Why is the number '12' so prevalent in lists of ideas/principles?

Consider the following, as examples:

• 12 Principles of Animation

• The 12-Factor App

• The Twelve-Step Program

I find this curious. Why not - say, 3 or 7 or 20, or 100, for such sets?

I'm Actually Pro-7

Instinctively, I prefer the number '7' as an 'innate' grouping counter.

I would urge you to consider:

1. '7' is an indivisible prime number. That gives it a certain je ne sais quoi - a feeling of 'perfection', of cosmic order.

2. The number '7' has significant symbolism (religious, historical, mathematical) across domains:

   • The seven wonders of the ancient world
   • The seven heavens
   • The seven days of the week
   • The seven deadly sins
   • The seven sages
   • The seven notes of the diatonic scale
   • The seven classical planets (Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn)

3. '7' ties closely to a key human limit: i.e. we humans can typically only hold 7 ± 2 items in short-term memory (as per Miller's law).

4. There's a minimalist feel to the number '7'. It's not 'as decimal' as 10, not as primal as 3 (think of subitizing), and not as boundary-pushing as 12.

5. As a lawyer, the number '7' feels like just asymmetry:

   • In courtrooms, having an even number of judges - say 2, 4 or 8 - can lead to deadlocks in close decisions.

   • Thus judicial panels (a coram) are often composed of an odd number of judges. This ensures that a clear majority (e.g. 4-3) can emerge, especially in hard cases.

   • Justice, therefore, rests on asymmetrical corams: panels of 3, 5, 7, and 9 judges.

   Therefore I love the symbolic weight of '7' - it feels... righteous.

But '12' Does Make Sense...

1. It's still a cognitive chunking sweet spot. The number 12 feels 'comprehensive' without being overwhelming; 7 might be too limiting. And anything more than twelve? That might be too much to swallow for beginners (who need guidelines of digestible length).

2. Canonical cultural/historical usage and legitimacy. Consider:

   • 12 months in a year
   • 12 hours on a clock face
   • 12 zodiac signs
   • 12 disciples, 12 tribes of Israel, 12 Olympians, etc.

   (And we're not even counting trend mimicry, when '12' became a sort of template/meme for frameworks.)

3. Modularity in grouping/categorization. I personally find this to be the strongest argument in favour of the number '12':

   • 12 is divisible by 2, 3, 4, and 6.

   • Counts of 12 can break up ideas into items of 3x4, 4x3, 2x6, etc.

   • Thus divisions of 12 scales neatly with layouts, tables and diagrams (i.e. for segmenting cells, rows/columns and grids). Which makes it fantastic for documentation and pedagogy/information work.

Even though people might never consciously stop to consider why, I think that last reason is perhaps why the number '12' stands out as a structuring element for making sets of principles.