The chemical basis of mutations is quite well understood. There are framshift mutations, which arise from an addition or deletion of a base - intercalating agents often bring this about - , and substitution mutations, which generally arise from modification of a base so that G, for example, looks like A during the proces of replication. Among the mechanisms are alkylation (attachment of an alkyl group to the base), nitrosation (substitution of an amino by a hydroxy as a result of reaction with nitrosonium ion), and several others I've forgotten.
This seems an incredible statement from an evolutionist whose entire existence is grounded in the inductive.
Your crystal ball needs polishing. I simply point out the logical consequences of that sort of thinking. To my mind, sniping at the inductive principle falls into the "yeah, but whaddaya gonna do about it?" category - no, it hasn't been proven valid, but it has empirically demonstrated its own worth. Inductively speaking, the inductive principle is valuable, worthwhile, and useful. If that strikes you as circular, congratulations, but you're not the first to notice.
Personally, I find it rather amusing that a pair of avowed believers are seizing upon the arguments of that ultra-rationalist, über-skeptic, and militant atheist, David Hume, in order to defend against a perceived attack on the very thing that Hume himself spent so much effort denying. What can I say, other than that making one's faith contingent upon material propositions may be unwise? If you see me pointing that out as necessarily being an attack upon the Divine, all I can tell you is that nobody is forcing you to make a stand on that particular hill. Sooner or later, faith and reason will come into conflict when you set them against each other like that, and if it's not me, it'll be someone else who pulls the plug that is currently keeping an untenable worldview on life-support. Maybe you'll see that on your own - you're both quite clever enough to arrive at that conclusion without anyone pushing you there.
If general_re can find a picture that seems to be designed but is not, then nothing is designed?
You overload the game beyond its intent, a conclusion which I explicitly deny above. I understand what you're worried about, but all I can do is suggest again that you not hitch your spiritual wagon to material propositions like the design inference.
If it turns out that the design inference leads to a declaration of design where none exists, then the game is over and we may immediately discard the design inference - we are assured that the design inference never produces false positives, and so if it does, it will have failed by its own standards. Beyond that, if the design inference is demonstrably able or unable to reliably tell us something we don't already know, we may infer from that the usefulness of the design inference. As for the consequences of success or failure, I am content to let the chips fall where they may. I think it will fail, but we will see. If the potential failure concerns you, perhaps you ought to offer some advice to Diamond about how best to apply it, rather than trying to cut your losses before the game even ends...