Here's a neat debate: where should we peg the minimum wage? Where it was before in Ontario was typically at just above the poverty line threshold (which is based on average cost of living for good etc I believe), which was around $20k a year (for a single person) last time I checked. $15 an hour raises minimum wage to 30k a year.
If you're going to make a minimum wage at all, you can't just pull a random # out of your butt that "sounds good", it should be based on some kind of logical metric.