Such a telling statement. It's my belief that this man does not adequately comprehend the magnitude of the issues at hand. General Hayden, on the other hand, is a man whom I believe to actually understand the technology that he was charged with professional addressing.
He really doesn't understand the actual underlying argument, which is the technical and mathematical fact that a system will either be unreadable by global 3rd parties, or will be readable by global 3rd parties.* It truly is either fully secure from both criminals and government, or it is open for criminals and government to have unchecked free access to our data.
The guy studied chemistry. It's not a "conversation" whether or not particular chemical reactions occur under particular conditions, but fact. Similarly, this is not a "conversation", but fact:
The reality we are faced with is that this easily accessed global communication network carries and connects to basically everything private and public, and all our knowledge of encryption leaves us without a viable "government only" access tool to data.
Any conversation needs to start from the recognition of that technical reality, not before. Comey is tossing this impossible request over the wall to tech companies, completely acknowledging he has no idea how any of that works but that they'll "figure it out", and views that as the way forward.
[* = This is considering that breaches of a mandated government-only back-door to encryption will inevitably happen, be it a leak of keys, attacks on the algorithms, or international information politics weakening the system as a whole. The precedents for these scenarios are plenty.]