We're getting disconnected
I don't believe we need conclusive scientific evidence that over-use of these devices and a tendency to replace traditional means of social interaction with social networking tools disconnects us from society and may also retard or harm our overall developmental skills, particularly if we are exposed to them at an early age.
Those of us who already have difficulties in social situations or have Autism Spectrum Disorders and associated co-morbid conditions such as ADHD and ADD should be making an extra effort to get out and be with people, and not become recluses with our tech toys.
The signs are certainly out there. You only need to walk into a restaurant to see supposedly mature adults at tables mindlessly texting or "liking" and sharing rather than engaging in focused conversation with each other.
You only need to go to a public park and watch people stare at their tablets or phones rather than take in a beautiful summer's day watching the marvels of nature or to people watch. Or ignoring priceless works of art displayed at a museum, instead fixated on their business calendars and corporate emails when they are on vacation.
You only need to observe your own children at family gatherings who would rather be texting peers of their own age -- frequently in the same room with each other -- than having to communicate verbally with anyone.
Is this the society we want for ourselves? For our children? Or are we doomed to transform our great civilization into a sea of stupid?
We're making the right connections
Looking back over my esteemed opponent's argument, the same issue keeps coming out. The message he's giving is that there is something inherently "anti-social" or "unsocial" about how connections are made on these devices.
This is a point that I completely disagree with. Over time we will see a normalization whereby real life and digital relationships converge and become indistinguishable, and I don't see this as a bad thing. It creates more ways in which we can interact, share ideas, and communicate, not fewer. Why should baking cakes with granny in her kitchen in real-life be more worthy than spending an hour talking to her over Skype on a bus ride home.
This debate was inspired by an article written by my esteemed opponent in which he describes an art gallery visit where he was looking a smartphone rather than looking around at the works of art that surrounded him. He lamented the distraction -- to me, that should have been something to be celebrated. He got to enjoy the artworks, and alleviate stressors related to needing to answer work emails, and spend time with his wife. It seems to me that in that moment he found a win-win, not a win-lose.