A double standard is when two things should be treated the same, but they are treated differently. This is wrong. Most people don't realize that the reverse is true. It is wrong, when two things should be treated differently, but they are treated the same. I suppose you could call this "a single standard", as opposed to a double standard.
Here are some examples of when it's wrong to treat different things equally:
- The government treats me and Bill Gates as the same, in terms of how much money we owe in taxes.
- I am treated the same way as a criminal, because I am the same gender/race/religion as many criminals
- I am given just as much right to kiss the President's wife as the President does
Anyway, here's the point I'm trying to make: things that are the same should be treated the same, and things that are different should be treated differently. That's a general principle I work off of. As you can see, it's slightly different from the principle of "treat everything the same, no matter what".