I suppose I should clarify what I mean by productive.
I'm using it in it's lowest sense: paying back into society to fund all the other stuff that government will want money for.
So, basically, we will have more takers than producers, therefore, it cannot possibly work.
Sure, you'll get poets, artists and the like taking advantage of it and society will be better off in the long run for it... probably. I don't know, never studied that stuff before.
But the immediate problem is that you will have a shit-ton of leeches that will take the money and play video games all day long. It can't possibly be financially viable.
But to pick up a point from your comment:
> Is (for example) cooking and cleaning and caring for others 'productive'?
I'd wager that it can be for two possible reasons:
1. It perhaps allows the person being cared for to help society in some way (either directly through taxes or poetry etc.)
2. The cleaner gets paid and ultimately puts money back into society.
And yes, there are tons of "non-jobs" where nothing is ultimately created, I get it. But that won't go away with UBI: banks will still have too many employees doing nothing all day (source - worked in banks for years!)
On another note: I live in Scotland and I will bet that within 5 years we will have UBI... we're already bankrupt so, hey, what's another £50Bn a year added to the unpayable debt pile :)