  Adversarial vulnerability remains a major obstacle to constructing reliable
NLP systems. When imperceptible perturbations are added to raw input text, the
performance of a deep learning model may drop dramatically under attacks.
Recent work argues the adversarial vulnerability of the model is caused by the
non-robust features in supervised training. Thus in this paper, we tackle the
adversarial robustness challenge from the view of disentangled representation
learning, which is able to explicitly disentangle robust and non-robust
features in text. Specifically, inspired by the variation of information (VI)
in information theory, we derive a disentangled learning objective composed of
mutual information to represent both the semantic representativeness of latent
embeddings and differentiation of robust and non-robust features. On the basis
of this, we design a disentangled learning network to estimate these mutual
information. Experiments on text classification and entailment tasks show that
our method significantly outperforms the representative methods under
adversarial attacks, indicating that discarding non-robust features is critical
for improving adversarial robustness.
