Precedent

Lately, I’ve been noticing more and more appeals to precedent in arguments. Note, I’m not innocent of this myself.

The idea that precedent is definitive is, in my opinion, highly flawed. Precedent (assuming that it is, in fact, precedent and not something unrelated to the issue in question) is certainly relevant to a discussion or debate, but it should not be considered authoritative.

Precedent is what someone else, in an earlier time, in a similar but not identical situation (since no two situations can ever be TRULY identical), did. It does not mean, please note, that what they did was right or had a good outcome even then. If someone decided to round up six million Jews and kill them there’s a precedent for that. It would be a very, very bad precedent to follow.

Precedent is, however, worth noting. If you can extrapolate your future position from your current position without being informed by one or more precedents you are quite lucky. Most actions have unforeseen consequences. If you are able to look at the unforeseen consequences of similar actions to those you are contemplating in the past, then those particular unforeseen consequences won’t be unforeseen. They may still happen, of course, but at least you can try to prepare for them.

Precedent seems to be especially prevalent in the modern US judicial system, taking precedent (gotta love the English language) even over the written law. This often angers me. If nothing else, it should be noted that judicial precedents are often overturned. Surely something that is repeatedly shown to be flawed should not be relied upon?

As an engineer, of course, I use precedent every day. We call it ‘test results’ or something like that, but we operate on the basic premise that because something happened once (an object of such-and-such characteristics failed under such-and-such conditions) it can, and at some point probably will, happen again. If we have a lot of matching precedents (ten similar objects that all failed under similar conditions) we predict the future with confidence (another similar object will fail under the same conditions). Without precedent there would BE no engineering. You can’t do calculations without some basis to do them upon.

There is, however, a key difference. Engineering is quantified, and a chaotic element is hammered into the brains of up-and-coming engineers. Any good engineer allows a ‘factor of safety’ based on how good their precedents are and the consequences of failure. When precedents fail to be predictive we study them to learn why. And quantify that data and make it part of the NEW precedent.

Human lives are, at present, not subject to being quantified as individuals. The chaotic factors are too high, the variables too uncertain. Engineers can predict with very high confidence the minimum level of force and the application of it needed to destroy a piece of metal of known type. Not so human beings. Part of that is our variability – note the ‘of known type’ bit. If I don’t know whether I’m hitting aluminum or steel I have no idea how much force to apply. Without knowing the grade of steel and its characteristics (hardening? Temperature?) I likewise don’t know enough. Human beings are not so easily tabulated. Our actions are even less so.

Humans in groups are a little easier – as with any large system, the mistakes tend to cancel each other out. This is a basic principle of system engineering – you need not assume the worst case for all your material properties. Similarly you need not assume that all people are at the bottom end of the bell curve.

Again, though, there are parallels: good engineering insists on recognizing that some of your components WILL be at the bottom of spec (or even below it). We must also recognize that some humans in any large group will be at the bottom of the moral bell curve. They are our criminals.

There are, however, even more important divergences. Again, humans are not easily tabulated. If one is presented ten samples of a steel tempered to ten increasing levels of hardness, provided with data for all but the fifth and asked to predict the properties of the fifth an engineer can do this with high confidence. This is called interpolation, and is possible because one has carefully controlled all but a single variable. Multi-variable systems require many more data points, and have a strong tendency to have points of chaotic behavior. Many bridges had been built similar to the Tacoma Narrows Bridge (famously the ‘Galloping Girdy’). Only that EXACT bridge under those EXACT wind conditions was destroyed by resonance. The same bridge in another place might have lasted a hundred years. Had a dozen similar bridges been erected in the same place both ones of greater and lesser structural integrity would almost certainly have survived. A bridge of equivalent ‘strength’ but different design would have survived. Interpolation based on even very good data could easily have produced a failure like the GG (i.e. building multiple similar bridges in the same area in a range of stiffnesses, size, etc. bounding the intended design). A bridge is a complex system. So are people… except people are much worse.

Worst of all, humans, unlike any other material dealt with by engineers, are self willed. Steel does not WANT to break (or not break). A bridges does not CARE if it stands or falls. Again, I, like most engineers and non-engineers I know, routinely imply that this is not the case. We ascribe motivation to objects when they fail (or don’t fail when we expect them to), or blame it on the gods, take your pick. Humans may be aware they are being measured and their actions predicted and may choose to act on that information. Steel doesn’t know it is about to be cut, and can’t harden itself to resist (or soften itself to be ‘helpful’). Humans may choose to do either one.

And so we get back to my contempt for judicial precedent. Judicial precedent is an attempt to handle an individual by its nature – large groups are rarely involved. A single, original precedent is typically cited, rather than the body of decisions already based on that precedent. Again, note my contempt is not for the law – setting a standard is a necessary stage in gathering data. Worst of all, the huge range of variables present between any two human beings are routinely ignored in favor of a few similarities.

As yet, we cannot even truly deal with human bodies in engineering terms (most medicines, for all their extensive testing, would be considered to have unacceptably high failure rates in most engineering disciplines). Human brains are, from the limited evidence available, much worse.

I say, leave precedent to the engineers. The justice system can have it only after the medical system gets its error rate down.