Selling something you didn't know was illegally polluting is a large distance away, legally, from designing the system specifically designed to break the law.

Do you really think VW salespeople should go to jail for this? Should salespeople do their own emissions testing? Should they all buy multiple versions of the same car and crash it to see if it's really safe? How does that system work? VW has a clear set of emissions rules to follow because they build the cars, why should the salespeople be on the hook? This isn't Tesla, VW salespeople don't even work for VW.

"One man's modus ponens is another man's modus tollens"

He's proposing a Reductio Ad Absurdum argument, implying strict adherence to the "fall on the sword" principle causes prosecution of salespeople.

Because there's an implication, if you accept his argument, then you either reject strict adherence to the principle(modus tollens) or accept prosecution of the salespeople(modus ponens).

You interpreted his comment as accepting prosecution of the salespeople, but I believe he intended you to conclude rejection of strict adherence to the principle.

Yes, thank you.

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Thank you for that piece of information. I did not know that it was called that. Very interesting.