I have no formal education in logic. I'm confused by the phrasing "may be the state of."
When I hear, "the state of" I think of a condition, a temporary status. I work it out like so...
"Depressed" may be the state of "Jessica" (because she's been listening to sad music.)
What "Brian, Jessica's boyfriend" does (go out drinking with his buddies because his girlfriend is questioning their relationship. Again.) is determined by the state of "Jessica."
Therefore, for all we know, what Brian does may be determined by Depression.
I voted Yes, but I may have to change to "I don't know."
I think the doubts you express here come from the fact that your own example is slightly off, which is straight away signalled by your use of the quotes around "Depressed".
So, first, the statement "
A may be the state of B" should be understood as exactly what it says. So, if A is indeed the state B, then A is nothing but the state of B. However, your "Depression" here is more readily understood as the name of a medical condition that effectively affects millions of people. As such, "Depression" is not understood as the state of Jessica and thus, the idea that what Brian does is determined by "Depression" seems to say that what Brian does is determined by depression as the medical condition affecting millions of people, which seems wrong.
Second, the word "Jessica" is normally understood as referring to a person and while we think it may be true to say that a person is in a state of depression, we don't usually think it is true to say that depression is the state of a person. So, your premise probably sounds false even to you. Here again, for the premise "
A may be the state of B" to be accepted as true, we need to be able to think of A as being the state of B and not the state of something else. Depression is not understood as the state of a person. but as a state the person may be in.
So, it's not depression, understood as the medical condition of millions of people, but Jessica's depression, which is relevant here. And it's not Jessica's state, but the state Jessica is in.
Reworded accordingly, the argument should immediately sound much less doubtful to you, and I hope obviously valid:
Jessica's depression may be the state Jessica is in
What Brian does is determined by the state Jessica is in
Therefore, What Brian does is determined by Jessica's depression
That's obviously a different argument, but part of the logical structure is the same and should help you accept the original argument.
Thank you to say whether this helps or not.
EB