Rene Descartes had the best opening line in the history of philosophy: cogito ergo sum (I think, therefore I am). That was his starting point for constructing a philosophy – the one thing he could be sure about was that he was cogitating.
I have a different starting point. Mine is to ask: what matters? Why does it matter? What does mattering mean? After all, if something doesn’t matter, then why think about it at all?
The three questions turn out to be really one question, with one answer. What matters, ultimately, is what sentient beings feel. It matters because there just isn’t anything else that could matter. If there were no sentient beings to experience joy or suffering, then whether or not the universe even exists wouldn’t matter. Because for something to matter, there has to be someone to whom it matters. Otherwise the concept of “mattering” makes no sense. “Mattering” means mattering to someone.
By “sentient beings,” I mean beings with consciousness – self-awareness, with the capability to experience feelings, such as suffering or joy, to know they are being experienced, and to respond to the feelings. The prime example is a human being. It would include some other higher animals (say, elephants) as well, that experience such feelings. It would not include clams, insects, or trees. And certainly not rocks or rivers or planets (sorry, “Gaia” people, the Earth is not sentient).
Some people have big cosmic beliefs. Okay; believe what you like. But nothing there can matter to human beings unless, in some way, it has an effect upon feelings that take place in human minds. If it doesn’t, then even if the belief is true, it’s an irrelevance.
The foregoing gives us the foundation point for a philosophy that matters: everything is judged by its effects upon human feelings, whether positive or negative, conducive to suffering or joy. What we do affects human feelings, our own and those of others. This is the way in which our lives matter, and have meaning.
There is nothing else.