From the dangers of writing by numbers to the dangers of thinking by them. No, not statistics. I like a good stat as much as the next person. Possibly more so, given that many of the next people are medieval historians. I'm talking instead about a certain sort of textbook, usually in the field of business.
They provide diagrams, step by step processes for success in whatever field they devote themselves to, and a general feeling that, just by following their instructions, you too will be an expert at Selling, or Negotiation, or Human Resource Rightsizing (Something with a capital letter, anyway). I've recently been reading something on Creativity, on the basis that being creative... sorry, Creative, is a useful sort of thing when you're writing. The trouble is, I'm not sure I actually learnt that much.
The processes involved were mostly very simple, and frankly didn't deserve a full chapter each. The writing was very positive and encouraging, but the message of it seemed at odds with what they were purporting to teach. 'Follow the same simple methods as everyone else' doesn't strike me as a path to the new or even the interesting. Worse, to 'prove' the validity of these methods, the author (like practically all authors in the genre) resorted to anecdotes. Entertaining, but not exactly evidence.
My chief objection to this sort of thing lies in the relationship between technique in something, general attributes such as intelligence, and actual ability in the chosen activity. Too often, the goal of this sort of thing is stated as 'excellence' (which makes me come over all Bill and Ted for a moment) when in fact the likely outcome is dragging people up to a very basic level. On the basis of what is sometimes no more than a vague thought, people are learning rigid approaches to life, business, and worst, their own thinking processes. Thinking ought to demand more than just going through a series of flowcharts.
They claim to be following the processes used by the best people in particular fields, but one thing I've noticed from my own (equally anecdotal, so look for yourselves) observations on people who are quite good at what they do is that 'method' is a secondary concern. The way you find some of the real experts at something is to look for the ones who are doing things rather less by numbers, not the ones who are stood there trying to remember what the book said they should be doing next rather than giving the activity they are engaged with their full attention.