1 Corinthians 15:
Paul's goal in this passage is to prove that R1 is true.
First, he used proof by contradiction to show that there is a resurrection of the dead.
Second, he tried proof by ex concesso:
Ellicott explained:
A weakness of Ellicott's argument here is that Paul knew baptizing on behalf of the dead was wrong but he didn't explicitly condemn it.
Let proposition R1 = There is a resurrection of the dead for all people.12 Now if Christ is proclaimed as raised from the dead, how can some of you say that there is no resurrection of the dead?
Paul's goal in this passage is to prove that R1 is true.
First, he used proof by contradiction to show that there is a resurrection of the dead.
Second, he tried proof by ex concesso:
I.e., it made no sense for those people who baptized on behalf of the dead if there is no resurrection of the dead.29 Otherwise, what do people mean by being baptized on behalf of the dead? If the dead are not raised at all, why are people baptized on their behalf?
Ellicott explained:
The second proof assumed the practice of baptizing on behalf of the dead without approving or asserting it.there existed amongst some of the Christians at Corinth a practice of baptising a living person in the stead of some convert who had died before that sacrament had been administered to him. Such a practice existed amongst the Marcionites in the second century, and still earlier amongst a sect called the Corinthians. The idea evidently was that whatever benefit flowed from baptism might be thus vicariously secured for the deceased Christian. St. Chrysostom gives the following description of it:—“After a catechumen (i.e., one prepared for baptism, but not actually baptised) was dead, they hid a living man under the bed of the deceased; then coming to the bed of the dead man they spake to him, and asked whether he would receive baptism, and he making no answer, the other replied in his stead, and so they baptised the ‘living for the dead.’” Does St. Paul then, by what he here says, sanction the superstitious practice? Certainly not.
A weakness of Ellicott's argument here is that Paul knew baptizing on behalf of the dead was wrong but he didn't explicitly condemn it.