Justification: Example

I tend to be nice because it works. I can come up with rationalizations and reasons about why nice is better than nasty-- better for me and for society. But I don't think, deep down, that is what is going on.
I can be a dick. There are times when it is appropriate and works, but those times are relatively rare. I tend to be nice instead. Not because of any big ideals. No global ethic or right-or-wrong. Not even because being nice is a more effective strategy more often. Those things may all be true. I believe they are. But they are the rationalizations and justifications, not the reason.

Being a dick increases friction. It makes my life harder. My human brain has reasoned out all the other stuff I said above. A turtle wouldn't need any of that. 'Life is easier' is reason enough.
It's not universal. Some people eschew the 'nice' strategy and go for the 'jerk' strategy because it works-- for what they want or want to avoid. Some like friction. Some are jerks to get left alone, which also decreases friction. Some enjoy even negative attention. And being nice and having friends does take effort.
No two people like or value the same things in the same way. Did you automatically try to figure out a 'why' for that? Nature? Nurture? Seeking justification? Is the simple truth that people are different too simple?
Some people look for attached meanings, and see them for what they are. Same with attached reasons.
Or...