You mean as a matter of regular inflation? Presumably the base should periodically increase to account for that. I think that's how most welfare programs work.
Yes, in terms of both inflation and Purchasing power of goods.
If everyone is assumed to earn 1000 USD a month onwards, the purchasing power of 1000 USD would drop (even excluding base inflation).
Let's say I'm a business selling groceries, I may be tempted to raise prices of goods as I can assume people have a higher level of disposable income to buy. This is specially true for low-value commodity goods. Nowadays the lowest expected baseline is zero and the average is the medium salary.
Inflation-wise, this decrease in PPI has been happening already for decades (just compare the purchasing power of 1000USD in 1960 vs now).
I just think it would compound to the issue at a faster rate. I also agree there are mitigation measures that could be enacted to control rapid inflation, price & rent controls, and more. But those measures might not be universally well received by people and business alike (generating other unintended effects).
There's a wide variety of proposals out there based on different goals and principles. I think a reasonable policy would vary by region based on actual living costs. $1,000/month is enough to live well in Alabama. In California, there are homeless people living on the same amount.
Indeed, we could set a reasonable amount. If we consider 1000 USD / month in all states, then one of the incentives is for people that don't want to work to move to places where they can maximize their purchasing power (eg: countryside, away from metropolitan centres). This could actually decreased homelessness in big metropolis and decrease pressure on services & infrastructure. All states would need to agree, and some would be subsidized by the Federal Government if needed (UBI would be handed at a federal level I assume). If so, one of the unintended consequences could be an increased asymmetry between states over time (due to the change of demography and internal economic migration incentives).
It varies by proposal. This is the conventional definition as I understand it:
A basic income is a periodic cash payment unconditionally delivered to all on an individual basis, without means-test or work requirement.
Ok, this one can be tricky and I think implementation details would be critical for UBI to work.
For example, if truly unconditional per person and in absence of other welfare programs, then we create a strong incentive to have kids and maximize income per household (not necessarily provide and educate them in the best way). Assuming the best higher education remains private an unaffordable for many, a new generation could grow up with lower skills for the job market, increasing the chances they would rely on UBI and keep unemployed (another compound effect that could strain the system, as more people would draw funds). This would be great for the birth rate though and to be fair aligns quite well with the polarizing future of the job market with increased automation (very high number of non-repetitive low skills & low number of creative specialized ones).
Another issue would be foreign market distortions (assuming a single country implements it)
One could just receive their UBI, fly to Vietnam or a low-cost country and live quite well. If a sufficient number of people opt to do so, this amount to a lot of capital leaving the U.S. economy to foreign countries with no UBI policy (or one with lower thresholds). Again, I concede that this could be mitigated by travel restrictions for UBIs. Possibly withholding the freedom to travel abroad if unemployed or requiring a certain amount of funds.
Any UBI policy would need to be very comprehensively detailed, in order to be resilient, and would need to consider macro-effects on economics, internal & external emigration & immigration policy, population growth & job market prospects, services planning, business incentives and more.
Trust that the UBI policy would not fail would be the last and critical element of the whole endeavour.
If we get a politician who manages to a least try it in my lifetime, I'll eat my hat and give him a satoshi for good measure