What is contextual argument?

It is an argument derived from the context of the topic.

For example two persons, a man and a woman are talking:

Man: That lady over there is very beautiful

Woman: I agree, although I do not think her shirt suits her eyecolor

This is an contextual argument, it is related to the subject

Non-contextual argument would be:

- The weather this summer has been awful

- Pink teddy bears are tacky

see, completely out of context