Read this excellent post by Jay Reding.
"At any given moment, any given employer can only spend so much for wages. That figure may vary over time, but a “living wage” means that employer has to make do with the same amount of money, but much higher costs. That means fewer jobs, and that means that employers are going to want to take as few risks as possible with the people that they do hire.
The “living wage” sounds good in principle, but the reality of the situation is that it would be devastating to the least fortunate among us"