Editing David Hartley (philosopher) (section)

==Theories==
Like [[John Locke]], he asserted that, prior to sensation, the human mind is a [[blank slate]]. By a growth from simple sensations, those states of consciousness which appear most remote from sensation come into being. And the one law of growth of which Hartley took account was the law of contiguity, synchronous and successive. By this law he sought to explain, not only the phenomena of memory, which others had similarly explained before him, but also the phenomena of emotion, of reasoning, and of voluntary and involuntary action (see [[Association of Ideas]]).<ref name="EB1911">{{EB1911|inline=1|wstitle=Hartley, David|volume=13|page=35}}</ref> A friend, associate, and one of his chief advocates, was [[Joseph Priestley]] (1733–1804), the discoverer of oxygen. Priestley was one of the foremost scientists of his age.

=== Doctrine of vibrations ===
Hartley's physical theory gave birth to the modern study of the intimate connection of physiological and psychical facts. He believed that sensation is the result of a vibration of the minute particles of the [[Medulla oblongata|medulla]]ry substance of the nerves, to account for which he postulated, with [[Isaac Newton|Newton]], a subtle elastic [[Aether (classical element)|ether]], rare in the interstices of solid bodies and in their close neighbourhood, and denser as it recedes from them. Pleasure is the result of moderate vibrations, pain of vibrations so violent as to break the continuity of the nerves. These vibrations leave behind them in the brain a tendency to fainter vibrations or "vibratiuncles" of a similar kind, which correspond to "ideas of sensation." This accounts for memory.<ref name="EB1911"/>

=== Doctrine of associations ===
The course of reminiscence and of the thoughts generally, when not immediately dependent upon external sensation, is accounted for by the idea that there are always vibrations in the brain on account of its heat and the pulsation of its arteries. The nature of these vibrations is determined by each man's past experience, and by the circumstances of the moment, which causes one or another tendency to prevail over the rest. Sensations which are often associated together become each associated with the ideas corresponding to the others; and the ideas corresponding to the associated sensations become associated together, sometimes so intimately that they form what appears to be a new simple idea, not without careful analysis resolvable into its component parts.<ref name="EB1911"/>

=== Free will ===
Starting from a detailed account of the phenomena of the senses, Hartley tried to show how, by the above laws, all the emotions, which he analyses with considerable skill, may be explained. [[John Locke|Locke]]'s phrase "association of ideas" is employed throughout, "idea" being taken as including every mental state but sensation. He emphatically asserts the existence of pure disinterested sentiment, while declaring it to be a growth from the self-regarding feelings. Voluntary action is explained as the result of a firm connexion between a motion and a sensation or "idea," and, on the physical side, between an "ideal" and a motory vibration. Therefore, in the Freewill controversy Hartley took his place as a determinist. It was only with reluctance, and when his speculations were nearly complete, that he came to a conclusion on this subject in accordance with his theory.<ref name="EB1911"/>