Wow, someone downvoted that. Could you elaborate on why you think reducing social cost is a valid argument for promoting suicide? Note that I'm not saying there aren't valid arguments supporting the St Paul's approach, I'm only suggesting that "because it's cheaper" is an incredibly callous and cynical one.
I didn't downvote you, but to answer your question, first, no one is promoting suicide. This system allows people to lead a life you don't consider worthwhile, but they are still living, and the life they are living seems to be objectively better than the one they would be living otherwise. In addition, it's cheaper. So win-win.
If it wasn't cheaper, their would still be an argument to be made in favor of wethouses because it seems to be far more humane than allowing people to rot away on the streets. But then the debate would be whether or not society should have to bear the cost of their poor decisions. In fact, they will have a cost to society no matter what. It just so happens that the best thing for them is also the cheapest thing for society, so there is no possible objection. So the argument goes.
No one is saying, "Do it because it's cheaper." They're saying, "Don't not do it because it's more expensive, because it isn't -- it's cheaper."
The tag line of the article reads "It's a place where the most hopeless of alcoholics can drink away their final days at less risk and cost to the public." That sounds like a place where they are invited to come and commit suicide, albeit slowly. I certainly agree that the alternative of turning them out on the streets is less humane. But what about the alternative of committing them to an institution where they have a chance of being cured of their addiction? What about the alternative of a life where they're sober?
The article implies that all of these men are incorrigible, but many might simply be people with families who don't have the resources to get treatment, or that simply don't care enough to get it. There is a great danger that because it's cheaper, we'll rationalize away the moral argument in much the same way you do, by pretending that there is no alternative but putting them on the street.
