Questionnaires are indispensable in social science research, yet they are vulnerable to the instability of human cognition and emotion. Respondents’ answers often depend on their transient mindset, emotional state, or situational context, which may not reflect their enduring beliefs or behaviours. This paper examines the problem of response bias arising from mindset-dependent answering and evaluates whether such biases undermine the validity of social science research. Drawing upon the works of Choi & Pak (2005), Bogner & Landrock (2016), and Bhattacherjee (2012), among others, it argues that while bias cannot be completely eradicated, it can be minimised through methodological rigour, triangulation, and reflexive interpretation. The study concludes that social sciences do not fail due to bias; rather, their strength lies in the reflexive awareness and transparent management of human variability in responses.