  The recent growth in the popularity and success of deep learning models on
NLP classification tasks has accompanied the need for generating some form of
natural language explanation of the predicted labels. Such generated natural
language (NL) explanations are expected to be faithful, i.e., they should
correlate well with the model's internal decision making. In this work, we
focus on the task of natural language inference (NLI) and address the following
question: can we build NLI systems which produce labels with high accuracy,
while also generating faithful explanations of its decisions? We propose
Natural-language Inference over Label-specific Explanations (NILE), a novel NLI
method which utilizes auto-generated label-specific NL explanations to produce
labels along with its faithful explanation. We demonstrate NILE's effectiveness
over previously reported methods through automated and human evaluation of the
produced labels and explanations. Our evaluation of NILE also supports the
claim that accurate systems capable of providing testable explanations of their
decisions can be designed. We discuss the faithfulness of NILE's explanations
in terms of sensitivity of the decisions to the corresponding explanations. We
argue that explicit evaluation of faithfulness, in addition to label and
explanation accuracy, is an important step in evaluating model's explanations.
Further, we demonstrate that task-specific probes are necessary to establish
such sensitivity.
