Two-man, Four-eyes Principle

4 eyes rule

WHAT is the Four-eyes Principle?

The four-eyes principle is a working rule that any work must at least go through two individuals for some form of actions before it is deployed. In a business context, the four eyes required for approval are often those of the CEO (Chief Executive Officer) and the CFO (Chief Financial Officer), who must both sign off on any significant business decision. In editing, proofreading and translation, documents typically have a second reader to detect errors and typos that a single pair of eyes might miss. Although neither individual might detect all errors, two readers are likely to miss different things so that, collaboratively, they will catch more mistakes. In software development, four-eyes mean that software code could co-developed by two person using the pair programming model or reviewed by a reviewer using the code review model before the testing phase.

WHY do we have it?

Because four eyes see more than two. When done well, the four eyes principle helps to get information from the eagles view. It can help to find weaknesses in architecture, design or code and can help to improve the quality with the well-known four eyes principle. It protects against negligence and adds an element of security to any decision-making process. Most importantly, four-eyes protect the development principle here at Titansoft — To uphold stable quality and fast delivery of our software products.

HOW do we do it?

PAIR PROGRAMMING — An agile software development technique in which two programmers work together at one workstation. One writes code while the other reviews the code as it is being written. While reviewing, the observer also considers the “strategic” direction of the work, coming up with ideas for improvements and likely future problems to address. This frees the driver to focus all of his or her attention on the “tactical” aspects of completing the current task, using the observer as a safety net and guide. This is normally adopted for sensitive actions, such as critical database changes in the production environment.


Code review is a systematic examination (often known as peer review) of computer source code, such as using Enterprise C# or under Visual basic Studio 2013/ .NET environment. It is utilised to find and fix mistakes overlooked in the initial development phase, improving both the overall quality of software and the developers’ skills. Code reviews help to get information from the eagles view. It can help to find weaknesses in architecture, design or code and can help to improve the quality with the four-eyes principle. This is usually adopted for regular planned items where implementation actions happen in a sequential order, allowing a standardised workflow to form within the implementation team.

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