在傳統認知論中，知識等於真實的信念加上合理相信的理由。在尋找合理的理由時，我們采用歸納法，從已經被肯定的知識中，推論相信新知識的合理理由。可是這裹有一個問題，若每一項知識也是從先前的知識推論出來，那層層遞進地推論追溯上去，那最初的知識如何肯定呢。傳統上基礎主義認為在知識的最底層，是一些不需論證自我肯定的基礎知識，作為所有知識推論的基礎。調和主羲則否定有基礎知識的存在，所有知論的推論是個巨大的循環，只能檢視整個知識系統的一至性，有沒有內部矛盾或對世界觀測的不協調。這篇功課討論調和主義理論本身的問題，探討調和主義能否成立。

The Coherence Theory of Empirical Knowledge

In this essay, I am evaluating Bonjour’s coherence theory of empirical knowledge (CTEK) against foundational theory of empirical knowledge (FTEK). First, I will outline what is the regress problem and compare the responses from FTEK and CTEK. Then I will examine the objection against CTEK regarding its relationship with external world. I will further extend the objection by arguing CTEK is asserting a fundamental assumption that the external world itself has to be coherent for CTEK to be justified. At last I am going to conclude CTEK is unsuccessful in overcome the objection in strictly epistemological sense but it is successful in practical sense.

Since Plato, traditional view of knowledge is justified true belief. A piece of belief is only qualified as knowledge if it is justified. A belief is justified based on the validity and soundness of its argument, which is implicitly depends on the premises used in the argument are also justified. Each premise on its own is also a piece of belief which required the justification of the premise’s premises. As a result, we have a regression of justifications for premises that keep tracing back, which is known as “the regression problem”. FTEK deals with the regression problem by stating there are some foundation beliefs at the very bottom of chains of premises and the regression terminates when the basic beliefs are reached. There are two version of FTEK. The strong version stated that the basic beliefs are self-justified without the need of further premises. The weak version stated that the basic beliefs are initially credible that are likely to be true. The CTEK rejects the notation of basic beliefs, instead of having the regression of premises go on infinite linearly, the inference is circular. An epistemic system is justified by its internal coherence.

However, the circular nature of CTEK runs into the problem of begging the question, which a belief cannot be justified unless it is already justified. The solution is to reject the linear conception of inferential justification and uses a holistic or systematic conception of inferential justification instead. CTEK separate the justification into two categories, justification of a particular belief and the global justification of the entire cognitive system. The justification of a particular belief appears linear, since the premises regression will soon reached some acceptable beliefs in the context. If no acceptable belief is reached, the premises regression will continue moving in a circle. In this case, the justification of the overall knowledge system comes under questions. In CTEK, the justification of the entire system is based on its degree of coherence. A coherent system must be internally consistence, which means there is no internal conflict, but it has more than just consistency. Coherent is the systemic connection between the components of the system, how observable facts can be explained and predicted. The justified knowledge system is the one with the highest degree of coherences out of all the alternative consistence systems.

In the paper, Bonjour lists three objections to CTEK on questioning the fundamental questions of the connection between coherence and justification. Out of the three objections, Bonjour spends most of the paper in defending against objection number two, the relationship of CTEK and external world. I think this is the strongest objection against CTEK and I also think Bonjour successfully defends CTEK against this objection. However, Bonjour omitted an underlining assumption in his defence that the external world has to be coherent in order to justify his argument. In the following paragraphs, I will first out the objection, go over Bonjour’s response to the objection and illustrate his hidden assumption with a counter example.

The strongest objection to CTEK is that since CTEK is justified only in terms the internal coherence of the beliefs in the system, it does not have any relationship with the external world. A self-enclosed system of beliefs cannot constitute empirical knowledge. Bonjour’s defense is pretty straight forward, it simply link the coherent belief system in CTEK to observable facts from external world. He argues that in CTEK, the coherent system of beliefs must also coherent with reliable observation of the external world in long run. When a particular observation does not coherent with the belief system, CTEK can either neglect the particular observation as an incoherent exception to the belief system or refine the belief system to include the new observation. If there are too many incoherent exception observations accumulated in the belief system, the belief system will become less coherent with the world and eventually it will be replaced by a more coherent belief system. The belief system is continuously updating itself upon new observation to maintain its degree of coherence. The input from external world has causal relationship with the CTEK belief system where the belief system is justified by its coherence with observable facts of the external world. One of the key pieces in Bonjour’s argument is to establish what can be constituted as reliable observations yet at the same time is not a basic belief. He argues that spontaneous introspective beliefs on spontaneous sensa beliefs are very likely to be true. The reliability of cognitively spontaneous beliefs is part of the coherence system along with the observation of the external world. Therefore it is not a prior truth in the sense that it is required as the foundation for justification of the knowledge.

Bonjour based CTEK’s justification on the coherence of the belief system and the reliable observation of external world in long run. Let’s granted that the belief system and the observations are reliable, however Bonjour failed to address the underlining assumption that the external world is coherence in long run. If the external world is not coherence, then no belief system can stay coherent due to CTEK has a causal relationship with the external world. Bonjour uses the spontaneous visual belief a red book and the lack of spontaneous visual of a blue book to illustrate how the belief system is linked to the external world. What if there is a chance that the book randomly change colour every time I observe it? How can I conclude there is a red book on my desk but not a blue book on my desk? Even though I can trust my spontaneous beliefs from my sensa of the book, I cannot trust the object under my observation stays the same between my two observations. It is possible that the cover of the book is made of the latest colour changing e-paper technology, which in the case we can provide a coherent account for the observable fact. However, it is also possible that there is no scientific theory can possible explain why the book change its color. It could be the act of God and it is simply a miracle that the book changed from red to blue for no apparent reason. The CTEK justification adopt an objective clock work world view that rule out the existence of any supernatural power, such as an omnipotent God who defies all laws of physics.
In theory, we cannot epistemological justify the CTEK because we cannot epistemological justify the world is coherent. Hume argues that “Uniformity of Nature”, which is essentially the same as coherence of the world, cannot be justified, yet it is rational and non-optional for us to accept the habit of inductive inference. Practically, we can assume the world is coherent almost all of the time and take it as a weak foundation that it is probably initially true until shown otherwise. CTEK is actually a very weak FTEK in disguise; the base belief of CTEK is that the world is coherence to provide the foundation to build coherent belief systems.

However, it would be totally absurd to argue the world is not coherent. If the world is not coherent, then even FTEK is not possible to have any knowledge system. Just like FTEK cannot convince the ultimate skeptic, CTEK also fail to convince the ultimate skeptic that there is justification on any knowledge. Given the fact that assumption of the world is coherent must dialectically acceptable in the context of any knowledge theory to have any meaning, we can grant this assumption a priori status outside of any epistemic dialog. With this particular exception, I conclude that CTEK is successful in overcoming the objection regarding the relationship of coherent belief system and the external world.

Reference:
[1] Laurence Bonjour, The Coherence Theory of Empirical Knowledge, Philosophical Studies 30 (1976) p281-312