So let's talk about our preference assumptions.
So, to model consumers' preferences across goods,
we're going to impose three preference assumptions.
Three preference assumptions.
The first assumption is completeness.
The first assumption is 
the assumption of completeness.
When comparing two bundles of goods,
you prefer one or the other.
You can't say, I'm not sure.
You can't say, I'm not sure.
You can't say, I'm not sure, you can't say 
I don't know, I don't know how I feel about that.
The second is transitivity.
Which is something we've been learning since
kindergarten about transitivity, right?
And also, it's a different context.
That's just if you prefer x to y, and y to
z, you've got to prefer x to z.
OK, you guys should do transitivity 
in your sleep by now.
OK, so the standard transitivity 
we always assume in math class,
we're going to assume here as well.
OK, that should be pretty noncontroversial.
OK, and then finally, 
and probably most controversial,
is we're going to assume non-satiation.
Or the famous economic assumption 
that more is always better.
More is always better, that is, 
you never would turn down having more.
