Why I think Slavery is maybe not the right word:
1. It is surely a researched "technology", not something you start the game with in 10,000 BC.
2. It becomes obsolete as a nation industrialises. The countries in the modern era which still have slavery lack fully developed Social and Economic Infrastructures - slavery is displaced by Indenture, and as the taxation and financial systems and services become more sophisticated slavery becomes anachronistic and unprofitable.
3. The other issue is "types of slavery"; you have traditional ancient world slaves which are commonly understood, then you have: human trafficking, and prostitutes; people who are kinds of slaves because of who they are: women, children, racial groups, religious groups, social castes, economic classes.
What does the position on the slavery slider mean? is it the amount of slavery, or the extent of the slavery? is it the level of oppression?
Are the citizens of North Korea slaves? (ie. would the slavery slider be up at 90+%?), I can see how it makes sense under an ancient feudal government, but what about 20th century regimes?
I would be interested in seeing some example tables for different states we know, to see what they look like in game terms, that'd help illustrate the way this preferences box works.
You might opt for "Personal Freedom".
Could try "Liberty
" perhaps? "Egality" (something the French should know about!); you could be more positive, and call it "Emancipation"!
The Executive is surely both
the decision making collective noun, and can be used to descrive the leader's position.
Clergy is a good term, as it's not attatched to any religion. Philosophy and Religion are probably best treated as one thing in the game, the lines between them can be blurred, particularly in far east "religions".
Human = The People... I still don't get what you mean precisely - what's all this about the "Capitalists" then? - I would naturally be inclined to go for the termThe Public
regardless. It just feels more appropriate.