You've misconstrued what you're replying to. The statement was:
Science is designed to avoid belief in untrue things
You misconstrued it here:
If science is to avoid belief in untrue things, you can instantly complete science by not believing anything.
Analogously:
lessdazed wrote that umbrellas are designed to protect against rain.
You replied that if umbrellas are to protect against rain, then you can instantly complete an umbrella by moving to a place with low precipitation.
When lesswrong said that science is designed to avoid belief in untrue things, he was not saying that everything that is to avoid belief in untrue things is science. Any more than had he said that umbrellas are to protect against rain, he would be saying that anything that protects against rain is an umbrella.
Science should maximize expected value.
That is a "should" statement. However, what science is, is an is, not an ought. There are many reasons to be careful about not bridging the distinction. One is that you want to distinguish between mechanism, proximate function, and (ultimate) function. Even if the ultimate function of science is to maximize expected value, that does not tell us anything about the mechanism of science or its proximate function, through which it maximizes expected value. Science may, for example, serve the ultimate goal of maximizing expected value by helping avoid belief in untrue things.
If we look at the activity of a scientist, not everything they do is science. A scientist needs to eat breakfast, but eating breakfast is not science. A scientist needs to imagine possibilities, but imagining possibilities is not science. Artists do that as well without being scientists. What makes someone a scientist - and I'm simply restating what I've heard many times and seems plausible, not something I've put a lot of thought into recently - is that he tests these imagined possibilities, which in the context of science are called hypotheses. It's putting the hypotheses to the test, particularly to a systematic, rigorous test, that sets science apart from other activities. And this bit - the testing bit - the bit which is what (I have often heard) makes science science and not religion or art - is designed to avoid belief in untrue things.
You wrote that "what science is, is an is, not an ought." Could you please explain what science is? I only ask because different people have different ideas of what science is or should be, and I'm a little unclear what is being referred to here. Thanks.
I just heard a comment by Braddock of Lovesystems that was brilliant: All that your brain does when you ask it a question is hit "search" and return the first hit it finds. So be careful how you phrase your question.
Say you just arrived at work, and realized you once again left your security pass at home. You ask yourself, "Why do I keep forgetting my security pass?"
If you believe you are a rational agent, you might think that you pass that question to your brain, and it parses it into its constituent parts and builds a query like
X such that cause(X, forget(me, securityPass))
and queries its knowledge base using logical inference for causal explanations specifically relevant to you and your security pass.
But you are not rational, and your brain is lazy; and as soon as you phrase your question and pass it on to your subconscious, your brain just Googles itself with a query like
why people forget things
looks at the first few hits it comes across, maybe finds their most-general unifier, checks that it's a syntactically valid answer to the question, and responds with,
"Because you are a moron."
Your inner Google has provided a plausible answer to the question, and it sits back, satisfied that it's done its job.
If you instead ask your brain something more specific, such as, "What can I do to help me remember my security pass tomorrow?", thus requiring its answer to refer to you and actions to remember things and tomorrow, your brain may come up with something useful, such as, "Set up a reminder now that will notify you tomorrow morning by cell phone to bring your security pass."
So, try to be at least as careful when asking questions of your brain, as when asking them of Google.