As with science, so with medicine. Hubbard's background prior to Dianetics includes nothing at all that would suggest a career focusing on physical and mental (or spiritual) problems. According to the Church of Scientology, Hubbard began the research that led to Dianetics as early as his university days in 1930-32, but there is absolutely no contemporary evidence - for example, in his diaries, which have survived - to suggest that this was the case. Hubbard himself said in Dianetics: The Modern Science of Mental Health that the basic research began in 1935.
The immediate spark for Dianetics is claimed to have been the severe injuries that Hubbard suffered in the Second World War while serving with the US Navy - he claimed years later to have been "blinded with injured optic nerves, and lame with physical injuries to hip and back". [Hubbard, "My Philosophy" (1965) - <http://www.scientology.org/wis-span/EOS/eos_3.htm>] He also claimed to have received shrapnel wounds in the chest, a broken ankle and an eye injury resulting from the muzzle flash of a deck gun, as a result of which he was declared "permanently disabled physically". In fact, as his Veterans Administration file reveals, the worst thing that he suffered from was a duodenal ulcer, plus poor eyesight and bursitis. The ulcer was the principal cause of Hubbard's removal from active service, following a recommendation by his doctors in a report sent to the Commandant of Oak Knoll Naval Hospital on 10 September 1945. Hubbard remained on the reserve list until his final resignation from the Service in October 1950, a few months after Dianetics had made him a brief nationwide celebrity. ["Ron The War Hero" discusses this period of Hubbard's life in more detail - see <http://www.ronthewarhero.org/crippled.htm>] His claims of grievous injuries were largely a later invention. In a December 1950 interview with Look magazine, he explained that he had spent a year in Oak Knoll Naval Hospital suffering from "ulcers, conjunctivitis, deteriorating eyesight, bursitis and something wrong with my feet" ["Dianetics: Science or Hoax?", Look magazine, December 5, 1950 - <http://www.xenu.net/archive/fifties/1950-look.html>] - which pretty much matches what his Veterans Administration doctors had recorded.
Dianetics is based on two fundamental premises: that most physical illnesses are psychosomatic in origin, and that the cause of such psychosomatic ailments is the presence in the human mind of "engrams", or mental recordings of past traumatic incidents. These, in a modified format, are also central tenets of Scientology. Dianetics was specifically intended, from the outset, to effect physical cures, and Hubbard was explicit in saying so:
It contains a therapeutic technique with which can be treated all inorganic mental ills and all organic psychosomatic ills, with assurance of complete cure in unselected cases.
[Hubbard, Dianetics: The Modern Science of Mental Health, 1988 ed., p. 6]
The range of "organic psychosomatic ills" was, in Hubbard's view, far wider than is acknowledged by conventional medical wisdom: "some say, 70% of Man's listed ailments." All of these could be addressed by Dianetics:
Naturally [psychosomatic] diseases, when one has resolved the problem of human aberration, become uniformly susceptible to cure. Arthritis, bursitis, asthma, allergies, sinusitis, coronary trouble, high blood pressure, and so on down the whole catalogue of psycho-somatic ills, adding a few more which were never specifically classified as psycho-somatic, such as the common cold.
[ibid. pp. 109-10]
By "clearing" a person of engrams, it would be possible for a person (or "clear") to effectively become immune to the conditions caused by those engrams:
Clears do not get colds. Just what, if any, part the virus plays in the common cold is not known, but it is known that when engrams about colds are lifted, no further colds appear - which is a laboratory fact not so far contradicted by 270 cases. The common cold comes about, usually, from an engram which suggests it and which is confirmed by actual mucus present in another engram.
Physical attributes could also be modified through the use of Dianetics; the eyes and ears could be "tuned" up and down to greater or lesser levels of sensitivity, and life could be extended (although there wasn't any data to support this, "a hundred years or so from now this data will be available").
[ibid. p. 110]
Hubbard also addressed drugs in Dianetics, claiming that he had found "a workable explanation of the physiological effects of drugs and endocrine substances." [ibid. p. 7] His explanation was that drugs produced a period of "unconsciousness" during which the mind was particularly susceptible to recording traumatic engrams which are mistakenly labeled by the mind as being essential for survival. Drugs (of the medical variety) are ineffective in handling psychosomatic ailments because it is the "aberrated" mind that is producing the illness, not some external organic cause:
Now the reason why various drug preparations which seek to change psycho-somatic illness meet with such uncertain success lies in the fact that the mind, containing these engrams which are [needed for] "survival" (like a fellow needs a hole in his head), handles the life function regulator to actively produce illnesses. Something comes to take them away (they're "survival," you see, and these confounded cells moronically insist upon it) and the mind has to rapidly reverse the activity and put an illness back in place again ...
Feeding a patient with a psycho-somatic ill any number of drugs can result in only temporary relief. "I" doesn't want the illness. The analyzer doesn't want it. But the body has it and if anybody succeeds in curing it short of removing that engram, the body, at the command of the reactive mind, will find something else to substitute for that ill or develop an "allergy" to the drug or annul the effect of the drug entirely.
[ibid. p. 7]
Hubbard made a distinction between purely medical drugs and what he called "hypnotic" drugs, such as pentobarbital, opium and so on. According to Hubbard, such drugs put the mind into a hypnotic condition in which engrams are invariably formed. Ether, chloroform and nitrous oxide were the worst of the lot, as they were used in situations of physical trauma (operating rooms, dentists' surgeries, etc.) Other stimulants had the effect of "exhausting a Q quantity in the mind" - Hubbard had not determined the nature of Q, but he advocated giving all Dianetics "patients" a dose of 10mg of vitamin B1 daily as "reducing engrams exhausts Q which seems to depend in some measure on B1." He returned to this theory of vitamin depletion in Narconon, with the huge overdoses of vitamins and minerals used to compensate for the loss of the "Q quantity".
When Dianetics: The Modern Science of Mental Health was reviewed, it came in for considerable criticism for the many scientific and methodological mistakes that Hubbard made. The lack of hard evidence was a particular sticking point - although Hubbard repeatedly cited "270 cases", no details were ever given of them, despite his claim that "All our facts are functional and these facts are scientific facts, supported wholly and completely by laboratory evidence". He also made many unlikely (indeed, often impossible) claims about amazing cures effected through Dianetics and Scientology, as well as numerous inaccurate statements about medical matters. For instance:
As with Hubbard's scientific claims concerning radiation, his medical claims were the result of ignorance and poor research. His failings were all the more apparent for being present in work which he did personally, rather than being the result of his misunderstanding of someone else's work. When a Board of Inquiry to investigate Scientology was set up in the Australian state of Victoria in the mid-1960s, it produced a concise summary of Hubbard's approach to research:
1. Hubbard is satisfied with, and regards as sufficient, subjective standards of proof;
2. He does not test the data obtained by subjective means even when there are means of objective testing ...
3. He does not give sufficient detail to establish the validity of his conclusions;
4. There is no confirmation of any of his findings by experiments carried out by other workers in the same field;
5. The experiments are not described and there is no way of testing his conclusions;
6. The material which he uses is -
(a) not capable of being tested,
(b) obtained under conditions which do not admit of any control or check,
(c) necessarily suspect for the reasons, amongst others, that it is generally obtained from persons who are hypnotized or who are in some illusory state, and to whom suggestions have frequently been made;
7. A great part of the material relied upon is no more than categorical pronouncements by Hubbard without any suggestion that there is any evidence to justify them;
8. An enormous proportion of Hubbard's so-called evidence, alleged results of experiments, findings and conclusions is totally at variance with orthodox theory and actual known facts which are the results of scientifically conducted experiments made under proper control conditions and capable of being duplicated, tested and confirmed.
[Anderson Report, Chapter 9, "Hubbard's Research" (1965) - <http://www.xenu.net/archive/audit/ar08.html>]
These criticisms are readily verifiable; even a cursory review of Scientology's written materials reveals numerous examples of the failings identified by the Victorian Board. Nor is this problem unique to Scientology; as the section on "Hubbard's Junk Science" reveals, exactly the same problems are apparent in Narconon as well.