Do you think that eventually an individual or a small group of people (terrorists, doomsday cultists, etc.) will be able to engineer a very destructive biological weapon using off the shelf synthetic biology tools? Or will synthetic biology never develop to that point, or it's likely that synthetic biology or other technologies will give us defenses against such weapons before they become possible, or do you see effective regulation happening first, or something else?
For a given value of off-the-shelf, I think that's doable now. Not x-risk destructive, but millions dead. I haven't looked too closely at it in the hopes of staying off watch-lists. The materials necessary are much easier to obtain than those necessary for other sorts of weapon, so I'm guessing our only defense right now is the high level of education required to do it. Regulating this will be like trying to keep people from using 3D-printers to make weapons: your only real option is to forbid all the printers. And you couldn't just forbid "synthetic biology". You would basically have to take all molecular biology off the table to prevent people from being able to build diseases.
The FHI's mini advent calendar: counting down through the big five existential risks. The second one is a new, exciting risk: synthetic biology.
Synthetic biology
Current understanding: medium-low
Most worrying aspect: hackers experimenting with our basic biology
Synthetic biology covers many inter-related fields, all concerned with the construction and control of new biological systems. This area has already attracted the attention of bio-hackers, experimenting with DNA and other biological systems to perform novel tasks – and gaining kudos for exotic accomplishments. The biosphere is filled with many organisms accomplishing specific tasks; combining these and controlling them could allow the construction of extremely deadly bioweapons, targeted very narrowly (at all those possessing a certain gene, for instance). Virulent virus with long incubation periods could be constructed, or common human bacteria could be hacked to perform a variety of roles in the body. And humans are not the only potential targets: whole swaths of the ecosystem could be taken down, either to gain commercial or economic advantages, for terrorist purposes, or simply by accident.
Moreover, the medical miracles promised by synthetic biology are not easily separated from the danger: the targeted control needed to, for instance, kill cancer cells, could also be used to target brain cells or the immune system. This would not be so frightening if the field implemented safety measures commensurate with the risks; but synthetic biology has been extremely lax in its precautions and culturally resistant to regulations.