All this comes down to finding objective criteria for design, and no one has - at least there's no consensus. I might be able to come up with some, but you wouldn't like them. As I suggested previously, in intelligent design, form follows function - but in fact, in nature, form very often follows phyogeny, not function. Intelligent design is parsimonious, efficient, and rational - but nature often 'solves' problems several different ways, and makes irrational choices between alternatives, at least viewed from the standpoint of function. Why design a penguin flipper like a bird wing; and not design a bird wing like a bat wing, or a penguin flipper like a whale flipper or a fish fin?
The closer you look at nature, the less designed it looks.
We won't hold our breath waiting for consensus, will we?
but nature often 'solves' problems several different ways, and makes irrational choices between alternatives, at least viewed from the standpoint of function.
We should not expect any rational choices from random chance even when "guided" by laws or principles. Although by "irrational" you meant "irrational to us," even that judgment is difficult to make with such a paltry evolutionary contrivance that yields a nearly endless variety of phylogenetic trees.