I, of course, made a fuss. I told the barman that I made a point of only drinking beers that were both. I tried to haggle a reduction, failed and got drunk anyway. However, even in my beers, it occurred to me that I didn't really know what authentic meant. Did it mean real, extant? In which case it would hardly need to be pointed out. Did it mean not fake? Who fakes beer?
So, I fled to a dictionary, and of course authentic, etymologically, means something that is by an author, and therefore has authority. So authentic is, or was, roughly a synonym for authoritative and referred to books.
It should be remembered here that in the medieval period there were writers and there were auctors. Auctors were the only ones who had auctorite and whose words were therefore auctentyke, from which we get authentic.
I have to therefore concede that T-shirts could be authentic or knock-off copies. I would also note very, very strongly, that as I am an author The Etymologicon (which comes out in only a few days time now) will definitely be authentic, although it unfortunately contains no beer.
Pre-order it here. Please.
Me in the pub