But where does the idea of rewarding the productive have its roots?
Let me look around a bit.
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Proverb 22: 16 Proverbs 31:31 James 5 : 4 It is a bad idea to withhold earnings from someone who has earned them.
1 Kings 11:28 Promote the talented.
Proverbs 12:14 Proverbs 14:23 Proverbs 16:26 Proverbs 18:9 Proverbs 21:25
Proverbs 28:19
Don't be lazy
1 Chronicles 4:10 Pray for success.
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I didn't find direct support for the idea with a cursory scripture search , I found a few things that support it tangentally.
I don't know the real origion of enlightened self intrest tho I suspect it is older than Adam Smith.
Smith wrote: "How selfish soever man may be supposed, there are evidently some principles in his nature which interest him in the fortune of others and render their happiness necessary to him though he derives nothing from it except the pleasure of seeing it."
http://www.econlib.org/LIBRARY/Enc/bios/Smith.html Perhaps the best reson to allow Lazie Fare economic rules is that they work better than the alternatives we know of in terms of the greatest benefit to the greatest number. It seems to be the rule in modern times and anchient that a land with few rich has plenty of poor and that a land with many wealthy still has the poor but they are not as poor as they would be with out the presence of the rich.
I feel as though some people would level the playing feild to the point that everyone was earning the same wage even if they knew for a fact that this would cause famine.
I am gonna have to admit tho , that I can't really answer the question you asked.