Criminal Psychology by Hans Gross (best book recommendations .TXT) 📕

Concerning so-called false analogies 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-

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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 nobody 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 *assumption, 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 assumption which later on becomes clothed with a certain amount of reliability by means of this fixation).

The first two fixations, the assumption and the probability, have in contrast to their position among other sciences only a heuristic interest to us criminalists. Even assumptions, 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 passing judgment and for the purpose of judgment <p 149>

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 circumstances, 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, *assumption

and probability have only a heuristic value for us lawyers. With the assumption, we must of course count; many cases can not be begun without the assistance of assumption. Every only half-confused case, the process of which is unknown, requires first of all and as early as possible the application of some assumption to its material. As soon as the account is inconsistent the assumption must be abandoned and a fresh one and yet again a fresh one assumed, 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 <p 150>

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 classification 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 classified 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<e’>s. Paris 1840.

“The theory of probability consists in the reduction of doubts of the same class 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 assertor of certainty has assumed 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 <p 151>

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 assert that the circumstance 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 substitution 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 <p 152>

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 asserted 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 circumstances, and then declared: “Under the conditions before us it is to be expected that the footprint will lead