Moreover...
Moreover, from the first the Shia have agreed on the permissibility of Mut'a, to such an extent that this view has always been singled out as one of the specific features of Shia. Given this fact, to claim consensus is meaningless. In addition, as we have seen above, many of the Prophet's outstanding and their followers held that Mut'a was permitted. Finally, the claim that Ibn Abbas changed his view on Mut'a toward the end of his life has never been substantiated.
Even if it were to be proven, one could only claim consensus if we were certain that no one was opposed to the view that Mut'a is forbidden; whereas we know that in fact the number of opponents was quite large. In short, the Shia conclude, there is no real evidence to show that Mut'a is not permitted; and when the Hadith are investigated, the conclusion is likely to be reached that not only is it permitted (Mubaah), it is even recommended (Mustahabb).
The Opinion of the Four Sunni Schools of Law The four Sunni schools of law agree that temporary marriage is invalid. That which invalidates the contract is the stipulation of a time period. If such a marriage takes place, it must be annulled, and if it is consummated before the annulment takes place, the woman must be paid the "normal dowry".
The Shafi'i school adds that even if the time period stipulated by the contract is the life-time of the husband or the wife, the contract is still invalid, since the contract of marriage requires that its effects continue after death. That is why a spouse may give his or her spouse the ritual purification of the dead before burial (otherwise, the washer of the dead must be of the same sex as the corpse).
A marriage contracted with a stipulation that it comes to an end when one of the spouses dies would mean that the effects of the marriage would end at death. So such a stipulation invalidates the contract. The Hanafis add that if the time period stipulated is so long that as a rule the spouses could not remain alive until it comes to an end (e.g., if the man were to say: "I will marry you until the hour of Resurrection"), then we can no longer call the marriage "temporary".
in effect this stipulation means forever. Hence it is not considered as a stipulation of a time-period and the contract is sound. If the husband's intention in contracting the marriage is to enjoy the woman's company only for a period of time, but he does not make such a stipulation in the contract, the marriage is correct.