In my opinion, the simplest possible argument for UBI, especially if you are arguing with one of those types of people who is head over heels in love with the idea of everyone working hard, goes something like this:

The fact that people need to eat is, obviously, urgent. One must do it 3 times a day and each meal has to be satisfying. It is also urgent that one have a proper place to rest, so as to avoid sickness or body problems from a bad sleeping surface etc.

All of this, it is clear, is very urgent, I think we can all agree. 

Well, as it so happens, when a country like the USA was still developing, do you know what else was very urgent? Work. In the developmental period of USA, it was essentially a joke to find work, thats how easy it was. You walked out of the door and someone was actually begging you to do a job somewhere, on something. Work was, as I say, completely urgent in that period. On every road, in every city, everywhere, there was some type of work being offered. There was so much work that hundreds of thousands of immigrants poured in, for that exact reason. Even when the Great Depression occurred, the problem was eventually remedied because Roosevelt created huge work projects, and the work he created was pretty urgent. Just read this to see why:

The WPA – which in 1939 was renamed the Work Projects Administration – employed mostly unskilled men to carry out public works infrastructure projects. They built more than 4,000 new school buildings, erected 130 new hospitals, laid roughly 9,000 miles of storm drains and sanitary sewer lines, built 29,000 new bridges, constructed 150 new airfields, paved or repaired 280,000 miles of roads and planted 24 million trees.

Well, as it so happens, the conservative argument that everyone ought to work to earn for themselves, makes perfect sense in that environment. Again, work was just as urgent as eating in this version of the country,  so it wasn't really too unfair to put it all in the same pile, and tell a man he had to work, if he wanted to eat. We had a lot to get done, a country literally needed to be built almost from scratch, even in the late 30s. And then, if you go even further back in time, to a year like 1910, try to remember how New YOrk City was in the process, for example, of building subways all the way from 1904 to the 1940s. Thats damn near 40 entire years of an enormous project that we are still enjoying/using DAILY.  Imagine all that work. And don't even get started on the skyscrapers, etc. This type of seriously urgent work was happening everywhere back in the day.

A lot of people, for example, make the argument about the factories going away, and how that was the "grand loss". These people, however, forget all this other work that once was happening, that just  had to do with infrastructure and houses and sewers, etc. There was so much work going on., around every corner.

Now take a look outside your window, whether you're in a small town or a big city. You can almost hear crickets, even in the big city -- thats how little real work is still usally going on these days. Yes there are still construction projects and the like, and many roads do need to be fixed --- but not nearly enough for all Americans DAILY. In our time, the truth is, work is no longer anywhere near as urgent as it once was, when the country was still developing. Everyone now seems to know someone who, even if they are just searching for an unskilled job sweeping floors at Wal-Mart for a night shift, has to send in application after application for WEEKS, sometimes MONTHS, in order to get on the crew. And they might not even get on, and the work might be seasonal, and then they get fired. There is, quite literally, just not that much to do anymore.

Therefore, we see immediately the truth of our time period: Work is no longer urgent. But eating and sleeping well still is. The f act that we have yet to disconnect the two things is not a sign of some sort of honor system,like many think it is. It no longer symbolizes "grit" or anything like that. All it symbolizes at this point is an old system that, indeed, it once made sense, when work was urgent, but now no longer makes any sense at all. Literally at all.