[Avodah] Vaccinations - Rav Asher Weiss

[Akiva Miller]

.
R' Alexander Seinfeld quoted Rav Asher Weiss, and explained Rav Weiss
to be distinguishing between vaccination and ma'akeh:

> He uses the example of a maaka (fence around a place where one
> could fall). How effective is this fence, assuming it is built
> and used correctly? Can we agree that it is 100% effective at
> its job of preventing falls? (Excluding building errors or
> misuse such as climbing over it)? The vaccination is not like
> that – even when made and used correctly, we still expect about
> 1 in 1,000,000 children to die from it. That’s pretty scary, and
> the ma'aka mitzvah does not readily and obviously apply here.
> The essence of a ma'aka is that it is a 100% protection against
> a possible danger (nobody knows the level of danger without a
> ma'aka, I propose 1 in a thousand (.1% percent as a good-faith
> estimate). To repeat, a 100% protection against a 0.1% risk. But
> as I've already shown, a vaccination is not a 100% protection
> and the risk is low but not zero.

R' Zev Sero disagrees with the claim that maakeh offers a 100% guarantee:

> Nothing has zero risk, or a zero failure rate.
>
> As you point out parapets have two modes of failure: defective
> construction, and people climbing over them; however uncommon
> these are, that's a non-zero failure rate; not the 2% of the
> MMR vaccine, but let's suppose 0.02%. ...
>
> Parapets also carry a minuscule risk, e.g. from people striking
> their heads against them, ...

I would agree with RZS's basic point, but I would go much much farther
than he went. The risks of a maakeh are not merely from when the
maakeh was built incorrectly (in which case it's not really a maakeh
at all), or from when someone deliberately defeats its safety features
(like when climbing over it), or from "oness"-type collateral damage
(like hitting one's head against it, in which case he'd have been
better off if there had been no maakeh at all).

Rather, I would argue that the maakeh is inherently a less-than-100%
protection, and doesn't even claim to offer 100% protection.

Mechaber Choshen Mishpat 427:5 writes, "The maakeh must be no less
than 10 tefachim high, so that a faller will not fall from it. And the
wall must be strong so that a person who leans on it will not fall."

The criterion of "leaning" seems rather weak to me. I can easily
imagine many situations where a just-barely-kosher maakeh will NOT
give 100% protection: When people are running or fighting, their
momentum is that much greater, and a maakeh that would have protected
someone leaning will be inadequate. Even a person who is walking
backwards (for some legitimate reason) may not realize that he is
close to the edge and the maakeh MIGHT fail to stop him. This will be
especially dangerous if the person is tall and/or a small shiur of
"tefach" was used for the construction.

No. A maakeh is NOT a 100% protection. It might offer 100% protection
to the typical cases, but not to the unusual ones.

Akiva Miller