As I've discussed with my students, it's my opinion that metaphysical naturalism entails nihilism. Naturalism is the view that the natural world is all there is, that nothing else exists beyond the physical, material world of atoms and molecules.
It's the view, in the words of Carl Sagan, that "The cosmos is all there is, all there ever was, and all there ever will be." Nihilism is the view that nothing in life matters, there's no meaning nor value, especially moral value, to be found because there's no basis for it if naturalism is true.
A student linked me to a short, six minute video in which the producer takes note of viewer complaints that the nihilism of his previous videos was too existentially depressing. He therefore seeks in the present video to offer a more optimistic, upbeat version of nihilism. It's not clear that he succeeds, or that he even could succeed.
The first three minutes or so are given to an elaboration upon the reasons for thinking, on naturalism, that life is meaningless. The narrator then gives the viewer a "pep talk" on how we should respond to our bleak existential condition. In short, the message is that there's no real point to anything we do in this godless universe, but we should try to make the best of it anyway:
The points made throughout the video, once one gets beyond the happy talk and thinks seriously about them, are melancholy. Here's a recap:
Nothing we do matters, the narrator asserts, but that means that all of our mistakes, blunders and bad acts don't matter (3:50). If this is true, what follows is that there's no reason not to yield to temptations to do bad things. None of those bad acts, acts which harm others, for example, really matters and there's no eternal accountability for how we live so why should we not do what we desire to do?
The video claims (4:05) that our individual life is all that matters, but, if so, what's being offered to us is a justification for egoism, the view that I should always put my own interests ahead of the interests of others. On egoism what's right is what gives me happiness, satisfaction and pleasure and what's wrong is whatever diminishes my happiness, satisfaction and pleasure.
Every tyrant was an egoist, every act of barbarism and evil was done by people who were putting their own interests first. If our life is all that matters then might makes right and whatever someone has the power to do would not be objectively wrong to do no matter how much it harmed others.
This egoism is evident in the narrator's rather preposterous claim (4:15) that we dictate the purpose of the universe.
The narrator goes on to insist that life doesn't matter, but that we can insert meaning into it by having good feelings, and experiencing nice things like music, friends, and video games (4:30). We should take consolation from the fact that we are part of the universe, the thinking part, but how this can be consoling is hard to see.
It's a bit like encouraging a dying friend to take comfort in knowing that soon as his body disintegrates his atoms will be recycled into the earth and perhaps eventually be taken up into some other living thing.
In sum, do good things, have fun, be happy and try to make others happy (4:55). Do whatever makes you feel good, and you get to decide whatever this is (5:45). Of course, if this is so, then no one can say that the person who feels good by raping, torturing, stealing, and lying is doing anything wrong. After all, we get to decide what makes us feel good and none of our bad deeds matter anyway.
Such is the world that the "optimistic nihilist" would have us inhabit, but, in fairness to him, it is indeed the best he or anyone could come up with if naturalism is true.