What are the challenges in making LLMs more explainable?

Making large language models (LLMs) more explainable is challenging due to their complexity, dynamic behavior, and the lack of clear standards for measuring success. These challenges stem from how LLMs process information, adapt to inputs, and the subjective nature of what counts as a “good” explanation. Let’s break down the key issues.

First, LLMs are built using massive neural networks with billions of parameters, making it difficult to trace how specific inputs lead to outputs. For example, a model might generate a plausible-sounding answer by combining patterns from training data, but pinpointing which parts of the model contributed to that decision is not straightforward. Techniques like attention visualization or saliency maps can highlight important tokens in the input, but they don’t fully explain the model’s reasoning process. Developers face a trade-off: simplifying the model for transparency risks reducing its capability, while keeping it complex obscures understanding. This is especially problematic in high-stakes domains like healthcare, where users need to trust why a model suggested a diagnosis.

Second, LLMs are highly context-sensitive, meaning small changes in input can lead to vastly different outputs. For instance, asking a model to explain its answer in one context might produce a coherent rationale, while rephrasing the question slightly could result in a contradictory or nonsensical explanation. This unpredictability makes it hard to create reliable methods for consistent explanations. Additionally, many LLMs are fine-tuned or updated over time, which can alter their behavior in ways that aren’t immediately obvious. A developer might implement a post-hoc explanation tool, only to find it breaks after a routine model update because internal mechanisms have shifted.

Finally, there’s no consensus on what constitutes a sufficient explanation. A technical user might want details about gradient flows or layer interactions, while an end-user might prefer plain-language summaries. Without standardized metrics or benchmarks, it’s difficult to evaluate whether an explanation method truly improves understanding. For example, a tool that generates feature importance scores for model decisions might be useful for debugging but fail to address ethical concerns about bias. Efforts like model cards or transparency reports aim to document model behavior, but these are often static and don’t adapt to specific use cases. Until the field agrees on evaluation criteria and tools, progress toward explainability will remain fragmented.