Slavery is wrong because it violates the principles of the Declaration of Independence, which include equality, the right to life, liberty, and consent to be goverened.
First slavery violates the principles of equality by treating man like a beast. The acts against slaves made it seem as if they were worthless, which is not equality at all. In the declaration of Independence it states that "all men are created equal." The slaves were men and yet they did not recieve that equality they right fully deserved.
Another reason why slavery is wrong is that it violates the right to life. Slavery keeps the slave from the right to decide weather they live or die. The slave's lives were in the hands of their masters.
The right to liberty is another right being violated by slavery. Slavery takes away a person's right to make his/her own decisions.
Slavery keeps people bound and from ever becoming free. Even when they are said to be legally free, they are never free, fearing that some white man will try and claim them as their own.
Consent to be goverened is a right man also holds. This means that no one can have rule over you without your permission. Slavery abuses this concept. None of these men ever chose to be slaves. They were not asked weather or not they wanted someone to have total control over their lives and so as they pleased with it. Because of slavery families were torn apart.
So in conclusion, as Equiano said, "When you make men slaves you deprive them of half their virtues, you set them in your own conduct an example of fraud, rapine, and cruelty, and compel them, tho live with you in a state of war...."