rationale 是reason的书面典雅表达，在论文写作中可以替代reason，体现作者的英语修养。
例如：
The rationale (reason) why deep learning is of layered structure is that inspired by the significant discovery of layered structure of animals’ vision neural systems, scientists created artificial vision neural networks using layered structure, and other artificial neural networks could be considered as extensions of artificial vision neural networks. Interestingly, layered artificial neural networks i.e. deep learning achieve great success in image identification and natural language processing. Note that structure of natural neural networks other than visual neural networks remains unknown for the time being.（为什么深度学习具有层次结构的理由是：受动物视觉神经系统层次结构这一重大发现的启发，科学家使用层次结构建立人工视觉神经网络，而其他人工神经网络可以认为是人工视觉神经网络的扩展。有趣的是，层次人工神经网络（深度学习）在图像识别和自然语言处理方面取得巨大成功。需要注意的是目前除视觉神经网络之外，其他自然神经网络的结构仍然不明了。）
（例句原创）