[NoPicklez]

Because the good bacteria present in the milk is commensal, but the bad bacteria introduced outside aren't.

[maxerickson]

Commensal means something like "not harmful" rather than "good". It's interesting that the language of raw milk has adopted such a precise term.

[NoPicklez]

My point being that if raw milk has bad bacteria introduced from outside of the cow and it is not pasteurized, that bacteria has been shown to be harmful for us