‘‘Whenever we have reason to trust earlier experiences and to take them as standards of judgment of future experiences； these reasons may have probability。''
The place of probability in the positive determination of the order of modern criminal procedure is not insignificant。 When the law determines upon a definite number of jurymen or judges； it is probable that this number is sufficient for the discovery of the truth。 The system of prosecution establishes as a probability that the accused is the criminal。 The idea of time…lapse assumes the probability that after the passage of a certain time punishment becomes illusory； and prosecution uncertain and difficult。 The institution of experts depends on the probability that the latter make no mistakes。 The warrant for arrest depends on the probability that the accused behaved suspiciously or spoke of his crime； etc。 The oath of the witness depends on the probability that the witness will be more likely to tell the truth under oath； etc。
Modern criminal procedure involves not only probabilities but also various types of possibility。 Every appeal has for its foundation the possibility of an incorrect judgment； the exclusion of certain court officials is based on the possibility of prejudice； or at least on the suspicion of prejudice； the publicity of the trial is meant to prevent the possibility of incorrectness； the revision of a trial depends on the possibility that even legal sentences may be false and the institution of the defendant lawyer depends upon the possibility that a person without defense may receive injustice。 All the formalities of the action of the court assume the possibility that without them improprieties may occur； and the institution of seizing letters and messages for evidence； asserts only the possibility that the latter contain things of importance； etc。
When the positive dicta of the law deal with possibility and proba… bility in questions of great importance the latter become especially significant。
We have yet to ask what is meant by ‘‘rule'' and what its relation is to probability。 Scientifically ‘‘rule'' means law subjectively taken and is of equal significance with the guiding line for one's own conduct； whence it follows that there are only rules of art and morality； but no rules of nature。 Usage does not imply this interpretation。 We say that as a rule it hails only in the daytime； by way of exception； in the night also； the rule for the appearance of whales indicates that they live in the Arctic Ocean； a general rule indicates that bodies that are especially soluble in water should dissolve more easily in warm than in cold water； but salt dissolves equally well in both。 Again we say： As a rule the murderer is an unpunished criminal； it is a rule that the brawler is no thief and vice versa； the gambler is as a rule a man of parts； etc。 We may say therefore； that regularity is equivalent to customary recurrence and that whatever serves as rule may be expected as probable。 If； i。 e。； it be said； that this or that happens as a rule； we may suppose that it will repeat itself this time。 It is not permissible to expect more； but it frequently happens that we mistake rules permitting exceptions for natural laws permitting none。 This occurs frequently when we have lost ourselves in the regular occurrences for which we are ourselves responsible and suppose that because things have been seen a dozen times they must always appear in the same way。 It happens especially often when we have heard some phenomenon described in other sciences as frequent and regular and then consider it to be a law of nature。 In the latter case we have probably not heard the whole story； nor heard general validity assigned to it。 Or again； the whole matter has long since altered。 Lotze wrote almost half a century ago； that he had some time before made the statistical observation that the great positive discoveries of exact physiology have an average life of about four years。 This noteworthy statement indicates that great positive discoveries are set up as natural laws only to show themselves as at most regular phenomena which have no right to general validity。 And what is true of physiology is true of many other sciences； even of the great discoveries of medicine； even legal medicine。 This； therefore； should warn against too much confidence in things that are called ‘‘rules。'' False usage and comfortable dependence upon a rule have very frequently led us too far。 Its unreliability is shown by such maxims as ‘‘Three misses make a rule'' or ‘‘Many stupidities taken together give a golden rule of life；'' or ‘‘To…day's exception is to…morrow's rule；'' or the classical perversion： ‘‘The rule that there are no rules without exception is a rule without exception； hence； there is one rule without exception。''
The unreliability of rules is further explained by their rise from generalization。 We must not generalize； as Schiel says； until we have shown that if there are cases which contradict our generalizations we know those contradictions。 In practice approximate generalizations are often our only guides。 Natural law is too much conditioned； cases of it too much involved； distinctions between them too hard to make； to allow us to determine the existence of a natural phenomenon in terms of its natural characteristics as a part of the business of our daily life。 Our own age generalizes altogether too much； observes too little； and abstracts too rapidly。 Events come quickly； examples appear in masses； and if they are similar they tend to be generalized； to develop into a rule； while the exceptions which are infinitely more important are unobserved； and the rule； once made； leads to innumerable mistakes。
Section 29。 （g） Chance。
The psychological significance of what we call chance depends upon the concept of chance and the degree of influence that we allow it to possess in our thinking。 What is generally called chance； and what is called chance in particular cases； will depend to a significant degree upon the nature of the case。 In progressive sciences the laws increase and the chance…happenings decrease； the latter indeed are valid only in particular cases of the daily life and in the general business of it。 We speak of chance or accident when events cross which are determined in themselves by necessary law； but the law of the crossing of which is unknown。 If； e。 g。； it is observed that where there is much snow the animals are white； the event must not be attributed to accident； for the formation of snow in high mountains or in the north； and its long stay on the surface of the earth develop according to special natural laws； and the colors of animals do so no lessbut that these two orderly series of facts should meet requires a third law； or still better； a third group of laws； which though unknown some time ago； are now known to every educated person。
For us lawyers chance and the interpretation of it are of immense importance not only in bringing together evidence； but in every case of suspicion； for the problem always arises whether a causal relation may be established between the crime and the suspect； or whether the relation is only accidental。 ‘‘Unfortunate coincidence'' ‘‘closely related connection of facts''‘‘extraordinary accumulation of reason for suspicion；''all these terms are really chance mistaken for causation。 On the knowledge of the difference between the one and the other depends the fate of most evidence and trials。 Whoever is fortunate enough in rightly perceiving what chance is； is fortunate in the conduct of his trial。
Is there really a theory of chance？ I believe that a direct treatment of the subject is impossible。 The problem of chance can be only approximately explained when all conceivable chance…happenings of a given discipline are brought together and their number reduced by careful search for definite laws。 Besides； the problem demands the knowledge of an extremely rich casuistry； by means of which； on the one hand； to bring together the manifoldness of chance events； and on the other to discover order。 Enough has been written about chance； but a systematic treatment of it must be entirely theoretical。 So Windelband's＇1＇ excellent and well…ordered book deals with relations （chance and cause； chance and law； chance and purpose； chance and concept） the greatest value of which is to indicate critically the various definitions of the concept of chance。 Even though there is no definition which presents the concept of chance in a completely satisfactory manner； the making of such definitions is still of value because one side of chance is explained and the other is thereby seen more closely。 Let us consider a few of these and other definitions。 Aristotle says that the accidental occurs； ； according to nature。 Epicurus； who sees the creation of the world as a pure accident； holds it to occur 。 Spinoza believes nothing to be contingent save only according to the limitations of knowledge； Kant says that conditioned existence as such； is called accidental； the unconditioned； necessary。 Humboldt： ‘‘Man sees those things as accident which he can not explain genetically。'' Schiel： ‘‘Whatever may not be reduced back to law is called accidental。'' Quetelet： ‘‘The word chance serves officiously to hide our ignorance。'' Buckle derives the idea of chance from the life of nomadic tribes； which contains nothing firm and regulated。 According to Trendelenburg chance is that which could not be otherwise。 Rosenkranz says： Chance is a reality which has only the value of possibility； while Fischer calls chance the individualized fact； and Lotze identifies it with everything that is not valid as a natural purpose。 For Windelband ‘‘chance consists； according to usage； in the merely factual but not necessary transition from a possibility to an actuality。 Chance is the negation of necessity。 It is a contradiction to say ‘This happened by accident；' for the word ‘by' expressed a cause。''
＇1＇ Windelband： Die Lehren vom Zufall。 Berlin 1870。
A。 Hfler＇1＇ says most intelligently； that the contradiction of the idea of chance by the causal law may be easily solved by indicating the especia