Berakhot 141

1:
This mishnah continues the exposition on differences of custom between the two schools – and the subject is still Kiddush. Bet Shammai say that the hands must be ritually washed before reciting Kiddush, while Bet Hillel say that the ritual washing of the hands comes after the Kiddush.

2:
The Pharisaic movement divided the Jewish world into two groups: those who observed the minutiae of the Levitical laws of purity and separation of priestly dues from produce – and those who did not do so. The latter were termed Am ha-Aretz ['peasant'] and the former were termed Ĥaver ['colleague']. One of the basic assumptions of the laws of Levitical purity is that uncleanness is contagious and can be passed on from person to person, from person to object and, thus, from object to object and object to person. While I am not for one moment suggesting that there is any basis for an assumption that the sages were aware of the existence of 'germs', I think it can be helpful to use our modern knowledge of the way disease is communicated in order to understand the mentality of the rabbinic concept of contagious ritual impurity.

3:
The sages recognized a classification of primary, secondary and tertiary infection. Primary infection rests in a sheretz (for the sake of simplicity when the topic is not essential to our discussion, let us call a sheretz an insect). That primary source can pass on its infection to a secondary source through physical contact, and the secondary source can similarly infect a tertiary source.

4:
According to the sages, unwashed hands are presumed to be in a state of (secondary) ritual impurity. It is inevitable that when pouring wine and water generously into a cup that drops of liquid will accumulate on the outside of the vessel, which has been filled to overflowing. When unwashed hands come into contact with these drops of liquid their ritual impurity will be transferred to the cup. This is a situation that the view of Bet Shammai in our Mishnah wishes to avoid. The Gemara [Berakhot 52a] objects that one's hands are at the most in a state of secondary infection (they are not the insect itself, but may have been infected by one with ritual impurity). It is then explained that because of the intricacies of the laws of ritual impurity, what concerns Bet Shammai is that the secondary infection of the human hand when it comes into contact with a liquid, will pass on the impurity to the cup through the agency of the liquid.

5:
Bet Hillel take a completely opposite view. According to them a ritually impure cup may be used for Kiddush. If you wash your hands before touching such a ritually impure cup the residual moisture on the hand will serve as an agent for transfer of the impurity on the cup to the person. (And, of course, such impurity will subsequently be transferred to the food eaten, and so forth.) Since a dry hand coming into contact with a ritually impure Kiddush cup cannot contract ritual impurity, it is best to ensure dry hands by postponing the washing of the hands before a meal until after Kiddush. Such is the view of Bet Hillel.

6:
Established custom nowadays is – of course – in accord with the view of bet Hillel: first Kiddush is recited and then the hands are washed before the meal.

In Berakhot 134 I wrote that Washing one's hands before eating bread is a halakhic requirement that is rigorously applied. The berakhah "Ha-motzi" should not be recited by someone who has not washed their hands, and even if they respond to the berakhah of someone else who has washed their hands this will not avail them from the halakhic point of view.

Ron Kaminsky has several questions about this.

1. It is not possible to count the person for zimmun because he is not halakhically required to say Birkat Ha-Mazon In other words, washing, Ha-motzi, and Birkat Ha-Mazon are all so linked halakhically that they must all be done or none of them be done?

I respond:

No, they are not linked. Someone who has not washed their hands before eating is still required to recite Birkat ha-Mazon.

2. If someone is in a situation where it is simply not possible to wash (prisoners, people lost in deserts, etc.), what is the halakhah?

See my above response. However, in this connection I always recall the beautiful story told about the incarceration of Rabbi Akiva by the Romans prior to his execution for the crime of having taught Judaism publicly.