The final aspect of intelligent design is that of systems within systems. The previous discussion and example of the bacterial flagellum involves an extremely simple system with as few parts as possible. It is used to present the truth that systems cannot be built one part at a time. Of course it must be remembered that each of these parts are actually chemical parts and quite complex in themselves. However, living systems are far more complex than this. The cell is the basic unit of life. Cells are organized into tissues and tissues are organized into organs. Organs are organized into organ systems and these are organized into organisms.
We have many of these organ systems such as the nervous system, the immune system, the digestive system and the cardiovascular system. All of these systems must be together at the same time to function and to have life. Each system is interdependent on the other systems. The neurologic system cannot function unless the digestive system works to isolate nutrients and then these nutrients must be delivered to the neurologic system through the cardiovascular system. If any one of these systems does not work, or had not yet ‘evolved’ the organism could not be alive. It is the same logic as how the parts of any one individual system must be together for the system to work. Here each of many systems of cells, tissues, organs and organ systems has to be together for there to be life.
All organisms have interrelated organ systems and each of these organ systems has interrelated organs and each organ has interrelated tissues and each tissue has interrelated cells. There are systems within systems within systems within systems. There are layers and layers of complexity in life. Each layer is complex by itself and each one dependent on others to have purpose and to be alive.
If cells within tissues within organs within organ systems within life cannot be developed one step at a time with each step the result of a random chance mistake and where each step creates a structure that is both useful and better to give a survival advantage, then evolution logically cannot be possible.
These are the many aspects of intelligent design. Biologic systems have irreducibly complex parts, there must be assembly instructions for previously nonexistent parts, the individual parts and their assembly instructions must be the result of DNA mutations, and there are an endless number of systems within systems within systems.
Each and every one of these aspects of intelligent design must be explained by evolutionists for evolution to be true. Currently there is no evolutionary explanation for any of these aspects of intelligent design. Intellectually and logically, the inability to explain even one of these issues is enough to make evolution not possible. For instance, even if you believe that irreducibly complex parts exist from undirected processes and even if you believe that systems within systems can develop one part at a time even though each part has no usefulness until all the parts are present, evolution is still impossible, even if the only part of this that is true is that there is no way to have assembly instructions in the DNA for nonexistent parts. On top of all of that, all of these together are only one of the 50 controversies that all need to be true for evolution to be true.