As I pointed out several times -- yes, down underneath it all, I can't prove this isn't all just a dream. I can't even prove reality exists.
That was fascinating to me when I was 18, and new to philosophy. Now I see that as a shallow attempt to avoid actual, difficult analysis of the world around us.
In any universe in which the law of cause and effect exists, as it does in this one, then things are knowable based upon observation.
A thing is what it is.
Causes have effects.
"Beneficial" effects are a "good" choice, "detrimental" effects are a "bad" choice.
This is knowable, and provable -- assuming cause and effect.
You could best describe me as a 'Secular Taoist'. A Taoist without all the mysticism.
The core principle I live by is the idea that reality is what it is. There's an old story of a student asking his teacher what the truth was, and the teacher slaps the student in the face and says, "That was the truth".
What is, is. It is our challenge to see the objective, real truth and make choices that are most beneficial to our long-term self-interest. This is hard, perhaps impossible in many cases and for many people. But, objectively, obviously, it is the only choice, and everyone plays by that rule.
Admit it or not.
It happens. Guess you can't be an objectivist, then. You'll get over it ;)
In any universe in which the law of cause and effect exists, as it does in this one...
I suppose it would be crass of me to point out that this assertion is also far from proven true, but you can see David Hume's ideas on causation if you like....
"Beneficial" effects are a "good" choice, "detrimental" effects are a "bad" choice.
This is knowable, and provable -- assuming cause and effect.
Well, you're really assuming quite bit more than causality, but you're right - that's a necessary assumption. Which, again, just goes to show that you're not really an objectivist if you're going to assume things like causality, but you knew that. If it's objectively knowable that causality exists, which objectivism says it is, then you shouldn't simply accept it on faith until it's been rationally proven, again according to objectivism. Dunno how you're supposed to actually get anything done that way, but it is what it is - you're definitely right about that...