What is the reason for the many
disputes over establishing an eiruv?
In times when people lived in small villages and small towns,
erecting an eiruv was much simpler than it is now. Setting up
an eiruv in large cities with millions of people is far more
As mentioned in previous shiurim, the eiruv we set
up nowadays, which is comprised of many tzuras hapetach, is
only effective around an area that is not a biblical public domain (reshus
harabim d’oraisso). Such an area must have its entrances closed
with doors or gates, which is not practical.
What defines a reshus harabim
There are two opinions in the matter. One opinion holds that an area
that has streets 16 amos wide (approximately 29ft, or 9m) is
a reshus harabim, while others hold that this area must also
contain 600,000 people.
to the stringent opinion, most of our towns and cities have streets
that are 16 amos wide and thus are a reshus harabim.
However, even that is not so simple, because there are opinions who
maintain that if streets curve and turn, the buildings or fences on
either side form mechitzos (walls) which negate the presence of a
Another problem is how to define the presence of 600,000 people.
What if they do not live in the given area and only pass through?
What if they pass through a certain section of the town, does that
render the entire town a reshus harabim?
Due to these complexities, it is not a simple matter to define
whether certain areas can be surrounded with a tzuras hapesach
What are the other problems?
There are the acute complications in setting up a tzuras hapesach.
Even if it is taken for granted that a given area is not a reshus
harabim d’oraisso, the various opinions defining the halachos
of a tzuras hapesach are numerous.
Due to these complications, we have conflicting opinions whether one
can or should make an eiruv in large cities.
Obviously our intention is not to take sides in any matter; we are
merely presenting a minute proportion of the complications involved
with setting up an eiruv. One must always ask one’s rav
whether it is permitted to carry within an eiruv.
Is there a limit how far one may
walk on Shabbos?
Chazal said that one may not walk more than 2000
amos (approx. 1km, 0.62 miles) outside the perimeter of a town.
This has nothing to do with an eiruv. This too is complicated
as to how and from where to measure this distance.
Basically, a town is squared and the 2000 amos are measured
from the square.
square is formed in which one may walk the entire square. This means
that from the town to the corners of the square one may even walk
more than 2000 amos. One may also walk more than 2000 amos
within the square, provided that one does not walk outside the
square or t’chum.
Is there a way to lengthen the
If one wishes to walk further than 2000 amos, one may do so
provided that one placed an eiruv t’chumin at a certain point
outside the town. This will entitle the person to walk 2000 amos
in any direction from the eiruv t’chumin.
Very briefly there are two methods. One must be at a point close to
the end of the original 2000 amos for the entire bein
hashmashos (twilight). After nightfall one may return home and
one’s starting point is now the place he was at before. As a result,
one loses the 2000 amos on the opposite side of the town
because the starting point is not the town, rather the point on the
The other method is to place food equivalent to 18 dates, at that
particular place. That point is now the starting point and the same
Obviously one cannot learn from these few lines and when the need
arises one must thoroughly learn the halachos.
If a person in a desert does not
know when it is Shabbos, how must the person conduct himself?
The main problem is that since the person does not know when it is
Shabbos no melacha may be performed lest Shabbos be violated.
As such, the person must deplete any provisions and subsequently
melacha may be performed in order to survive, such as hunting
etc. but only for that day. Additional melacha may not be
performed on one day for the morrow lest that day is Shabbos.
From the time it is realized that one does not know what day it is,
seven days must be counted and on the seventh kiddush is
recited and havdala, in order not to forget the idea of
Shabbos. On that day melachos may be performed as well in
order to survive.
The person may walk as much as necessary – even more than 2000
amos – because it is vital to try and find civilization in order
Several halachos have been omitted from this shiur and one
may learn them in simon 344.