"Look at the perfection of design, that must suggest a designer"...or some similar argument is made by theists regularly and has become one of their church hymns. Many of them say that if a bomb goes off in a junkyard, that cannot create a fighter jet;Therefore a designer must exist for "creation.".....ummm ot really Mr. Theist.
One must be careful when debating this topic with theists as they have alot of holes they will try to suck you into.
Firstly, explain to Mr. Theist that junkyards, paintings and other man-made implements are not systems (biological or cosmical) hence they cannot assemble themselves. Evolution by natural selection however can produce a specie overtime. Explain to Mr. theist that lower life forms via natural selection, adapt to their surrounding environment hence slowly climbing "mount improbable." We have never seen bits of paper (for a painting) being assembled before our eyes but we have seen DNA being assembled many times even from non-living matter (Miller-Urey experiment as well as the more recent experiment done by the french scientist montonye see here:http://www.larouchepac.com/node/17802 shows chain links of amino acids and the basic components of life being formed through abiogenesis.) Furthermore, going by your own logic, who designed the designer? It is completely irrational to state that the designer is..."just there", as it blows a hole in your entire story.
A design does not mean there was a designer, as biological systems evolve via natural selection all on their own, this is fact.