When announcing Open-AI's latest release last month, Sam Altman said "GPT-5 is the first time that it really feels like talking to an expert in any topic, like a PhD-level expert." Before we discuss whether GPT-5 got there, what does "PhD-Level intelligence" even mean?
We could just dismiss the idea but I'd rather try to formulate a reasonable definition, which I would expect from a good PhD student. It's not about knowing stuff, which we can always look up, but the ability to talk and engage about current research. Here is my suggestion.
The ability to understand a (well-presented) research paper or talk in the field.
The word "field" has narrowed over time as knowledge has become more specialized, but since the claim is that GPT-5 is an expert over all fields, that doesn't matter. The word "understand" causes more problems, it is hard to define for humans let alone machines.
In many PhD programs, there's an oral exam where we have previously given the candidate a list of research papers and they are expected to answer questions about these papers. If we claim a LLM has "PhD-level" knowledge, I'd expect the LLM to pass this test.
Does GPT-5 get there? I did an experiment with two recent papers, one showing Dijkstra's algorithm was optimal and another showing Dijkstra is not optimal. I used the GPT 5 Thinking model and GPT 5 Pro on the last question about new directions. A little more technical answers than I would have liked but it would likely have passed the oral exam. A good PhD student may work harder to get a more intuitive idea of the paper in order to understand it, and later on extend it.
You could ask for far more--getting a PhD requires significant original research, and LLMs for the most part haven't gotten there (yet). I've not had luck getting any large-language model to make real progress on open questions and haven't seen many successful examples from other people trying to do the same.
So while large-language models might have PhD-level expertise they can't replace PhD students who actually do the research.