We can imagine a lot of things, some clearly impossible, some plausible.
Are you tripping too hard over "imagine?" Should I have just said "think of?" You tell me you don't see how the Old Man of the Mountain could have formed or been destroyed without design. I can think of ways in which both could have happened without design.
But let's stay with "imagine." You say something can't happen without guidance. I imagine otherwise. I give you a scenario which is all physics and chemistry, no intelligent being stirring the pot. If it's on one of these threads, your next line is "What's the PROOF of that?"
ID-ers could just skip the whole first step, the attempted proof by failure to imagine, but then I guess guys like Behe would be out of business.