This was meant to replace Fiducial Utilitarianism. I think it improves it in some ways, but I'm okay with the older version, too. This one only focuses on "fiducialism", while the other one talks more about utilitarianism as well. This booklet may also be helpful to read on the subject.
"Fiducialism" is my term, borrowing from Joseph Godfrey's (or some source of his's) term "fiducial", which means "pertaining to trust". Fiducialism is when we seek to trust. Hedonism is when we seek positive experiences, but fiducialism is when we seek to be receptive to some kind of positivity ("receptivity to enhancement" is Godfrey's definition of trust, in his Trust of People, Words, and God). I don't remember Godfrey's take, but I think "enhancement" can be defined as broadly as "well-being". If I am receptive to something as though it it is making me better off in some way, whatever definition of "better off" I trust as true, then I am trusting it.
Trust is personal connection. We trust the chairs we sit in, and the ground we walk on. We trust ideas -- even ones that in a sense we distrust. Just by thinking them enough to disagree with them, we trust them. We connect with their reality. We are receptive to what comes our way through these connections.
Some things inhibit trust. An "insult to the organ of trust" ("insult" in a medical sense) can be called a betrayal. A betrayal can hinder a person's ability to trust, either temporarily or permanently. We avoid betrayals so that we can trust more. Inhibiting trust in a betraying thing (a prudent behavior) helps us to trust more in the long run.
Part of trusting more is to trust more and more things. Or, perhaps more precisely, to be capable of trusting more and more things. What's important is to develop the receptivity. It's important to go out and experience the world so that you open yourself up on the inside. But when you have experienced enough, you don't need to keep experiencing things. Then you can rest.
It's important for a fiducialist to trust the set of all things, to have an overall trust. Godfrey calls something like this "security trusting" (trusting what is, over all, to be good in the end for you) and "openness trusting" (you approach reality as something which can give you opportunities). Security trusting and openness trusting are part of everyone's lives to some extent, whether or not they officially acknowledge them or know how they might be rationally justified.
I think that altruists are people who trust, who personally connect with reality other than themselves. Trusting brings life to people. Trusting preserves personality, because it is you, the person, who trust. A hedonist could cease to be a person in that emphatic sense, as they may be passively fed positive experiences. But fiducialists themselves trust whatever experience they have, to the full extent that it is trustworthy.
We need to open up to this or that thing, but one reality we need to open up to is "the best". Strangely, we don't have a taste or a stomach for the best, at least, not always developed to its full extent. So to be a fiducialist, we have to seek what is highest, deepest, and truest. A fiducialist can't avoid what is best, hoping to only trust the easier things. Trusting can be difficult and costly.
The very idea of maximization, at the heart of utilitarianism, can come out of a receptivity to "the best".
Fiducialism could be considered a definition of instrumental rationality, just like hedonism. It inherently disposes us to connect with the truth, which is like "the best", or is part of "the best". So it is a good grounding for epistemic rationality. Hedonism allows us to go into the experience machine, but fiducialism wants to be open to what exists. It does not force us to connect with all facts, but just as many facts as it takes for us to connect with what is deepest, truest, and highest. Fiducialists who do not seek out all facts are still receptive to them.
Fiducialism is disposed to value all things except to the extent that they betray. The process of growing in fiducialism sometimes requires betrayals, breakings-open. We can have a false wholeness that needs to be broken. Fiducialism wants us to be disposed to value all the things that matter, to have a complete picture. To the extent that we have the occasion or opportunity, we will value, connect with, all things.