William of Occam. His should be a household name. Philosopher and theologian, William was born around 1285 in the town of Ockham, not far from London.
William adhered to the principle of "plurality should not be assumed without necessity" (although he adhered to it in Latin, which, after much wrenching soul-searching [and heavy drinking], I decided not to burden you with). In other words: don't worry about more than you need to. This has come to be known as "Occam's Razor", since it seeks to "shave off" unnecessary items. He didn't formulate the principle himself, but was famous in his day for applying it. [Sadly, to the best of my knowledge, none of William's online help files survive.]
What all this means, in English, is that, when there are multiple theories to choose from, the simplest one that still fits all the facts is the one to go with. The part in italics is what most people conveniently overlook. Occam's Razor doesn't tell you to just go with the simplest explanation; it says that the simplest one that still accounts for all the data is the one to put your money on. Kinda like "Keep It Simple, Stupid", isn't it? William is telling us not to throw in more than we need in order to come up with an answer.
And how does this relate to Technical Writing? I thought you'd never ask!
How many times have you decided to add "just one more paragraph" or "just one more example" to one of your manuals? Wait! Wait! Before you raise up your hand to smite me, that's not a bad idea. Well... maybe it is and maybe it isn't. (Boy, if I'm not good at weaseling, who is?)
The point revolves around whether the additional material accomplishes anything. Have you simply restated what you've just written or are you actually saying something new?
If you're restating, why are you restating? Is it because you think it will make things clearer? If so, doesn't that imply a nagging suspicion that what you just wrote doesn't cut it? If you're already afraid that your explanation isn't clear enough, wouldn't it be better to rewrite it rather than throw in additional text to "simplify" things? In truth, you may have just muddied things up a bit.
Except for minor changes, is your second example exactly the same as your first? If so, why bother with it? If the first example isn't simple enough to be understood, chances are that the second won't be either. If the first example is crystal clear, what's the function of the second? Is it reinforcing or just redundant? (You, of course, feel that it's reinforcing; however, what would the PBC ["Poor Bewildered Customer"] think?)
If you're saying something new, does it build on what you said before or are you heading off in another direction? Neither is wrong per se. What's important is that the PBC knows where you're off to. Have you simplified the customer's life by providing useful explanations and examples, or do you just feel that your manual is more worthwhile because it's longer? (Put that brick down!!! I'm not accusing you of padding your manuals. [Wow! I think they actually bought that!] Just ask yourself if you honestly feel that "longer manuals are better manuals".)
Does any of this relate to Occam's Razor? Of course it does!
You may not realize it, but when you write instructional manuals you're starting with premises and working towards a series of conclusions. That's the basis behind telling the user why something should be done, how to do it, and the result of having done it. It may not be as esoteric as how many angels can dance on the cover of a PDF [418, assuming you put the band somewhere else and pay off the fire inspectors], but the theory holds. Therefore, you should consider shaving off whatever isn't needed so that the PBC reaches the correct conclusion without having to worry about more than is necessary.
So, ask yourself this: if your manual were edited by William with his razor (or, for that matter, by Freddy Krueger with his knives or Leatherface with his chainsaw), would it survive the onslaught? Remember, "less is more" (a phrase that goes back to Robert Browning's 1855 poem, Andrea del Sarto). Just keep in mind that the PBC has enough to contend with without a manual chock full of redundancies.