That
ruling that teaches the increased liability could not be the
opinion either of Rabbi Ishmael, nor of Rabbi Akiva. It could not belong
to Rabbi Ishmael, because he says that one can be liable only for oaths
that concern the future, not ones that are about the past.
Why could it not be the opinion of Rabbi Akiva? The other part of the
“two that are four” ruling says this: “There are two types of awareness
of impurity that are really four. One can forget that he is impure and
eat sacrifices or enter the Temple – these are two. The other two are
when one remembers that he is impure, but forgets that these are
sacrifices that he is eating, or that it is the Temple area that he is
entering.” We know however that Rabbi Akiva does not make one liable for
the second type of unawareness.
Counter-argument:
We could still say that the ruling is in agreement with both Rabbi
Ismael and Rabbi Akiva, but that for the other two transgressions one is
not liable to bring a sacrifice, but only to receive lashes.
Art: Isidor Kaufmann - Discussing The Talmud