He has often been called the Voltaire of the East, and cried down as materialist and atheist.
As regards the first of these two main contentions, it must suffice here to point out the main difficulties in which a determinist and especially materialist account of the relation between consciousness and the organic processes which accompany it appears to be involved.
Science, says the materialist, proves that all known things are material phenomena.
Pessimism is naturally connected with materialist, optimism with idealist, views of life.
So Avenarius (q.v.) was no materialist, but only an empiricist anxious to reclaim man's natural view of the world from philosophic incrustations; yet when his Empiriokriticismus ends in nothing but environment, nervous system, and statements dependent on them, without soul, though within experience, he comes near to materialism, as Wundt has remarked.
Thus, by his enemies, Thorbecke was often held up to scorn as a pure materialist and no friend of the fine arts, because at a sitting of the states-general in 1862 he had said that it is not the duty of the state, nor in the true interest of art itself, for the government to "protect" art, since all state-aided art must be artificial, like any forced plant.
There is no logical connexion between this theory and the doctrine that appetite of desire has always pleasure (or the absence of pain) for its object; but a materialist, framing a system of psychology, will naturally direct his attention to the impulses arising out of bodily wants, whose obvious end is the preservation of the agent's organism; and this, together with a philosophic wish to simplify, may lead him to the conclusion that all human impulses are similarly self-regarding.
It appears also that Darwin, having extended his theory of evolution as far as the rational and moral nature of man, in the Descent of Man, ended in his Autobiography by declaring his attitude to first and final causes to be that of an agnostic. Not that he was a materialist, and shortly before his death, in a conversation with Buchner, he maintained his agnosticism against his opponent's atheism.
Empedocles, Plato and Aristotle; Telesio, Bruno and Campanella; Leibnitz; the idealists, Schopenhauer and Hartmann, Fechner and Paulsen; and the materialist, Haeckel - all have agreed in according some sort of appetition to Nature.
Within this essential co-ordination he distinguished three values: R-values of the environment as stimulus; C-values of the central nervous system; and E-values of human statements - the latter being characterized by that which at the time of its existence for the individual admits of being named, and including what we call sensations, &c., which depend indirectly on the environment and directly on the central nervous system, but are not, as the materialist supposes, in any way reducible to possessions of the brain or any other part of that system.