@joefromchicago,
Joe, I like the examples you give. Let's look at the differences.
This is clearly a mathematical statement. The numbers "2" and "5" have a precisely defined meaning that you and I both understand and agree on.
Likewise the operators "+" and "=" are well defined.
This assertion is testable with an objective process... no matter what culture you are from or how you were brought up, someone who takes two objects and adds two objects is going to get four objects.
Of course you can play little mental games with meaning (and I hope you aren't going there).
But anyone can understand the difference between this example and the next one.
Quote:"it is morally wrong to kill a person without justification,
This assertion has a bunch of ill-defined terms. The word "Morally" is meaningless outside of a well defined moral system (and there are plenty of different functioning cultures that will come up with wildly different answers).
The word "justification" is a real problem.
Our society allows us to kill unborn children, adversaries at war, and people convicted of serious crimes. We don't allow people to kill the man who slept with their wife. We don't kill the aged. And we don't consider any political idea dangerous enough to justify killing.
All of these things are beliefs I agree with-- and assuming that you are in the same culture and had a similar upbringing as me, I would not surprise me if you agreed with me on all of these points.
But in each of these points, people of other cultures and times have had opposing views.
Here is the challenge...
Take any item in the list of what "justified killing" entails or doesn't entail and provide a mathematical or scientific argument for your position. I don't think there is an objective rational proof of any one of them that doesn't rely on an unprovable assertion that isn't accepted by other human beings.