Unlocking LLM System 2 Thinking: Tactics for Complex Problem Solving

Discover tactics to boost complex problem-solving with large language models. Learn how prompt engineering and communicative agents help unlock LLM's System 2 reasoning abilities. Optimize performance for challenging tasks beyond basic language generation.

July 14, 2024


Unlock the power of your mind with this insightful exploration of System 1 and System 2 thinking. Discover how to leverage these cognitive modes to tackle complex problems and make more informed decisions. This blog post offers practical strategies to enhance your reasoning abilities and unlock the full potential of large language models.

The Limitations of System 1 Thinking in Large Language Models

Large language models like GPT-4 excel at system 1 thinking - the fast, intuitive, and automatic cognitive processes. However, they often struggle with system 2 thinking, which involves slower, more deliberate, and analytical reasoning. This limitation is evident in their inability to effectively solve complex problems that require breaking down the task into steps, exploring different options, and evaluating the solutions.

The key issue is that large language models primarily rely on pattern matching and statistical prediction, without the ability to truly understand the underlying concepts or reason through the problem-solving process. They can provide seemingly reasonable responses to simple questions, but when faced with more complex tasks, they often fail to recognize the nuances and make the necessary logical deductions.

This limitation is highlighted in the examples provided, where the college students and the large language model struggled to solve seemingly straightforward problems because they relied on their intuitive, system 1 thinking rather than engaging in the more effortful, system 2 thinking required to arrive at the correct solutions.

To address this limitation, researchers are exploring ways to imbue large language models with more robust reasoning capabilities, such as through the use of prompting techniques like chain of thought, self-consistency, and tree of thoughts. These approaches aim to guide the models to break down problems, consider multiple options, and evaluate the solutions more systematically.

Additionally, the development of communicative agent systems, where multiple agents collaborate to solve complex problems, offers a promising approach. By having agents with specialized roles (e.g., problem-solver, reviewer) engage in a feedback loop, the models can better simulate the type of deliberative thinking that humans employ when faced with challenging tasks.

As the field of large language models continues to evolve, the ability to seamlessly integrate system 2 thinking will be crucial for these models to truly excel at solving complex, real-world problems. The research and advancements in this area will be crucial in shaping the future of artificial intelligence and its practical applications.

Enforcing System 2 Thinking Through Prompt Engineering Strategies

There are several prompt engineering strategies that can be used to enforce system 2 thinking in large language models:

  1. Chain of Thought Prompting: This is a simple and common method that inserts a "Reasoning step-by-step" prompt before the model generates the output. This forces the model to break down the problem into smaller steps and think through them.

  2. Example-based Prompting: Instead of just providing the "Reasoning step-by-step" prompt, you can give the model a few short examples of how to approach the problem. This helps the model understand the type of step-by-step thinking required.

  3. Self-Consistency with Chain of Thought: This method gets the model to run the chain of thought process multiple times, review the answers, and vote on the most reasonable one. This explores a few different options before arriving at the final answer.

  4. Tree of Thought: This is one of the most advanced prompting tactics. It gets the model to come up with multiple ways to solve the problem, explore the different branches, and keep track of the explored paths. This significantly increases the number of options the model considers.

The key benefit of these prompt engineering strategies is that they force the large language model to engage in system 2 thinking, breaking down complex problems, exploring options, and providing more thoughtful and accurate responses. However, the implementation complexity increases from the simple chain of thought to the more advanced tree of thought approach.

Leveraging Communicative Agents for Complex Problem-Solving

While large language models like GPT-4 have made impressive progress, they still struggle with complex, multi-step reasoning tasks that require "system 2" thinking. To address this, we can leverage the power of communicative agents - a multi-agent setup where different agents collaborate to solve problems.

The key benefits of this approach are:

  1. Divide and Conquer: By assigning specific roles and responsibilities to different agents (e.g., a problem solver, a reviewer, a researcher), we can break down complex problems into more manageable sub-tasks.

  2. Reflective Thinking: The interaction between agents allows for a feedback loop, where the reviewer can identify flaws in the problem solver's approach and prompt them to re-evaluate and improve their solution.

  3. Exploration of Alternatives: Communicative agents can explore multiple solution paths in parallel, rather than being limited to a single, linear approach.

To implement this, we can use frameworks like AutoGPT, which make it easy to set up collaborative workflows between agents. This allows us to define the agents' roles, skills, and interaction patterns, and then observe the agents working together to solve complex problems.

For example, we can create a "Problem Solver" agent and a "Reviewer" agent to tackle the logic puzzle you described. The Problem Solver would first attempt to solve the puzzle, and the Reviewer would then analyze the solution, identify any flaws, and provide feedback to the Problem Solver. This iterative process would continue until the Reviewer is satisfied with the final answer.

By leveraging communicative agents, we can push the boundaries of what large language models are capable of, enabling them to tackle more complex, multi-step reasoning tasks that require "system 2" thinking. As the field of AI continues to evolve, I'm excited to see how these techniques can be further developed and applied to solve increasingly challenging problems.

A Practical Example: Solving a Challenging Logic Puzzle

In this section, we will walk through a practical example of using a multi-agent system to solve a complex logic puzzle that even GPT-4 struggles with.

The task is as follows:

There are four animals - a lion, a zebra, a giraffe, and an elephant. They are located in four different houses with different colors - red, blue, green, and yellow. The goal is to determine which animal is in which color house, based on the following clues:

  1. The lion is either in the first or the last house.
  2. The green house is immediately to the right of the red house.
  3. The zebra is in the third house.
  4. The green house is next to the blue house.
  5. The elephant is in the red house.

This problem is quite challenging, as it requires carefully considering each clue and deducing the final arrangement. Let's see how we can use a multi-agent system to solve this problem.

First, we set up two agents in the AutoGen Studio - a Problem Solver and a Reviewer. The Problem Solver's role is to try to solve the task, while the Reviewer's role is to critique the solution and provide feedback.

The Problem Solver generates an initial solution, which the Reviewer then evaluates. The Reviewer identifies flaws in the solution and provides feedback to the Problem Solver. The Problem Solver then revises the solution based on the Reviewer's feedback, and the process continues until the Reviewer is satisfied with the final answer.

Through this iterative process, the multi-agent system is able to explore different options, identify and correct mistakes, and ultimately arrive at the correct solution. This approach is much more effective than relying on a single model, as it allows for more thorough problem-solving and self-reflection.

The key benefit of this multi-agent setup is that it simulates the way humans solve complex problems, where we break down the problem, explore different options, and critically evaluate our own work. By implementing a similar process with AI agents, we can better leverage the strengths of large language models to tackle challenging tasks that require system-2 level thinking.


Large language models like GPT-4 have impressive capabilities, but they often struggle with complex, system-two level thinking tasks. To address this, researchers are exploring ways to enforce more deliberate, step-by-step reasoning in these models.

One approach is through prompt engineering techniques like "chain of thought" prompts, which break down problems into smaller steps. More advanced methods like "self-consistency" and "tree of thoughts" further explore multiple solution paths.

Another promising direction is the use of "communicative agents" - setups where multiple AI agents collaborate to solve problems, with one agent acting as a reviewer to identify flaws in the other's reasoning. Tools like AutoGPT make it relatively easy to set up these multi-agent systems.

Ultimately, the goal is to develop large language models that can adaptively switch between fast, intuitive "system one" thinking and slower, more deliberate "system two" reasoning as needed to tackle complex challenges. While current techniques show promise, there is still much work to be done to achieve this level of sophisticated, flexible intelligence in AI systems.