Background: there is, of course, a Biblical injunction that touching something that touched a corpse makes one ritually unclean. This does not apply to the ground, and, by extension, something like a clay oven built directly out of the ground can touch a corpse and still be fine as far as ritual purity goes. (Whether or not you want a corpse on your oven is a different question) However, what about a clay oven that's been transported and is sitting on the ground but no longer part of the Earth itself?
So Rabbi Eliezer defends his Oven of Serpents and Rabbi Yehuda condemns him for it. Rabbi Eliezer performs several miracles and even gets the Lord Himself to endorse his position, but Rabbi Yehuda reminds God that He doesn't have the ability to go back on the Torah now, reminds Him of Deuteronomy 30:12 "It is not in heaven" and points out that His own Scriptures had said "After the majority one must incline." (Exodus 23:2) The Rabbis effectively outvote Rabbi Eliezer by pointing out that he's in a minority of two on this issue: him and God.