Near the end of the service, a set of prayers is said, one of which may be omitted (the BCP provides a vertical line next to optional paragraphs). The optional prayer concerns procreation.

I take this to mean that the procreative event is not necessary for a definition of marriage. Many heterosexual couples choose not to have children. Some are incapable. Others, such as those who marry at advanced age may be past child-bearing years.

It seems that the procreative argument turns a blind eye to heterosexual marriages that do not include children. Extending the argument to include these groups shows the fallacious nature of said argument.

(1) Is #2 really an exaggeration fallacy?

For example, consider this situation (biased source alert):

http://www.wnd.com/index.php?fa=PAGE.view&pageId=61342

Assuming accuracy in the reporting, this appears to cast argument #2 in a different light. Rather than an exaggeration, it is a slippery slope argument in this form:

(A) If we allow gays to have marriage rights, and
(B) If marriage rights are given civil protections, then
(C) Traditional views will not be able to claim a First-Amendment exemption, so that
(D) Religious objectors to gay marriage will be penalized (or silenced).

This seems like a plausible inductive argument, no?

(2) The fact that America’s birth rate is below replacement level is a Bad Thing. No relationship to gay marriage of course; just pedantically pointing that out.