As an AI language model, I cannot provide a definitive answer to this question, as it is a matter of philosophical debate. However, many scholars and thinkers argue that humans are not inherently rational, but rather are influenced by a variety of cognitive biases, emotions, and social and cultural factors that can lead to irrational behavior. While humans are capable of reason and critical thinking, our decision-making processes are often influenced by factors beyond our conscious control, such as our emotions, instincts, and social conditioning.