That is to say, criminal justice should be based on the neglect of the elementary rule of justice, according to which every man ought always to consider the possible consequences of his actions. And the criminal law demands from juries this proof of their blindness (which is fortunately impossible) that they should judge blindfold, with no regard for the prisoner, or for the consequences which their verdict may have upon him.
It was impossible that the advocates of the jury should fail to see the absurdity of these principles; and they have been compelled to slur them over, at any rate in ordinary practice.
In respect of the composition of juries, restrictions have been introduced, by means of lists of eligible persons, selection by lot, the optional exclusion of a certain number of jurymen by the public prosecutor and the defence, &c. All these expedients, however, some of which are imposed by necessity, can only insure a general and presumptive capacity, for they have the merely negative effect of contributing to exclude the most manifest moral or intellectual incapacity. But the only capacity which is necessary in a judge, which is a special and positive capacity, is not guaranteed by these restrictions, which, after all, are a negation of the very principle of the jury.
And even if the jury were always composed of persons of adequate capacity, it would still be condemned by two inevitable arguments of human psychology.
First, the assembling of several individuals of typical capacity never affords a guarantee of collective capacity, for in psychology a meeting of individuals is far from being equivalent to the aggregate of their qualities. As in chemistry the combination of two gases may give us a liquid so in psychology the assembling of individuals of good sense may give us a body void of good sense. This is a phenomenon of psychological fermentation, by which individual dispositions, the least good and wise, that is the most numerous and effective, dominate the better ones, as the rule dominates the exceptions. This explains the ancient saying, ``The senators are good men, but the Senate is a mischievous animal.''
And this fact of collective inferiority, not to say degeneracy, is observed in casual assemblies, such as juries, meetings, and the like, far more than in organised and permanent councils of judges, experts, &c.
Secondly, the jury, even when composed of persons of average capacity, will never be able in its judicial function to follow the best rules of intellectual evolution.
Human intelligence, in fact, both individual and collective, displays these three phases of progressive development: common sense, reason, and science, which are not essentially different, but which differ greatly in the degree of their complexity. Now it is evident that a gathering of individuals of average capacity, but not technical capacity, will in its decisions only be able to follow the rules of common sense, or at most, by way of exception, the rules of reason--that is, of their common mental habits, more or less directed by a certain natural capacity. But the higher rules of science, which are still indispensable for a judgment so difficult as that which bears on crimes and criminals, will always be unknown to it.