You've misinterpreted what is meant by "complexity of value". It does not mean that human utility is multidimensional. It means that the human utility function is very complex.
Specific example:
[freedom, happyness, love, beauty, fun] (that's supposed to be a vector) is not a utility function and cannot be used for decision theory.
Something like (freedom + happyness + love + beauty + fun) or minimum-of(freedom, happyness, love, beauty, fun) is a (somewhat complex) utility function.
Having a complex utility function doesn't make torture vs dust specks solve differently.
Don't use the word if the guy just got confused by the word :D
Value is (complex) complicated.
Reasoning using a representation of human utility that's a simple continuum from pain to pleasure, as torture vs dust specks does, is a shattering blow to the complexity of value.
Making moral decisions of such vast scope without understanding the full multidimensionality of human experience and utility is completely irresponsible. An AI using the kind of reasoning found in Torture vs Specks would probably just wirehead everyone for huge-integer-pleasure for eternity.
I don't pretend to know the correct answer to Torture vs Specks because I don't have a full understanding of human value, and because I don't understand how to do calculations with hypercomplex numbers. A friendly AI *has* to take into account the full complexity of our value and not just a one-dimensional continuum whenever it makes any moral decision. So only a friendly AI which has correctly extrapolated our values can know to high confidence the best answer to torture vs specks.
(edit 1) re:Oscar Cunningham
Why does complexity of value apply here specifically and not a curiosity stopper? Well consequentialist problems come in different difficulty levels - Torture for 5 years vs Torture for 50 years is easy - torture is bad, so less torture is less bad. You are comparing amounts of the same thing. You don't have to understand complexity of value to do that. To compare the value of two very different things, like Torture and Specks, requires you to understand the complexity of value. You can't simplify experiences to integers, because complex value isn't simply an integer.
The intuition that torture must be outweighed by a large enough number of specks, is just that: an intuition. You don't know the dynamics involved in a formal comparison based on a technical understanding of complex value.