Dear C. G.:

You wrote:
Can you tell me if the following sentence is correct?
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> It’s a quality William Penn lauded before the founding of the republic when he encouraged citizens to show any kindness they can for their fellow humans.
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> Some of us in the office think the word “can” should be changed to “could”. What is correct?
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>
Either one is OK. “Could” is conditional; “can” is indicative. Using “can” would imply that you are able to it at any time. Using “could” would suggest you can do it under the right conditions. The difference is subtle, but knowing Penn (he coined the term “No cross, no crown”–the original “No pain, no gain”), “can” would work for him.

By the way, most authorities would probably capitalize “Republic” because it is specifically named. Whichever way you choose, be consistent.