The original observation was in connection with income and wealth. Pareto noticed that 80% of Italy’s wealth was owned by 20% of the population. He then carried out surveys on a variety of other countries and found to his surprise that a similar distribution applied.

The principle has become a common rule of thumb in business; e.g. 80% of your sales come from 20% of your clients.

The principle is also an illustration of a Power law relationship, which occurs often in natural phenomena such as brush-fires and earthquakes. Because it is holds true over a wide range of magnitudes, it produces outcomes completely different traditional prediction schemes. It has been claimed, for example, that it explains the frequent breakdowns of sophisticated financial instruments. This is also likely true of any complex system, including social ones, and increasingly social and community dynamics are seen as falling under this rule in numerous ways, from participation pyramids to abandonment rates.

Occam’s razor states that the explanation of any phenomenon should make as few assumptions as possible. The principle is often expressed in Latin as the lex parsimoniae (law of succinctness):

entia non sunt multiplicanda praeter necessitatem

which translates to:

entities should not be multiplied beyond necessity

This is often paraphrased as “All things being equal, the simplest solution tends to be the best one.” One consequence of this methodology is the idea that the simplest or most obvious explanation of several competing ones is the one that should be preferred until it is proven wrong.

So, how can this apply to web development. There is an analogy between software development and the scientific theory as a means to enhance the credibility of a particular set of programming practices. Once a programmer has a theory (model) of the software in their head, they can talk about and explain its behavior to others. When they make changes to the code, they do so in a way that is consistent with the theory and therefore “fits in” with the existing code base well. A programmer not guided by such a theory is liable to make modifications and extensions to the code that appear to be “tacked on” as an afterthought, and not consistent with the design and philosophy of the existing code base.

Simply, don’t add markup where markup is not needed. Don’t over complicate an application structure. If you have the choice between 2 or 3 paths to the same end – choose one and let it be the simplest and shortest, but with the caveat, don’t cut corners. This will make for cleaner, understandable code with faster download times, something all developers should work towards. CSS has helped this concept immersurably by removing the need to use inline styles, font tags, tables for positioning etc.

In terms of ColdFusion, the use of design patterns (e.g. Singleton, Model-View-Controller…) and the now numerous frameworks (e.g. Fusebox, Model-Glue, Mach-II, Reactor…) has reduced or even removed the concept of “spaghetti code”, the bane of may a web developer’s life and indeed the often muted argument against ColdFusion as an enterprise level application development environment.