Lifnei 'Iver in public policy/business

Question

How far does Lifnei 'Iver extend? Earlier versions of this question led to a good deal of speculation of how an individual should respond to issues of public policy and business that may be contrary to Halachah.

But I wonder if the basic premise starts with Lifnei 'Iver or if a different issue, perhaps just about trying to create a better society (and what that means is its own question, perhaps), is really at the root.

So here's the question:

Does Lifnei 'Iver even apply when it comes to one's taxes and immediate business functions that are removed from, say, immediate sale of a product or immediate employer/employee functions (like forcing an employee to overcharge or deceive a customer)?

Less controversial examples of potential Lifnei 'Iver implications, if it does apply:
* Government engaging in unjust wars
* Working as a marketing executive for McDonald's Corporation
* Working on the campaign of a political candidate who holds some views that are contrary to Halachah (or even one such view).

Answer 1

In all the cases specified there is no Lifnei Iver.

The Gemara (Avodah Zarah 14a) says:

Said Abaye; We should be particular not to [place a stumbling-block] before [the blind] but we need not be so particular as to avoid placing it before one who may place it before the blind.

The simple explanation of this Gemara is that Lifnei Iver does not apply when one is more than one step removed from the one committing the prohibited act. This particular halacha is codified in Shulchan Aruch YD 151:1, and if you'll look at the Pischei Teshuva there he clearly understands this explanation to be correct.

That being said, one should always be concerned about how one's actions will be taken by the world, and if people will look at what one does as an endorsement of something which is against the Torah, that could be a terrible chillul Hashem depending on the person, regardless of whether or not there is a Lifnei Iver involved. So proceed with caution.