I was recently hired by a startup that's working on computer vision. Unfortunately, my boss doesn't trust me very much because I don't have a PHD in computer vision (he's a business guy, who has very little understanding of computer science, and doesn't quite understand that degrees in this field are next to worthless). Is there a way to combat this without having to spend another 4 years in school? Am I ever going to gain enough of his trust to actually be allowed to do some of the cool stuff or will I be stuck doing the boring stuff forever? Anyone have any advice for me?
There's almost certainly a lot more to your story than what you're telling us, nor would I dismiss a CS PhD as "worthless". Like most degrees these days, it depends on whether it comes from MIT or "Bob's Online Ph.D. Mill".
By anyway: If you want to prove that you can do cool things in computer vision, then do something cool in computer vision. Build a working application that does more than just import a bunch of libraries, that actually requires some real math. Find a way to show it to the brains at your workplace, and get their feedback. If they like it, show it to your manager.
Job experience is often worth more than a degree, if you can make the most of it -- and remember, just because you aren't valued at one company doesn't mean you won't be valued at some other company. Finding the right work environment for your own skill set is part of the challenge.
I don't think your boss cares whether you have PhD.
The company hired you which should indicate some level of trust in your ability. Early stage startup hires have to be vetted by both the hiring manager and a founder and at later stage startups managers have more autonomy. Either way though your manager should have a say in whether you are hired or not. I used to say very bluntly to my direct reports "If I did not believe you could do the work, I would not have hired you."
I was recently hired by a startup that's working on computer vision.
Given that you are a new hire, your manager might be more involved in asking you about your work product. You should feel confident in discussing your work with your manager.
[My boss is] a business guy, who has very little understanding of computer science, and doesn't quite understand that degrees in this field are next to worthless
You seem to dismiss your manager's ability to comprehend your work. He is your manager after all and being able to explain technical topics to non-technical people is an important skill to advancing in your technical career. I would try to talk to your boss, test what level of detail he is comfortable with and slowly gain his trust by producing good work.
I worked at a biotech where the basic ladder looked like:
Research associates: Bachelors-Masters
Associate scientists: Masters
I'll agree that for the most part, your insights are taken with less weight than someone with a Ph.D. by management, and in some cases by the Ph.D. scientists when it comes to domain knowledge. There's a reason for this, and it's mainly that the Ph.D.s are hired with the intent that they are experts in their domain. I'll even go as far as to say when you work with the Ph.D.s you're astounded by their breadth of knowledge.
So when I started I was pinned to cell culture: stuff I did in undergrad. It wasn't until I showed my enthusiasm and ability to the people with the Ph.D.s that they began requesting my help. Slowly, they're the ones that begin to trust your skill and open up a world of career development, in my opinion. I think for senior coworkers who have a lot of domain experience this is typically true. But, don't expect the CEO to suddenly treat you at the same level.
In essence, work your way in with the people doing the cool stuff to get exposure to the cool stuff. But I don't think this approach will work for everyone. You also have to be getting your job done so you don't get fired, but see if your manager will let you shadow or work with someone on that level.