This blog post got me thinking about the reasons I most often hear for using open source software are the freedom it gives users, its usually high quality, and the lack of vendor lock-in.

I have one more reason: transparency.

Most of career to date has been spent as an investment analyst in broking and fund management. I am used information that is reliable because it is subject to independent verification (audit) and those who falsify it are punished. The system is not perfect, but without it there would be far more Enron type cheating, and capital markets would probably not work at all.

Software is also something we need to trust. When we install software on our computers we need to know:

• Is it written to be high quality – i.e. is it secure and reliable?
• Has a malicious author put in a “back door” to steal valuable information – very important for a government or a bank?
• Does it contain spyware or adware?
• Does it restrict what we can do with our own computers?

It is not possible to get a definite answer to these question for proprietary software. This is where open source comes in.

Because the source code (the human readable form of a computer program) is available it is possible to audit it. This means that we can be sure that a program does what it is supposed to do – and no more.

The visibility of the source code also means that it is possible to find independent assessments of the quality of software. A programmer writing proprietary software has every temptation to do a rushed job to meet deadlines and hope that problems will not be apparent till later – possibly years later when they are on another project, or even another job.

With open source bad design will be immediately visible. Again a lesson that I have learnt from the investment industry is that it is much better to give people incentives to do the right thing, rather than relying on everyone doing their honest best.
Most of us will not, of course, go though source code ourselves. The point is that people will, so secrets (such as back doors) will come out.

The incentive to include spyware and similar malicious functionality is also reduced. Open source licenses permit anyone to produce variants of a program. If you produce open source containing spyware, someone will produce a spyware free version of it – and it is not hard to see which users will prefer. So there is no point embedding malicious functionality in otherwise useful software.

Many of us depend on software. We need to be able to rely on it. We need transparency in software.