In American law, we look to what is private, as opposed to public, by asking where we have a reasonable expectation of privacy. If there is an area (or device) where we have a reasonable expectation of privacy, then the general rule (with enough exceptions to make a Talmudic tractate), is that the government cannot intrude in this private area without a warrant based on probable cause. The Talmud has a close, but mirror, concept: for an area to be public, it must be normally used by the public. For this reason, the open seas or fields, which are accessible to the public, are not actually public domains. The Rabbis decreed them to be a third type of space, Karmelis, meaning semi-public. While one can violate a rabbinic prohibition by carrying from a Karmelis to another area, one does not violate a biblical prohibition.

Today’s Daf continues our detailed exploration of the ragged edges between different domains, so that we will be able to properly discern which domain we are in and when we have committed the forbidden Shabbat labor of carrying. Again we explore hypotheticals that can seem downright ridiculous given their improbability, but you have to remember what we are trying to accomplish. We are not trying to know the rule for the specific situation, rather we are learning to apply the rule in novel situations so that we can properly analyze God’s laws when we face another situation that we did not contemplate.

We actually begin with a concept that has surprisingly wide acceptance amongst our sages. To be carrying, there has to be lifting and placing down. We do not lift an object or place it down if the surface from which we are lifting or to which we are placing is so small that we can’t really say the object is resting. We consider an area below four Tefrachim (14 inches) to be too small for an object to be considered resting. We learn, however, that this only applies in a public domain. In a private domain, we don’t need an area of four Tefrachim to have carrying. Any area will do.

Once we establish our agreed principle, we immediately debate what the limits of this principle are. We start with a tree whose trunk is in a private domain, but whose branches extend into the public domain. Consider a tree in a walled courtyard, with branches extending into the street. We do not get unanimity on how to address this situation.

Next, we consider tossing a container from the private domain to the public domain. We need to consider this case, because forbidden Shabbat labors are derived from the activities necessary to construct the sanctuary in the desert. Apparently, craftsmen would toss small tools to each other. If a container is large enough, it is a domain in its own right and craftsmen did not toss containers to each other. Therefore, we need to explore exactly what is large enough (depending on the shape) of the container.

The idea of a public space needing to be useful to the public comes into play when we consider a pole in the public domain. We have a general rule that areas above three Tefachim high in a public domain are not actually public, because they are not used by the public that much. A pole ten Tefachim high is not public because public airspace only extends ten Tefachim. The Rabbis consider a pole nine Tefachim high. It is in the public domain. It is higher than three Tefachim. However, in this instance the Rabbis conclude that it is useful to the public for adjusting loads and therefore should be considered public. (To be honest, I am struggling to understand the adjusting loads point).

Since we considered a pole extending nine Tefachim above a public domain, we should consider a hole extending nine Tefachim below a public domain. The public could use it to store stuff, so we should consider it public.

We then consider the case of an Eruv around a pit. An Eruv is an enclosure that is used to create a normally public space into a private domain for Shabbat. Our whole next tractate will be on the rules of Eruvim and I am not that familiar with the requirements. Today, we look at an Eruv in a pit. An Eruv has to extend ten Tefachim up. If it is in a pit, where do we measure ten Tefachim from? We also consider rolling. Is rolling carrying?

We then turn back to thresholds. Remember, a threshold is neither public nor private. However, we cannot have someone stand on a threshold and act as a bridge between someone in the home and someone outside to get around the laws against carrying. The Rabbis want to know if three people do use a threshold as a bridge to transfer an object, who is liable? Our Daf ends before we get the answer to that question.