The probability is a quality which can pertain only to a hypothetical judgment.”[1]
[1] Philos. Versuch <u:>ber die Wahrscheinlichkeiten. W<u:>rzburg 1883.
That it is improper to speak of the probability of a result admits of no doubt, nor will anybody a.s.sert that the circ.u.mstance of to- morrow's rain is in itself probable or improbable-the form of expression is only a matter of usage. It is, however, necessary to distinguish between conditioned and unconditioned probability. If I to-day consider the conditions which are attached to the ensuing change of weather, if I study the temperature, the barometer, the cloud formation, the amount of sunlight, etc., as conditions which are related to to-morrow's weather as its forerunners, then I must say that to-morrow's rain is probable to such or such a degree. And the correctness of my statement depends upon whether I know the conditions under which rain *must appear, more or less accurately and completely, and whether I relate those conditions properly. With regard to unconditioned probabilities which have nothing to do with the conditions of to-day's weather as affecting to-morrow's, but are simply observations statistically made concerning the number of rainy days, the case is quite different. The distinction between these two cases is of importance to the criminalist because the subst.i.tution of one for the other, or the confusion of one with the other, will cause him to confuse and falsely to interpret the probability before him. Suppose, e. g., that a murder has happened in Vienna, and suppose that I declare immediately after the crime and in full knowledge of the facts, that according to the facts, i. e., according to the conditions which lead to the discovery of the criminal, there is such and such a degree of probability for this discovery. Such a declaration means that I have calculated a conditioned probability. Suppose that on the other hand, I declare that of the murders occurring in Vienna in the course of ten years, so and so many are unexplained with regard to the personality of the criminal, so and so many were explained within such and such a time,-and consequently the probability of a discovery in the case before us is so and so great. In the latter case I have spoken of unconditioned probability. Unconditioned probability may be studied by itself and the event compared with it, but it must never be counted on, for the positive cases have already been reckoned with in the unconditioned percentage, and therefore should not be counted another time. Naturally, in practice, neither form of probability is frequently calculated in figures; only an approximate
interpretation of both is made. Suppose that I hear of a certain crime and the fact that a footprint has been found. If without knowing further details, I cry out: ”Oh! Footprints bring little to light!” I have thereby a.s.serted that the statistical verdict in such cases shows an unfavorable percentage of unconditional probability with regard to positive results. But suppose that I have examined the footprint and have tested it with regard to the other circ.u.mstances, and then declared: ”Under the conditions before us it is to be expected that the footprint will lead to results”- then I have declared, ”According to the conditions the conditioned probability of a positive result is great.” Both a.s.sertions may be correct, but it would be false to unite them and to say, ”The conditions for results are very favorable in the case before us, but generally hardly anything is gained by means of footprints, and hence the probability in this case is small.” This would be false because the few favorable results as against the many unfavorable ones have already been considered, and have already determined the percentage, so that they should not again be used.
Such mistakes are made particularly when determining the complicity of the accused. Suppose we say that the manner of the crime makes it highly probable that the criminal should be a skilful, frequently-punished thief, i. e., our probability is conditioned. Now we proceed to unconditioned probability by saying: ”It is a well-known fact that frequently-punished thieves often steal again, and we have therefore two reasons for the a.s.sumption that X, of whom both circ.u.mstances are true, was the criminal.” But as a matter of fact we are dealing with only one identical probability which has merely been counted in two ways. Such inferences are not altogether dangerous because their incorrectness is open to view; but where they are more concealed great harm may be done in this way.
A further subdivision of probability is made by Kirchmann.[1]
He distinguished: [1] <u:>ber die Wahrscheinlicbkeit, Leipzig 1875.
(1) General probability, which depends upon the causes or consequences of some single uncertain result, and derives its character from them. An example of the dependence on causes is the collective weather prophecy, and of dependence on consequences is Aristotle's dictum, that because we see the stars turn the earth must stand still. Two sciences especially depend upon such probabilities: history and law, more properly the practice and use of criminal
law. Information imparted by men is used in both sciences, this information is made up of effects and hence the occurrence is inferred from as cause.
(2) Inductive probability. Single events which must be true, form the foundation, and the result pa.s.ses to a valid universal. (Especially made use of in the natural sciences, e. g., in diseases caused by bacilli; in case X we find the appearance A and in diseases of like cause Y and Z, we also find the appearance A. It is therefore probable that all diseases caused by bacilli will manifest the symptom A.)
(3) Mathematical Probability. This infers that A is connected either with B or C or D, and asks the degree of probability. I. e.: A woman is brought to bed either with a boy or a girl: therefore the probability that a boy will be born is one-half.
Of these forms of probability the first two are of equal importance to us, the third rarely of value, because we lack arithmetical cases and because probability of that kind is only of transitory worth and has always to be so studied as to lead to an actual counting of cases. It is of this form of probability that Mill advises to know, before applying a calculation of probability, the necessary facts, i. e., the relative frequency with which the various events occur, and to understand clearly the causes of these events. If statistical tables show that five of every hundred men reach, on an average, seventy years, the inference is valid because it expresses the existent relation between the causes which prolong or shorten life.
A further comparatively self-evident division is made by Cournot, who separates subjective probability from the possible probability pertaining to the events as such. The latter is objectively defined by Kries[1] in the following example: