This is another concept, Shmoopers. But, like the above, it's uber-important.
As the title suggests, Thomas Paine bases the arguments in his pamphlet on the concept of common sense. In other words, he doesn't use a whole bunch of overblown language or fancy literary references to get his point across.
Instead, he speaks in language anyone can understand and lays out his reasons for things one by one. All the while, he says,
To examine that connection and dependence, on the principles of nature and common sense, to see what we have to trust to, if separated, and what we are to expect, if dependent. (3.6)
In other words, he expects every one of his readers to think carefully about what he's writing and judge for themselves whether they come to the same conclusions.
At various points in this book, Thomas Paine assures his readers that the only thing informing his opinions is good common sense. He makes sure to deny any other motives when he says,
I am not induced by motives of pride, party, or resentment to espouse the doctrine of separation and independence. (3.30)
For him, American independence is a matter of pure reason, and not one of petty emotions. That's why he believes the cause of independence will endure until it's fulfilled.