Last week we were introduced to the concept of cholov akum, which is milk that was milked by a non-Jew without Jewish supervision. Chazal made a gezeirah (decree) that it is forbidden to drink this type of milk, because of the concern that some non-kosher milk was mixed in with the kosher milk.
Why would somebody want to mix non-kosher milk into the kosher milk? A plausible reason would be for financial gain, such as if the non-kosher milk was cheaper than the kosher milk. But what if the non-kosher milk was more expensive than the kosher milk, such that there would be no incentive to do this? Or what if there were no non-kosher animals in the vicinity during the milking? In these scenarios it seems very unlikely that there would be any non-kosher milk mixed in.
This brings us to a machloikes (disagreement) between the Pri Chadash on the one side, and most other Acharonim on the other. The Pri Chadash says that the gezeirah of cholov akum was based only on the concern of non-kosher milk being mixed in. If that concern goes away, the gezeirah doesn't apply. So in the two situations above, where the non-kosher milk is more expensive, or where there are no non-kosher animals in the vicinity, the Pri Chadash is lenient and permits the milk even without Jewish supervision.
Virtually all Acharonim argue on the Pri Chadash. They maintain that even though the gezeirah of cholov akum was made because of a particular concern, once it was introduced, it applied regardless of the circumstances. In this way it is similar to other gezeiros that Chazal decreed, such as gevinas akum (non-Jewish cheese), where all Acharonim (even the Pri Chadash) agree that it is forbidden regardless of the circumstances. These Acharonim who argue with the Pri Chadash require Jewish supervision of the milking every time. They would not allow consumption of the milk in the two cases brought above.
This machloikes is based on the Gemara in Avodah Zara 39b. The Gemara brings a baraisa which says that a Jew can sit next to the flock of a non-Jew (but cannot see) and the non-Jew can milk from his animals and then bring the milk to the Jew. The Jew can drink the milk and we are not concerned.
The Gemara asks: "What exactly is the case? If there are only kosher animals on the farm, then pshita (i.e. obviously it is allowed)". And if there are non-kosher animals then why is it permissible even though the Jew is sitting outside?" The Gemara answers that the case is where there are indeed non-kosher animals on the farm and the Jew is sitting outside and cannot see anything. However, when the Jew stands up, he is then able to see. Because of the possibility of the Jew standing up and seeing everything, the non-Jew is afraid and will refrain from adding in non-kosher milk.
The Gemara above says that if there are only kosher animals, then "pshita" that the milk is permissible. What exactly does the Gemara mean by "pshita"? Does it mean pshita that he can drink the milk simply because there were only kosher animals on the farm, or pshita that he can drink the milk because there were only kosher animals and he was sitting outside?
The Pri Chadash understands from this Gemara that having only kosher animals is enough to tip the scales to permit the milk, while the Acharonim who argue with him still require the Jew to be present.
Next week IY"H we will look at the famous heter of R' Moshe Feinstein regarding cholov stam.