In that vein, let me tell you a story. It's 1991, I am flying home from Germany, sitting next to a man who is almost in tears, he is so upset. He's a physician involved in an FDA study of a new drug. It's a double-blind study involving four separate teams---one plans the study, another administers the drug to patients, a third assesses the effect on patients, and a fourth analyzes results. The teams do not know each other, and are prohibited from personal contact of any sort, on peril of contaminating the results. This man had been sitting in the Frankfurt airport, innocently chatting with another man, when they discovered to their mutual horror they are on two different teams studying the same drug. They were required to report their encounter to the FDA. And my companion was now waiting to see if the FDA would declare their multi-year, multi-million dollar study invalid because of this chance contact.
For a person with a medical background, accustomed to this degree of rigor in research, the protocols of climate science appear considerably more relaxed. In climate science, it's permissible for raw data to be "touched," or modified, by many hands. Gaps in temperature and proxy records are filled in. Suspect values are deleted because a scientist deems them erroneous. A researcher may elect to use parts of existing records, ignoring other parts. But the fact that the data has been modified in so many ways inevitably raises the question of whether the results of a given study are wholly or partially caused by the modifications themselves.