The 8th Permaculture principle is to "Integrate Rather Than Segregate" (you can find discussion of the first 7 principles here).

To integrate is to create relationships between things. To segregate is to remove relationships. We often segregate things to make them simpler to manage or think about. This is often our default strategy so this principle is required in order to encourage us focus on forming connections in our designs.

This principle can be viewed as encompassing three other principles that Bill Mollison discussed in his Permaculture: A Designers Manual book:

• Relative Location
• Each Element Performs Many Functions
• Each Important Function is Supported by Many Elements

The principle of relative location underlines the importance of positioning elements of the system so the output or effect of one element is beneficially related to other elements in the system. For example, we can position a deciduous tree in front of the south facing wall of a building so that in summer it shades the building (and thereby cools it) but in winter when the leaves fall, it allows sun through (and thereby warms it). When we are designing we can ignore where an element (tree) is placed with respect to other elements (house) in a system (our property). If we do so we will miss opportunities to exploit beneficial relationships between elements and our design will be poorer as a result. So the principle of relative location encourages us not to think of elements in isolation, or segregated from each other, but rather to look for ways we can position the elements in a system so that a beneficial relationship results. Anything you plant in a garden should, for example, be judged by this principle.

The idea that each element should perform many functions is another way to be more integrative in our thinking. This principle is the foundation for functional design where we ask of each element what functions it performs and how we might derive a benefit from the various functions the element performs. This is in contrast to only looking at an element as performing one function. For example, we might view a chicken as having the function of providing eggs and design a system around this function only. If we examine a chicken a bit more we will note that a chicken also produces manure and scratches the ground alot as it forages for food. By taking into account these additional outputs and behaviors we can start to see a role for chickens in our gardens to prepare our beds prior to planting. When we add chickens into our system it can play a more useful role when we integrate all of its outputs and behaviors into our farm design rather than designing for only one of the useful functions it offers. So another way to be more integrative in our thinking is to look for more functions that an element might provide and then to "stack" those functions in our design. The quality of a design is indicated by how many functions each element in our design performs. Functional design is a skill worth cultivating and Permaculture is fairly unique in its preoccupation with, and techniques for, good functional design.

Finally, for each important function we should make sure that it is supported by many elements. When an important function is supported by many elements, the resilience of the system is increased because if one of the elements fails, another one can kick in and take over. An example is water supply to the home. If the power cuts out, do you still have a way to get water? If your water supply depends on a pump and/or pressure tank and that is your only way to get water, then you will probably have to leave your property to get water. If, however, your water is gravity fed, and you are harvesting rainwater, and you have a pond, then you will be ok in the event of a power outage or drought conditions. So another way to foster integrative thinking is to examine important functions that you need satisfied and then look for multiple ways you can support that function within your system rather than just accepting one solution.

Bill Mollison advised that "The core of permaculture is design. Design is a connection between things. It’s not the human, or the chicken or the garden. It is how the human, the chicken and the garden are connected.". Permaculture works well in the garden but it is meant to inspire, and to be applied to, designs outside of the garden.

When you first read "Integrate rather than Segregate" you probably had some immediate commonsense ideas about how to interpret this directive. These commonsense meanings are intended in this directive as well. You can think of the three sub-principles as giving you some less-obvious ways to think about how this integration principle can be applied.

For further discussion of this principle, see Deep Green Permaculture's discussion of Permaculture Design Principles, especially the first three principles.