Unemployment isn't UBI. If you work you lose the unemployment money you would have got for free, hence the disincentive. UBI (most proposals) would supplement work not replace it.
With UBI, if you take an additional job, you would lose a large share of your income to taxes used to pay for the UBI.
Yes, you can restructure income tax levels so that people get to keep most of their additional income, and then you'd have to tax the remaining people more heavily to compensate. But if that's the solution, why don't we do that today?
This argument shows that UBI doesn't solve the incentive problem. It can only be solved by keeping welfare benefits significantly lower than minimum wages, which means lowering one or raising the other. This isn't logically impossible, but it's matter of political feasibility. That's true of UBI also.
I don't necessarily disagree. I think UBI is an important thing to study and consider as we increasingly displace workers with the ever-moving capability of tech, but it will undoubtedly have some unintended consequences.
I do think it's important to point out though that you lose unemployment if you work, so there's direct incentive there.
The U means that you still get your monthly basic income even if you work. With unemployment working earns you 10-20% more. With UBI working earns you 105-115% more.
The point from most of the comments seems to be, if unemployment is enough to live on and the alternative is a job you don't particularly want to do, then there's no incentive to do the job you don't want to do?
If UBI just replaces unemployment, how does that calculation change? You still have enough money to live on you still don't want to do the job being offered?
Unless UBI is sufficiently low that you need a job to survive, in which case... is it UBI?
Nothing says people aren't willing to work if they pay is good enough. Unemployment is effectively a 90% tax rate in the bottom bracket, making work pointless.
Just look at the Nordic countries, very good unemployment benefits but we do not have any issues with people staying on benefits even if they could get a good paying job.
A UBI that works as e.g. a negative income tax would definitely work.