Security of Unix & Linux systems. If your question is about balancing the pros and cons of a security policy, you may be interested in the IT Security site.
Computer security deals with ensuring three properties:
confidentiality, i.e. data is not leaked
integrity, i.e. data is not corrupt, data is received as it has been sent in the correct destination
availability, i.e. a given service is available under all circumstances, for example, it's resilient to Denial of Service attack
For some systems, for example in cars or airplanes, another insteresting property is the safety. This is the warranty that the system will not put human life at risk while running or because it does not function properly.