Common Design or Dissimilar Design?
So what is the point of a common design? The point is, based on direct observations and experiences, that a common design leads to a number of similarities. And all living organisms show similarity at the genetic level. All nucleotides are the same. All amino acids are the same. Protein manufacturing is also the same.
That said a common design explains the similarities and the differences are explained by the different applications and differing functional requirements. For example- All houses built to the same building code(s) will have that degree of similarity and the differences are explained by the customer's wants/ requirements (or even budget constraints).
Also a common design is one that uses the same standards to construct something. That is the same standards others used to construct something else.
Other examples would be plug-n-play electronics, PC clones, rail-road tracks, roads, bridges, etc. (Russia used a different standard for their rail road tracks forcing Germany to refit their rail road cars to ride on Russia's tracks- WWII)
How does this relate to Intelligent Design? Living organisms were designed to the same or very similar standard. It does not require only one designer. Just one set of design standards that must be followed.
So why, if there is a common design, is there such a wide variety of organisms? Again system requirements. The Earth being the system and it requires a variety ofg organisms to keep it habitable.
Designers can and do take parts that work for one thing and use them for something totally unrelated. For example we use tires on cars and also we use tires on carnival rides, baseball and football throwing machines. That is also a common design- using common parts for different applications.
So far from being a dissimilar design living organisms obviously have a common design.
Cladistics is a method of catergorizing organisms based on shared characteristics. Each clade allegedly consists of a common ancestor and all of its descendents. However we can also say that each clade consists of a common design and all its descendents. All cars are descended from the originally created cars- descended by design. All computers are descended, by design, from the originally created computers. The closer the ancestry the more similarities.
And so it would go for living organisms.