We are not inferring design to account for a black box, but to account for an open box.

The question is: exactly how did life get here? Was it by natural selection and random mutation or was it by something else? Everybody - even Richard Dawkins - sees design in biology. You see this design when you see co-ordinated parts coming together to perform a function - like in a hand. And so it's the appearance of design that everybody's trying to explain. So that if Darwin's theory doesn't explain it we're left with no other explanation than maybe it really was designed. That's essentially the design argument.

Science is not a game in which arbitrary rules are used to decide what explanations are to be permitted.

In order to say that some function is understood, every relevant step in the process must be elucidated.

We can look high or we can look low in books or in journals, but the result is the same. The scientific literature has no answers to the question of the origin of the immune system.

I find the idea of common descent (that all organisms share a common ancestor) fairly convincing, and have no particular reason to doubt it.

The basic structure of proteins is quite simple: they are formed by hooking together in a chain discrete subunits called amino acids.