Anytime Generation of Counterfactual Explanations for Text Classification

In many machine learning applications, it is important for the user to understand the reasoning behind the recommendation or prediction of the classifiers. The learned models, however, are often too complicated to be understood by a human. Research from the social sciences indicates that humans prefer counterfactual explanations over alternatives. In this paper, we present a general framework for generating counterfactual explanations in the textual domain. Our framework is model-agnostic, representation-agnostic, domain-agnostic, and anytime. We model the task as a search problem in a space where the initial state is the classified text, and the goal state is a text in the complementary class. The operators transform a text by replacing parts of it. Our framework includes domain-independent operators, but can also exploit domain-specific knowledge through specialized operators. The search algorithm attempts to find a text from the complementary class with minimal word-level Levenshtein distance from the original classified object.