意識的問題又可稱之為心之不可化約性問題，這個問題簡單的說就是「我們無法使用物理或科學概念來解釋意識」，另一個說法就是「心靈概念無法被物理概念所化約」。在這個問題的說明上，耐格提出著名的蝙蝠論證指出，無論我們對蝙蝠的大腦有多瞭解，我們都不可能知道作為一個蝙蝠的感覺是什麼。另外，在分析這個問題方面，耐格指出，此問題的根源在於第一人稱的觀點與第三人稱的觀點之間無法溝通。而針對這個問題的解決方向上，耐格提出擴展論，主張我們目前對心靈與物質的瞭解都是正確的但卻是不足的，我們必須增加對心物的瞭解，進而發現它們之間的必然關聯，然後藉由這個必然關聯的發現，發展出新的概念或概念框架來解決這個問題。本文將針對耐格對意識問題的觀點深入分析與討論。

The problem of consciousness is also called the problem of the irreducibility of the mind, which means that we encounter a problem when
we try to use physical concepts to explain consciousness. In other words,
mental concepts are not reducible to physical concepts. For explaining this problem, Nagel argues that no matter how much we understand a bat’s
brain, it is impossible for us to know what it is like to be a bat.
In addition, Nagel argues that the problem is generated by the inconsistence between the first-person point of view and the third-person
point of view. Mental concepts are understood through the first-person point of view and physical concepts are understood through the third-person point of view. These points of views form two different conceptual frameworks which cannot completely communicate with each other.In order to find a way to solve the problem of consciousness, Nagel presents expansionism, which suggests that, our understanding of the mental
and the physical is basically correct, but not complete. We have to improve our understanding by finding the necessary connection between the metal and the physical. According to the connection, we will produce a new
conceptual framework to solve this problem. In this paper, I will analyze
and discuss these views.