Top Down and Bottom Up

There has been some discussion recently about the top down and bottom up views of rule writing, and the implication of this for the design and functioning of the rules themselves. I suspect (and will attempt to show) that this is a cultural thing, or possibly just another case of the ‘scientific worldview’ invading other areas.

So far as I recall, the bottom up view of rules was the first out of the blocks. Certainly, I remember reading, I think in Charles Grant’s ‘The Wargame’ comments about speed of movement. These were along the lines of a normal person can walk at about four miles an hour on a flat, level, hard path. Thus a unit can move however many inches determined by the ground scale and time scale of the moves. This, again as I recall, is arbitrarily reduced to something reasonable, on the grounds of having to keep in line, the various bits of a unit having to march around blackberry bushes and so on.

So this is a bottom up design of movement rules. We take an individual and assess his capabilities. Then we work out what implications there might be of loading him up with eighty pounds or so of equipment and expecting him to keep in line with his fellows. Even then, we obtain a number which might be a long way from anything with is either reasonable in wargame table move distances, or historically verifiable. Units moved slowly, relative to an individual.

So, of course, Grant (and he was not alone; he is just the author I remember) was well aware of this and fudged the results. In the end, then, it could be argued that despite his explicit bottom up approach to rule writing, he resorted to a top down approach to get the ‘right’ answer.

Such trajectories could be multiplied. For example, there were results of tests around (from, I think ‘Firepower’) of shooting muskets at unit sized sheets, and working out the effectiveness. Despite the author’s charges to the effect that this was an absolute, theoretical maximum, I fear some wargame rules dived in with the idea that muskets were something like 60 – 80% effective, and the body count in wargames rose as a result. Even though the effect of being in battle, being under fire, accidentally shooting out your ramrod and so on were commented upon, rule writers took the headline figure and worked with it.

Now, the people who did these things were not stupid. The thing is that they look as if they are scientific. We all like numbers; they give such an air of authority. A recent incident at work indicated this rather well. A student had done a very nice project and got some clear qualitative data. This was insufficient for her supervisor (who really should have known better) and she was told to do statistical analysis to prove the point. The problem is that statistical analysis on qualitative data is, well, asking to have the numbers made up for you. But numbers have authority where words do not.

Part of the reason for this is, I think, the success of science. Science give numbers; when I was a student you would derive a formula and then ‘plug the numbers in’ to get the required answer. Of course, what everyone knew and tacitly ignored was that the numbers were made up to make the answer pretty. As with so much, even at an undergraduate level, the experiments and problems are fixed so that they ‘work’. That, after all, is how science is supposed to be.

Real life, however, is messy. As an experimental physics researcher, plugging the numbers in became a game a bit like accountancy. If you ask an accountant what the values of a fund is, one of a set of possible answers is ‘what would you like it to be?’ So it is with experimental physics. The question is not ‘what is the answer?’ but more along the lines of ‘how can we get an answer, and how reliable might it be when we have it?’ Numbers, even the outcomes of equations, give us spurious confidence. As someone told me once, ‘it isn’t the answer that is interesting, it is the error’.

So, in wargame terms, we are probably better in going top down, in looking for how a body of men actually performed under battle conditions, be that in movement, shooting or whatever else. This, too, has its dangers, of course. Firstly, the evidence is, to put it politely, patchy. Mostly it does not exist. Where it does exist, we are probably back to those parade ground performance figures which are a guide to a perplexed young officer, but not much use to the old hand sergeant. He knows from experience, and it is not written down in a book.

The problem is, then, that we can neither be purely top down nor purely bottom up. Our records of unit performance are based on individual observations, and may not be valid for all units, let alone all times and space. Top down views are therefore contaminated by, at least, particularity. This unit did this in this battle, so we universalise an individual performance. Of course, bottom up is no better. It takes no account (except through fudge factors, as already noted) of emergent behaviour and bears even less relationship to real life than a top down approach.

But perhaps the major difficulty with the top down approach is the fact that such views of the world are frowned upon, culturally. Science, or at least the perceived method of science, is king. And science is irrefutable (nearly) reductionist, and hence bottom up. The ‘Great Chain of Being’ with everything in its place from worms to slaves to women to men to angels and then God himself has irretrievably broken down (I’m not saying that this is a bad thing), and the legacy of that is that everything now has to be bottom up.

It is just that for writing wargame rules, it doesn’t work very well.