You may be able to change part of their mind and get them closer to what you want, but there is just as much risk that you won't change their mind at all.
In the raise example, you could have a boss who is notorious for not giving raises; therefore your goal of getting a raise could be unrealistic.
One saying goes, "You can't know where you are going, until you know where you have been." With persuasive arguments, it is the other way around.
Instead of knowing where we have been, we are looking at where we are going.
If there is no disagreement in a persuasive essay, then there usually is no reason to write the argument.
However, if you are writing to get a raise, causing an argument is the absolute wrong thing to do.
If you are effective in your persuasion to get the raise that you want, then your goal will be met. The last point that you should remember about your goals is that you need to make your goals realistic.
Typically you only have a few minutes of someone's attention to change their mind about an issue, idea, or product.
We have an end conclusion in sight and we have a goal for that conclusion.
By knowing our goal, we can begin to formulate the entire persuasive argument around that end goal.