[Avodah] : kosher switch

[Chana Luntz]

> On Tue, Sep 27, 2011 at 09:55:49AM +0100, I  wrote:
> : But, it seems to me, the more innovative bit about this kosher switch
> is the
> : introduction of randomness.  The point being that, if you toss a
> coin, you
> : have a 50% chance of not getting a head.  If you toss it again, then
> you
> : only have a 25% chance of not getting a head on one of those two
> times.  If
> : you toss your coin again and again and again, the chances of you not
> getting
> : a head at least once gets smaller and smaller and smaller.  BUT the
> chance
> : that you never get a head remains (and will remain until infinity).
> So in
> : theory this kosher switch might *never* work, it just means that the
> : probability of it never working gets smaller and smaller and smaller
> the
> : longer time goes on (and the more coin tosses are done)....

And RMB replied

> At some point, the probability gets to be a small enough miut that it's
> ignorable.

Why?  If at any given point, you still have only a 50% chance of getting a
head?  

> IOW, I don't think being goreim something that rov of the
> time violates an issur is any more mutar than geramah of a vadai.

Well clearly there is such a concept - that is precisely the din of psik
resha.  If you want to do something mutar (eg move a bench) but your act
will vadai perform an unintentional issur (such as create a furrow) then it
is assur, if not, then mutar (even if you might create the furrow rov of the
time). The point is that if you cut off a chicken's head, it is vadai dead.

Now there we are dealing with a vadai act, just a lack of intent for the act
that constitutes the issur, eg the creation of a furrow.  Here the intent
for the result is there, but there are all the other aspects that arguably
make this into a grama.  And then layered on top is the lack of certainty
that anything will happen at any given moment.

> And even if there is a difference of which I'm unaware, how big of a rov
> can one not treat the same as vadai?

Now surely the same question has to be asked regarding psik resha.  (Of
course, the whole discussion about whether you indeed can have a live
chicken without a head presumably feeds into this - given the reported
reality of chickens without heads, does one not have to say that psik resha
has to be 99.9% at most (or whatever the figure is)).

> I think that threashold of nearly-always would be crossed relatively
> soon after flipping the switch if the manufacturer wants something
reliable
> enough that people would use it.

Indeed, as you can see from the figures, it would most of the time - but not
all the time, and at each moment in time, the chance would only be 50%, due
to an independent toss.  And the toss that might cause the thing to work has
not happened at the time you mechanically move the bit of plastic.  The only
thing that is working continuously is the coin toss generator, and that has
been working since erev shabbas, tossing coins, whether the bit of plastic
is moved or not.  It is only once you mechanically move the bit of plastic,
and then the coin toss generator does a coin toss, and if it then lands on
heads, the landing on heads causes the thing to work.  No heads, no work.
So why is not the correct analysis that the thing that actually does the
issur is the landing on a head, not any preliminary movement you do with the
plastic, and this head landing does not happen until after you have moved
the plastic, and in addition its arrival is by no means guaranteed,
certainly in any time frame?

The reality is that if this is your only option, you put up with things not
working on shabbas as smoothly as they do on weekdays.  I guess unlike most
of the rest of you, I work with a grama switch on a regular basis -
precisely because, as I have mentioned on this list before, I have an
extremely disabled son, who at aged 10 is too heavy to lift (even from his
wheelchair to his bed to change is nappy, not to mention take up the
stairs).   That means that, unless you are proposing that he should lie in
his bedroom for the 25 hours of shabbas (not to mention the three day yom
tovim we have just had) but then how would you feed him?  Or sit in his
wheelchair for that period, but then how would you change his nappy? We need
some sort of mechanism to get him from food to nappy change/bed and back.
We therefore have a Tzomet installed (well actually, Tzomet designed,
English lift manufacturer input and installed (we couldn't afford to
invalidate the warranty on the lift) Tzomet checked post installation) grama
switch on our lift.  It is both a life saver and a pain.  One of the
pleasures of motzei shabbas is pushing the regular switches again, which
give one the instant gratification that one is used to in electrical
appliances.  Nobody in their right mind uses the shabbas switches when it is
not shabbas or yom tov.

(Of course these work arounds are not just with grama.  We talked to Tzomet
about modifying our ceiling electric hoists so they could be used on shabbas
to hoist him from his wheelchair to the bed and back again, but we felt that
the grama solution they were proposing was quite dangerous in the context of
the hoists we have installed, as we couldn't see how, even with a seven
second delay (which is the minimum I believe they work with), we could stop
the bar of the hoist thumping down into him and potentially seriously
hurting him (the way they work during the week, you have continuous control,
you press up or down and keep pressed until you need it to stop, when you
immediately release).  We therefore purchased (isn't it amazing what you can
find on ebay!) a portable manual hydrolytic hoist which we use on shabbas
and yom tov.  This is, however, also both a life saver and a real pain.  It
is bulky and takes up room, it is not nearly so manoeuvrable and when
hoisting from the floor is very difficult to get the sling straps on (and
involves pulling him to almost sitting position, which is not great on our
backs either).)

But getting back to the grama switches, part of what is frustrating about
the lift is that you need to push a button to open its door (if not open),
put him in it, push a button to close the door, then push a button to send
the lift up, once the lift is up push another button to open the door and
take him out of it.  Adding additional delay at every step means a lot of
delay in the end (I tend to stand there with my head in a book, waiting).
However, the first push is not too bad, because you allow for the delay, ie
you go push the button to open the door *before* you wheel his wheelchair
round from the shabbas table to where the lift is.  Similarly, if you were
allowing for a reasonable time delay, you would push the switch a reasonable
amount of time before you really wanted it, so I think it would be a
reasonable adaption to make.  However, I suspect there would need to be a
certain level of willing before such adaption would be made (ie your "non
religious Jew" would need to at least be non hostile before they would be
prepared to use it). 
 
> GCT!
> -Micha

Gmar chatima tova

Chana