Should it be $5,000 per month so that the full costs of an apartment in NYC/SF so that a family could on with their lives undisturbed by unemployment? Or, should it be $500 to cover just the most fundamental needs of shelter and nourishment in the Midwest?
There are many levels in-between -- it's just as impossible to decide between $1,000 and $1,500 -- and if you went ahead to implement UBI, the conflict this would cause would halt implementation.