Towards System 2 Reasoning in LLMs: Learning How to Think With Meta Chain-of-Though

We propose a novel framework, Meta Chain-of-Thought (Meta-CoT), which extends traditional Chain-of-Thought (CoT) by explicitly modeling the underlying reasoning required to arrive at a particular CoT. We present empirical evidence from state-of-the-art models exhibiting behaviors consistent with in-context search, and explore methods for producing Meta-CoT via process supervision, synthetic data generation, and search algorithms. Finally, we outline a concrete pipeline for training a model to produce Meta-CoTs, incorporating instruction tuning with linearized search traces and reinforcement learning post-training. Finally, we discuss open research questions, including scaling laws, verifier roles, and the potential for discovering novel reasoning algorithms. This work provides a theoretical and practical roadmap to enable Meta-CoT in LLMs, paving the way for more powerful and human-like reasoning in artificial intelligence.

Host: Hey everyone, and welcome back to the podcast! I'm your host, Leo, and I'm super excited for today's discussion. We're going to be diving into something a little different, a little nerdy, but incredibly important for the progress of science and knowledge in general. We'll be talking about the arXiv e-print repository.

Guest: Hey Leo, and hey everyone! Yeah, arXiv is one of those things that's absolutely foundational but doesn't always get the spotlight. Most people, outside of the academic and research circles at least, don't really think about where scientific knowledge is first shared before hitting formal publications. I'm glad we're shining a light on it today.

Host: Exactly! I think it's so important for people to understand the infrastructure that supports scientific discovery. It's not just like magic where papers suddenly appear in journals, right? There's this whole pre-publication ecosystem, and arXiv is a huge part of it. So, for those who might not be familiar, what exactly is arXiv? I know it's not a typical journal.

Guest: That's a great question to start with. Yeah, arXiv isn't a journal, it's essentially a digital archive, a giant repository of pre-prints. Basically, scientists often want to get their findings out there quickly, long before the peer-review process is complete, which can take months, or even years. So, they submit their papers to arXiv, making them freely and publicly available. It's like a public announcement of their research, it gives priority, and allows other researchers to build on it quickly.

Host: Okay, so it's like a fast track for research dissemination. I see the value in that, especially in fields where rapid progress is crucial. But, does this mean that anything can just go on arXiv? Is there a vetting process at all? Because, you know, the term 'pre-print' does make it seem a little 'wild west,' like anything goes.

Guest: That's a really valid concern. It's not completely 'anything goes,' though it's less formal than a journal. There’s a layer of automated checks and minimal human review mostly focused on formatting and relevance. The primary purpose of arXiv is not to filter for scientific rigor. It's more about distributing research fast. There are moderators, but it’s not a full-blown peer review system like you find with journals. They're mainly there to catch things that are clearly not scientific content or are in some other way inappropriate or in the wrong categories.

Host: That makes sense. It's more about making the work accessible quickly, and then the rigorous review happens later in the publication process. But it seems like there could be potential for, like, errors, even completely false claims going up, since it’s pre-peer review. How does the community approach this? Is there an understanding that the science on arXiv should be taken with a grain of salt, so to speak?

Guest: That's absolutely correct. There's a general understanding within the research community that papers on arXiv are pre-prints, not the final version. They should be considered works in progress. You definitely can't treat everything on arXiv as gospel. Researchers usually approach it with critical thinking and awareness that the work hasn't gone through formal review. It's about staying current on the field but not just blindly accepting everything at face value. This is also why researchers usually cite the official journal publication when the paper has completed its review. It's not uncommon for papers on arXiv to later be revised significantly in peer review before being officially published.

Host: So, it's a delicate balance then, between speed and rigor. You get the quick dissemination of ideas, but you also have to maintain a critical eye on the research. I guess that also places an extra burden on researchers to be careful about the quality of what they’re putting up. I imagine this whole process must be really important for new discoveries, and to get credit for those discoveries.

Guest: Precisely. The speed is a critical factor, especially in fast-moving fields like, say, artificial intelligence or particle physics. For the point of discovery, putting the work on arXiv establishes priority. This means you can demonstrate you were first with a given idea. Also, it gives other researchers in the field a chance to see it and comment on it, potentially improving the research even before the formal peer-review starts. There are examples where, after a pre-print was posted, other researchers flagged significant errors and saved a lot of time for the initial authors.

Host: That’s a fascinating dynamic! It's like an informal community peer review happening alongside the more formal process. I guess it also promotes a level of transparency, as everyone in the field can see what others are working on, which could lead to even more collaborative efforts.

Guest: That's absolutely right. The transparency is a huge benefit. It really opens up the black box of the research process a bit. You're not just waiting for a published journal article to come out, you see the process a bit, and can see what others are currently working on. This also enables a kind of collaborative competition. Research is not just done in isolated groups. Researchers often build on the work of others, and the arXiv speeds up this process, accelerating scientific progress.

Host: So, in a way, arXiv fosters more of an open-source approach to research? Rather than keeping things secret until publication. It seems like it also levels the playing field a bit, as even researchers who are not part of big institutions have a platform to share their work and gain visibility.

Guest: Yes, exactly! It promotes a more open and democratic approach to knowledge. Researchers from smaller universities or less well-funded institutions can gain just as much visibility as those from major research hubs. This aspect of it is crucial for diverse voices in the field to be heard. And, you're right, it's like an open-source approach where the aim is to collectively make progress as a community. The speed of dissemination means that no one institution has the information and the advantage. It makes sure that the science goes faster.

Host: It's interesting to think about this massive archive, constantly being updated. I saw on the website, which we'll link in the show notes, that they are supported by the Simons Foundation and member institutions, and that people can also donate. It's such a critical piece of infrastructure for science, it’s great to know there's a collective effort to maintain it.

Guest: It really is. It's an impressive example of a community-driven resource. The fact that arXiv is not-for-profit and operates on this model is so important. It means that access is free to anyone in the world, regardless of their financial situation or affiliation. It bypasses expensive paywalls that are often associated with journals. This allows researchers all over the world to keep up to date on the field, and allows the public to see the progress as it is happening.

Host: That makes the whole system far more equitable, and allows people from all over the world to benefit from scientific progress. Also, I noticed that they have support for HTML conversions, and they mention some difficulties with certain formats of files. It seems like they put an emphasis on making the information as accessible as possible.

Guest: Exactly! The HTML conversion is a crucial part of their efforts to make the content as accessible as possible to everyone, including those with disabilities. They're constantly working on making the archive more user-friendly. If the original paper is submitted as LaTeX, for example, it needs to be converted to other formats for easy viewing. While most papers are in PDF format, the move to HTML is crucial for long-term access and accessibility. It is one of the areas they continually work on, as you mentioned. This also helps with search and indexing, which is vital for such a huge repository.

Host: And thinking about the sheer volume of papers on there, the search function must be pretty critical. I noticed there's an option for 'Advanced Search' too, which I'm sure researchers are utilizing constantly. Otherwise, it would be a huge information overload.

Guest: Oh, absolutely. The advanced search is a lifesaver. With the rate at which research is published, being able to narrow down the search with specific keywords, author names, subject areas, or even date ranges, is absolutely vital. You would be completely lost without that. The system is constantly being updated with new research, so refining the search parameters is critical to staying on top of it all. Otherwise the scale of it would be completely overwhelming.

Host: It’s really like a constantly growing library of cutting-edge research. I wonder, is there a lot of overlap between what goes on arXiv and then what eventually gets formally published? Like, do most of the papers there eventually make their way to peer-reviewed journals? Or is there a portion that just lives on arXiv permanently?

Guest: That’s a really insightful question. There's definitely a lot of overlap, but it's not a one-to-one relationship. The vast majority of papers on arXiv are eventually submitted to peer-reviewed journals, and after going through the peer review process, will be officially published. However, some papers might just stay on arXiv, and this often happens for a few reasons. Sometimes, research findings are preliminary and might not be fully fleshed out, or the researchers might decide to work on something else before going through formal publication. Also, some work is published in the proceedings of conferences, but might not also get a formal journal publication, in which case the pre-print version on arXiv remains the definitive record. And there are also cases where the authors decide for whatever reason not to pursue publication in a journal, and are happy for the work to just reside on arXiv. The arXiv version is still considered the authoritative and quotable source.