Open Source and Security

Its often said by those not in the know, that open source software isn't secure. Its often difficult for me to explain why. Simply saying because everyone can see the code doesn't make a lot of sense - surely that means its less secure? 

Well... Imagine you are a president of a country, or organisation, that isn't in favour with the rest of the world - would you trust software where you couldn't see what the source code was doing?

Here is an excellent article about Richard Stallman who was saying the same thing 30 years ago.