Question

Background information: This is an excerpt from a speech given by William Wilberforce to the British Parliament in 1789.

As soon as ever I had arrived thus far in my investigation of the slave trade, I confess to you sir, so enormous so dreadful, so irremediable [incurable] did its wickedness appear that my own mind was completely made up for the abolition. A trade founded in iniquity [evil], and carried on as this was, must be abolished, let the policy be what it might,–let the consequences be what they would, I from this time determined that I would never rest till I had effected its abolition.

–William Wilberforce, 1789

What primary argument is Wilberforce making for the abolition of the slave trade in this passage?

The slave trade is no longer necessary.
The slave trade is an enormous part of the economy.
The slave trade profits Great Britain.
The slave trade is evil.

Answer 1

The slave trade is evil.

Wilberforce calls it "so enormous... so dreadful" and "founded in iniquity" and says its "wickedness" makes abolition imperative, so his primary argument is moral — the trade is wrong and must end.