[KJacob]

Let's start with an easy one--duty to perform contracts. People are free to enter into, or refrain from entering into contracts. But once in a contract, they are not free to fail to perform.

I agree

not treating other people as simply means to our ends but as people who have ends of their own

Not something that can be enforced.

His list of duties includes helping others when you can (duties of beneficence, Ross calls them), to develop our own talents, and to not commit suicide.

People cannot be forced to do any of these things without losing a lot of freedom. I will agree that if more people did these things (of their own freewill) the world would likely be a better place. But any attempt to force this behavior is frankly wrong.

[rogerv]

Some of this can be enforced surely. We have laws (in fact, a constitutional amendment) against slavery. And we have laws against abusive treatment in the workplace by superiors.

As for the enforceability of beneficence, you are right for the most part. We do not have laws forcing people to be good Samaritans. But, on the question to which we are heading at some point, there is a question about the production of public goods by government with our tax dollars. It is a question we ought to discuss: which goods count as public goods we would want government to produce, even if we were not direct beneficiaries?