The simple chatbots of the previous decade used predefined rules to choose from a narrow set of decisions. More advanced AI agents work to evaluate different solution paths, assess performance and refine their approach over time. At the core of an agent is the reasoning module. This module determines how an agent reacts to its environment by weighing different factors, evaluating probabilities and applying logical rules or learned behaviors. Depending on the complexity of the AI, reasoning can be rule-based, probabilistic, heuristic-driven or powered by deep learning models. Two popular reasoning paradigms are ReAct (Reasoning and Action) and ReWOO (Reasoning WithOut Observation).
Various agent types approach reasoning differently. For example, goal-based agents decide by considering a predefined goal and selecting actions that lead to achieving that specific goal. These agents focus on whether an outcome is achieved, rather than optimizing for the best possible outcome. Whereas utility-based agents take decision-making one step further by evaluating not just whether a goal is met, but how optimal the outcome is, based on a utility function.
Simple, rule-based AI systems follow predefined logic, such as "if X happens, do Y." More advanced systems use Bayesian inference, reinforcement learning or neural networks to adapt dynamically to new situations. This module can also implement chain-of-thought reasoning and multistep problem-solving techniques, which are essential for AI applications such as automated financial analysis or legal contract review. The agent’s ability to effectively reason and make informed decisions determines an agent’s overall intelligence and reliability in handling complex tasks.