I've noticed that in the U.S., universities commonly provide funding for PhD students in AI/ML fields, including scholarships, assistantships, and fee waivers.
In contrast, Master's students have fewer funded opportunities and often rely on loans or work-study programs.
Can someone explain the reasons behind this difference in funding structures?
Here are a few reasons:
One reason, not yet mentioned, is that large, state supported, universities in the US, have a mission to support the common good. An educated public is essential to that end, providing broadly educated citizens that can drive toward a better future, both economic and otherwise. But that is balanced by limited resources and pushback from taxpayers whose individual wishes don't always mesh well with the needs of the general public.
So, a bachelor's degree is seen as a start, well worth supporting, with further education funded otherwise. Even doctoral students are supported mostly with teaching assistantships, not scholarships, so that those students actually contribute to the undergraduate program in exchange for their funding. Most large bachelor's programs couldn't operate without the support of those TAs. When I was a doctoral student the overall math department had twice as many TAs as faculty members. The TAs were all doctoral students. So, the two, support for undergrad and support for doctoral "fit" together nicely. Without support the doctoral students wouldn't be there and without them the undergrad program couldn't function.
Masters programs are sort of caught in the middle. The students may not have time or experience to be TAs and the funds available are pushed to the lower levels with, hopefully, more impact, hoping that masters students are willing to self-fund for a couple of years in the hopes of higher salaries. This is probably short sighted, but competing interests are at play.
Also, note a subtle distinction. The states, and their universities don't "fund" doctoral students. They fund research and some of that funding flows to doctoral students who participate in it, often in essential ways. And they provide low wage teaching assistantships and (usually) free tuition to doctoral students, but those students have duties to perform in return for that funding. Again, the computation is that this system maximizes the return on expended funds and supports the common good. You can, of course, question the validity of that computation.
Sadly, we seem to be moving to a world with less support for education overall, not just higher education. My own education was richly funded, though I completed degrees in the early 1970's. Things started to go the wrong way (IMO) about then, when we landed on the moon, "winning" a wager against the Soviet Union. It was, I think, the "fallacy of the last move" that suggested that we won, once and for all, and that support for a highly educated public wasn't that important a goal anymore. I've noticed steady decline since. My grandson will have no such luck. It saddens me that universities are dropping such programs as history and philosophy in favor of (only) STEM, and my path was math. A narrow, technical, education isn't adequate to support our future in my view; either for the individual or for society as a whole.
The reason is the economics of masters and PhD programs. Both generate revenue for the university but in different ways.
Masters programs make revenue by charging masters students for an intensive 1-2 year sequence of courses. In return, the students get improved career prospects via their new knowledge and having "Masters in Data Science from Big Name University" on their resume. The university profits from the tuition dollars, hence why masters students get charged.
PhD programs don't directly generate revenue, but they provide skilled labor on the cheap via research and teaching.
I know that sounds cynical... but it's also true! When you strip away the flowery prose about the pursuit of knowledge, and just follow the money, this is what you find.
Why Do Most American Universities Offer Funded PhD Positions but Not Similar Opportunities for Master's Programs?
As a broad statement, I would say this question is false. This question is specific to programs.
Some humanities and social science programs offer unfunded or partially funded PhDs. In contrast, many natural resource programs offer funded MS programs.
To expand upon the other answer, look and see if programs are "professional" or "research" programs. Some observations I have seen comparing the two types of programs:
Also, sometime service department with heavy teaching loads will use masters students to teach and provide TAs. Depending upon the size of the graduate program, these TAs may be open to professional masters students.
Unlike other countries where it is typical and even necessary to obtain a masters degree before a PhD, that is not typically the case in the US. Undergraduates can apply directly for a PhD and begin after they've earned their undergraduate degree.
Academic institutions serve two somewhat separate purposes in the US as in many places: first, they serve to educate students. Second, they perform research to push forward the knowledge of all humanity. In the US, education of students past the high school level is a cost mostly (and increasingly so) paid for by the students themselves rather than the government, whereas government continues to support research.
These two features sets up a bit of a two-track system:
Masters degrees are an add-on to a bachelors degree (which ordinarily students pay for) that help the student make more money in an industry career. Students are expected to treat the degree as an investment in their future and pay off the cost through their future earnings.
PhD degrees are the apprenticeship start to an academic research career and serve the broader mission of furthering academic knowledge. PhD students often work as employees on research projects, as teaching assistants, and in other ways that support their education while they are earning the degree; direct scholarships (often called "fellowships") are relatively rare. While doing this work, they are paid far less than what a similarly educated professional would earn, so even if they do not pay tuition they are still paying a substantial opportunity cost at least for their earnings in the short term, and possibly for their lifetime.
Generally, it's more difficult to apply and be accepted to a PhD program, so if a university has jobs available that could fund either a PhD or a masters student, it's natural to fund the PhD student because they will be there longer, funding them today helps the university's academic research mission in the future, and because in some sense they're "better" than the masters student: bluntly, if the masters student was more qualified and interested in the university's research mission they should have applied for and been accepted to the PhD program.
In my view, the biggest problem with this system is what to do with people who are trying to collect more credentials to apply to PhD programs, especially people who were unable to do research as an undergraduate (even more so those who were unable to do so because of financial disadvantages that affected the type of institution they attended or their available hours to do student research versus work another job to support themselves or their family). A masters program might be a good stepping stone, but someone who completes a masters and then starts a PhD will be in debt for a long time (perhaps indefinitely) before their earnings have increased sufficiently to pay off the degree.
Why should someone pay for your short term excursion in academia? In MS you actually can’t accomplish anything. The goal of the universities is to run their research machine and for that they need PhD students.
