3.1.1 What is the Black Box method

A Black Box is any process/device, whose workings are not understood by or accessible to its user. The Black Box Approach to problem solving is a simple but powerful and significant method of dealing with complex problems.
Its main advantage arises from the fact that it makes us differentiate clearly between:
- inputs (or resources we provide)
- outputs (desired goals)

Let's use the general structure of a Black Box, shown in Figure 1:

The Black Box model 

So, we have got an input, a Black Box, and an output.


Inputs (resources) -  this is what we have.


Black Box- this is the place where the most complicated or mysterious things may happen, although we are not interested to know anything about their functioning.


Outputs (desired goals) - this is our result.

Unfortunately, there is one more parameter that we have not mentioned here, yet. This is the environment, on which we will need knowledge, such as:

  • processes needed to transfer the inputs into outputs
  • preconditions for solutions or success
  • external unpredictable phenomena etc.

The environment may have a significant influence on the behaviour of the Black Box.
Of course, we can put the environment into the Black Box too, but in this way we will not be able to make any relevant conclusions about the way the Black Box works.
So, to be able to implement the Black Box methodology, we have to isolate the environment from the Black Box – Figure 2, i.e. we have to be sure that all inputs are linked in a fixed way to the outputs.

The Black Box model, subject to the environment's impact

Unfortunately, this is the most difficult part. In the case of our search engine example, we can predict in no way the number of results and their contents, but we hope that they will be useful for us.