The Printer Manual Theory
I devised The Printer Manual Theory in the late 1980s/early 1990s.
Many years before Windows became widespread, it was necessary to manually configure many software programs with printer escape codes so it could generate condensed, expanded, underline and other like effects. Some programs like Lotus 1-2-3 and WordPerfect supplied printer drivers but many applications didn't.
So, as an IT professional, I would go to the client's office and ask for the printer manual. Back then these were huge tomes full of technical codes and not just the pamphlets with diagrams to show where to attach the USB cable as they are today. And of course you couldn't download the codes from the Internet.
In response to this request, the client would invariably say, “We don't have one”.
Not: “We looked everywhere and can't find it”;
or, “We threw it away”;
or, “We forgot what we did with it”.
They were always definite: WE DON'T HAVE ONE.
So I discovered that since there was no printer manual sitting in front of them marked, “PRINTER MANUAL THIS IS WHAT THE GUY IS ASKING FOR”, they just assumed it didn't exist, had never existed, and most likely was stolen by space monkeys. Or, more frequently, that it was never supplied in the first place, and probably sold on the black market by the hustler who supplied the printer. And then they looked at me as though I was to blame.
(Years later The Printer Manual Theory could have been replaced by the Office 2000 Theory. Microsoft's Office 2000 required the original CD to install patches, and requests to clients to produce the media always generated the same denials that the CD existed.)
The Printer Manual Theory can be observed in many aspects of life.
The most obvious proponents are politicians when they need to deny something. Politicians can always deny things immediately before any facts are known. Whereas a normal person would say, “I have no idea what you're talking about so I can't comment”, a politican can say “that's completely false” simply because they wish it to be so, or because it didn't occur five minutes ago, in their office, while they were present and with a camera crew filming the whole thing. For a politician, “There's no evidence of that” means, “I looked in all my desk drawers and didn't find anything”.
Another example is the debate about Evolution and Creationism. Creationists seem to base their ideas on the fact that they've never seen a fish changing into a dog so the whole thing must be rubbish. The accumulated store of knowledge about physics, biology, chemistry and geology isn't neatly stacked in their living room so therefore it doesn't exist.