If I'm forced to sit at a communal table in a restaurant or at a large gathering, do I also have to socialize with the strangers seated around me?
While you have no duty to ask after your tablemates' families, health or take on the Canadian economy's crippling productivity gap, you should at least look them in the eye and say hello when you first sit down. You should do this because, if you don't, you'll look tortured and pathetic or, worse, like someone from Toronto – I have seen diners here do everything short of install Plexiglas partitions to prolong the illusion that they're not sitting next to people they don't know.
Besides, communal seating isn't all bad. That renaissance degenerate with the greasy hair and scabid-looking skin who's eyeing your potted salmon from across the table might actually be charming and lovely or even one of the members of Nickelback. You could be sitting with a rock star (or a member of Nickelback). If you don't say hi, you'll never know.