The article on Liberty would be extremely remarkable, appearing where it does, and coming from a thinker of Diderot’s general capacity, if only we could be sure that Diderot was sincere.  As it happens, there is good reason to suppose that he was wholly insincere.  It is quite as shallow, from the point of view of philosophy, as his article on the Jews or on the Bible is from the point of view of erudition.  One reason for this might not be far to seek.  We have repeatedly observed how paramount the social aim and the social test are in Diderot’s mind over all other considerations.  But this reference of all subjects of discussion to the good of society, and this measurement of conclusions by their presumed effect on society, is a method that has its own dangers.  The aversion of ecclesiastics to unfettered discussion, lest it should damage institutions and beliefs deemed useful to mankind, is the great leading example of this peril.  Diderot, it might be said by those who should contend that he wrote what he thought, did not escape exactly the same predicament, as soon as ever he forgot that of all the things that are good for society, Truth is the best.  Now, who will believe that it is Diderot, the persecuted editor of the Encyclopaedia, and the author of the manly article on Intolerance, who introduces such a passage as the following into the discussion of the everlasting controversy of Free Will and Necessity:  “Take away Liberty, and you leave no more vice nor virtue nor merit in the world; rewards are ridiculous, and punishments unjust.  The ruin of Liberty overthrows all order and all police, confounds vice and virtue, authorises every monstrous infamy, extinguishes the last spark of shame and remorse, degrades and disfigures beyond recovery the whole human race. A doctrine of such enormity as this ought not to be examined in the schools; it ought to be punished by the magistrates."[187] Of course, this was exactly what the Jesuits said about a belief in God, about revelation, and about the institutions of the church.  To take away these, they said, is to throw down the bulwarks of order, and an attempt to take them away, as by encyclopaedists or others, ought to be punished by the magistrates.  Diderot had for the moment clearly lost himself.

We need hardly be surprised if an article conceived in this spirit contains no serious contribution to the difficult question with which it deals.  Diderot had persuaded himself that, without Free Will, all those emotional moralities in the way of sympathy and benevolence and justice which he adored would be lowered to the level of mere mechanism.  “If men are not free in what they do of good and evil, then,” he cries, in what is surely a paroxysm of unreason, “good is no longer good, and evil no longer evil.”  As if the outward quality and effects of good and evil were not independent of the mental operations which precede human action.  Murder would not cease to be an evil simply because it had