This is why secular, Thanksgiving-flavored gratitude seems so fuzzy. Religions from Christianity to Hinduism to Wicca all emphasize the importance of thankfulness, especially as a form of prayer. This is because they rely on the premise of an other, some sort of non-human being that has some sort of control or influence in the world who you can thank for the world and the good things in it.
"One of the things that’s really interesting about the human mind is that we seem to want to see agency in the world, almost intuitively," said Michael McCullough, a psychologist at the University of Miami. "The mind really craves an explanation for the good and the bad, in terms of agency."
By "agency," McCullough means something along the lines of "a force that can act in the world and cause events to happen." In crude sociological terms, people give thanks to the forces that act in the universe—God, or god, or gods—as a bid for cosmic benevolence, whether that means making it rain or preserving a loved one's health or bringing a baby into the world. But these thanks are also an implicit metaphysical claim: Humans owe their existence, their longevity, and perhaps even their daily fortunes to a being beyond ourselves.
But if you take all of that away—either because you don't believe it, personally, or perhaps because metaphysics isn't really something you can talk about at the Thanksgiving dinner table—what does gratitude actually mean?
"Let me explain something about gratitude," wrote Robert Emmons, a psychologist at the University of California, Davis, in an email.
We all begin life dependent on others, and most of us end life dependent on others. If we are lucky, in between we have roughly 60 years or so of unacknowledged dependency. The human condition is such that throughout life, not just at the beginning and end, we are profoundly dependent on other people. ...
Gratitude is the truest approach to life. We did not create or fashion ourselves. We did not birth ourselves. Life is about giving, receiving, and repaying. We are receptive beings, dependent on the help of others, on their gifts and their kindness.
"You see—none of this have I framed in a religious context or using religious/spiritual language," he concluded.
But commenting on the human condition and the nature of life is at least philosophical, if not spiritual, and it's certainly normative. Since humans are born, survive off the generosity of others, and then die, he's saying, gratitude naturally is and should be the organizing principle of life.
But this isn't obvious, necessarily. In the Genealogy of Morals, for example, Friedrich Nietzsche condemns the "slave morality" that underpins values like humility—this way of thinking undermines individuals' recognition of their power, their sense of independence, he says. Human civilizations—and individuals—don't necessarily have to organize themselves around gratitude and interdependence.