I do not know if the minimum wage ought to go up, or ought to go down. Thankfully, I make a good deal more than the minimum wage so I don't know what it's like to live on it.
However, I am quite certain that a minimum wage is a very good idea. Here's why.
Is the work performed by an employee less valuable, more valuable, or the same value as his wages? If a company is making a profit, then the work performed by the employee is more valuable than the wages paid to the employee. The aggregate difference between the value of the work and the wages paid is equal to the profit of the company.
All companies must make a profit in our system, or they will go out of business. Therefore, with the exception of a few companies that are about to go under, the work performed by an employee is more valuable than what he is paid, and someone else is taking the excess.
Also, consider the value to society of the work performed by an employee. His products and/or services can be sold at a profit because they are valuable to society. I like the new beaf-bean combo burrito at Taco Bell, and I am willing to pay for it. The value to society is equal to what we are willing to pay, which then becomes the wage earner's wages, plus the company profits.
So, consider somebody working at a full time job, but whose wages are so little that he cannot live a decent, acceptable, life, at the minimum standard at which we are willing to accept for our fellow man. Then there are two possibilities. Either, the work he is doing is of so little value to society that it does not equal the minimum that one person consumes from society in order to live decently, or, that work is valuable, but someone else is taking away the profits, and leaving the wage-earner with less than enough to live decently.
What the minimum wage says is that you are not allowed to make a profit off of someone else's labor, unless you are willing to pay that person enough for him to live decently. If you pay him less than enough to live decently there are two possibilities. Either his work is valuable, but you are taking too much of that value for yourself, in which case the law says you must give him a higher share or, his work may not be valuable, in which case the law says you must release him to go seek more valuable employment, and you yourself must also find some other way to earn money, either with a better idea that makes better use of available labor, or by becoming a wage-earner yourself, employed by someone who will take some of the value of your labor.
And I used the phrase "decently" a lot above. What does that mean? It means enough money to live a lifestyle which does not evoke pity in your fellow man. Above all, which does not evoke so much pity that the average citizen feels compelled, through the government which represents him, to provide financial assistance to raise that worker's standard of living to the point that the average citizen considers it "decent". If that happens, i.e. if welfare of some form is given to workers at Taco Bell, we have in effect created a subsidy to Taco Bell.
So, is $5.15 per hour a "decent" wage. (Is that the minimum these days?) If not, it should go up.