Sequence which is the more known in ordine ad hominem in the case of the causal principle differs from merely psychological conviction is not made fully clear.
Nevertheless he believes that, when we can apply measures to the combination of empirical appearances, then we can apply the logical principle as causal law to this combination, and say that one appearance is the cause of another, thus adding a notion of causality not contained in the actual observations, but specializing the general notion of causality.
In the mechanical processes which we can experimentally modify at will, and which therefore we learn to apprehend with greatest fulness, whenever an effect on a body, B, is in causal connexion with a process instituted in another body, A, it is usually possible to discover a mechanical connexion between the two bodies which allows the influence of A to be traced all the way across the intervening region.
In this way conditions formerly believed to be the causes of disease are now recognized as playing their part in predisposing to the action of the true causal agent, viz.
Nature as a machine, governed by changeless causal law, is necessary to thought.
The nerve of proof in the processes by which he establishes causal conjunctions of unlimited application is naturally thought to lie in the special canons of the several processes and the axioms of universal and uniform causation which form their background.
It is possible to understand that Napoleon had power and so events occurred; with some effort one may even conceive that Napoleon together with other influences was the cause of an event; but how a book, Le Contrat Social, had the effect of making Frenchmen begin to drown one another cannot be understood without an explanation of the causal nexus of this new force with the event.
The mistake of earlier advocates of determinism lay in the supposition that self-conscious moral action could be explained by the use of the same categories and upon the same hypotheses usually considered sufficient to explain the causal sequences observable in the physical world.
Motions do not cause motions; one body moving causes another body to move: what we know is causal substances.
Determined sequence is the causal relation in any possible experience, and no experience is possible save through the determination of perceived changes as in relation to a determined order in time.