In this paper, I propose to do four things. Firstly, I will give a quick explanation of scepticism in a short paragraph in order to allow the reader to have some understanding of what scepticism is. This will be a general outline of the main premises and conclusions that a sceptic would give in response to knowledge about the external world. Secondly, one form of scepticism will be introduced, in this case Humean scepticism, and following from that, appropriate common-sense objections. This will begin the argument of this paper which is that the best response to scepticism is the common-sense theory. Thirdly, I will give a detailed dialectic account of the common-sense argument put forward by G.E. Moore, with relevant objections from a sceptic. The main focus of this discussion will be Moore’s hand example which is his “proof” of an external world, found in Proof of an External World. Lastly, objections and defences to the common-sense theory will be discussed as a way of further arguing against scepticism. By finalising this essay, the conclusion will be a summary including that scepticism fails and that the best response to this failure is the common-sense theory.
In order to comprehend this paper and to understand how scepticism, as an argument for the external world, fails, stating the general principles of scepticism is a necessity. It is argued that we should try to believe things when there are good or sufficient ground for their truth. This is the Epistemic Ideal 1. Furthermore, we should try to avoid believing things when there are insufficient grounds, or no grounds at all, which is the Epistemic Ideal 2; Non-belief in Falsehoods. Taken to the extreme, this can lead to the vice of scepticism. A sceptic would generally argue that we shouldn’t believe things because our grounds aren’t sufficient. According to this, we practically fail to satisfy the Epistemic Ideal 2. There are different varieties of scepticism, and despite only discussing one of those forms in this paper, each variety shares the denial of an epistemic attitude towards something. For example, a sceptic regarding knowledge has the denial of knowledge and warrant.
Humean Scepticism, established by David Hume, targets the knowledge of the unobserved and has the main thesis that we know a lot less than we ordinarily take ourselves to. The question that this type if sceptic would raise is, how do we know ‘things’ about ‘stuff’ that we haven’t yet observed? For example, how do you know that a man named Napoleon conquered much of Europe, without ever meeting him and observing him in action? Hume distinguishes between relations of ideas and matters of fact. Relations of ideas are something whose denial is inconceivable or self-contradictory. Such as, you know that a triangle has three sides and to imagine it having two is simply inconceivable. Propositions of this kind have to be true and are discovered by mere operations of thought and nothing else. Matters of fact claims, on the other hand, may be true but are not inconceivable or self-contradictory. The mere operation of thought is not enough to get us complete knowledge of their truth. You have to go out and gain empirical evidence in order to gain this knowledge. However, this form of scepticism notices that our empirical warrants depend on us having collateral assumptions, such as our sense organs aren’t deceiving us. It then notices that there are no evidential grounds to support those assumptions. Concluding that at the bottom of all out practices are ungrounded assumptions that cannot be rationally held.
A common-sense philosopher would renounce this as nonsensical. Many have argued, like Descartes, that we have reason to doubt our senses. However, there are many reasons why our senses could have been deceived and those reasons don’t lead to scepticism and the fact that we don’t know anything. For example, further observations have made it clear that a given object wasn’t the colour it first appeared to be, but through this further observation you found the true colour. Another reason why our senses could have deceived us is through testimony. Testimony is the process of communication with others, such as speaking and writing. Reid notes that ‘in the matter of testimony, the balance of human judgement is by nature inclined to the side of belief; and turns to that side on itself, when there is nothing to put into the opposite scale’ (Inquiry Into the Human Mind VI.24). Essentially, Reid is arguing from the principle of credulity, that if you are told something and you have no reason to disbelieve it, you should believe it. Therefore, unless you have good reason to disbelieve your senses, you should never doubt them and then take what they give you as truths about knowledge. It would be nonsensical, albeit in a non-sematic sense, to doubt our senses as it goes against our notion of epistemic rationality.
In Proof of the External World, G.E. Moore begins by criticising Kant. Before discussing Moore, I will give a quick account of Kant’s proof of the external world. In Critique of Pure Reason, Kant states that “the mere, but empirically determined, consciousness of my own existence proves the existence of objects in space outside me” (Kant, 1998). Kant is essentially arguing that you perceive your own self and your own consciousness as existing through time and the only way you can do this is in reference to persistent, real objects which exist outside of you. Moore claims that Kant wasn’t able to give a successful proof of the existence of things outside of us. He asserts that x doesn’t entail y, despite y entailing x. For example, ‘things which can be met in space’ entails ‘things presented in space’ but not the other way around since there may be things that are presented in space that cannot be met. However, Moore thinks that by giving a proof of the existence of physical objects then he will be able to prove that there are things which can be met in space which are external to us. As a critique of Moore’s view, many have stated that his view is highly problematic. For example, he claims that we cannot perceive an animal’s pain, but this doesn’t follow from us regarding them as physical objects intuitively. To counter this, it would be said that a physical object is everything that we could perceive which exists independently of the fact that we actually perceive. Moore gives the example of a hand to strengthen his proof of the external world, and this is the main focus of my account on Moore. He arguments goes as 1) here is a hand, 2) here is another hand, so 3) there are at present two human hands. 3) entails that 4) there are physical objects, so has proved that 5) there is an external world. Whilst this is a valid point, some have argued that this isn’t a response to scepticism and is actually a response to idealism. Moore has responded to this critique my agreeing that his proof was directed to an idealist but in spite of this, if it is true that Moore knew that there were two hands, it them must follow that he knew there was/is an external world. This is clearly anti-sceptic. This then raises the question of how does Moore know that the premises are true? This question can be answered by Moore and the common-sense theory. It doesn’t matter how much a sceptic can press you to give a justification for your claims to knowledge. A philosopher of common sense would distinguish between knowledge and the conditions to which it had been obtained and then what he sees as the challenge raised by the sceptic; which would be the challenge of proving. “I can know things, which I cannot prove; and among things which I certainly did know, even if (as I think) I could not prove them, were the premises of my … [proof]” (Moore, 1962).
Before concluding this paper, I will discuss the two main problems that the common-sense theory needs to tackle in order to be a sound and reasonable approach to take, especially in response to scepticism. The first problem that it faces is that scepticism fails to give a non-circular argument for the reliability of memory and perception. Secondly, they pick out instances of knowledge without a criterion of knowledge. This links to Chisholm’s and his problem of the criterion which follows that to know whether things are as they seem to be, we must have a procedure for distinguishing appearances that are true from appearances that are false. However, to know that a procedure succeeds, we need to know whether it is successful in distinguishing true and false appearances; but we don’t know which appearances are true or false due to the first point made. Despite this, neither of these objections provide good reasons for rejecting the basic approach of the common-sense theory. To address the first objection, many common-sense philosophers argue that knowledge does not require a non-circular argument to determine whether our cognitive faculties are reliable. Furthermore, we can achieve reflective knowledge of our own reliability by considering track-record arguments; arguments where we gain a sample of beliefs that are based on sense perception and take the proportion of truths in this sample as an estimation of the reliability we can hold over those sources of beliefs. When addressing the second objection, we need to look back and defend Chisholm and his idea of particularism. This is the position that we correctly start with things we know and through them, we develop the justification for this knowledge. The issue with particularism is that it determines that we already have knowledge, but many people disagree, such as a Methodist, by stating that we don’t have a procedure to determine the difference between truths and knowledge which is false. A response to this would be to consider those Particularists who also think that our knowledge of epistemic principles is a priori. An argument against this response would address the issue that if this is the case, then our knowledge is certain and indefeasible causing our intuitions to fail in determining which knowledge is true or false. However, to counter this, philosopher Noah Lemos creates the solution that we should take a “modest” view of a priori knowledge, holding that this type of knowledge can be defeated by other considerations and can also be less than certain (Lemos, 2004).
To conclude, we have discussed scepticism in general before moving on to consider one variety of scepticism in order to critique it more specifically. Such as, that scepticism fails to rely on our senses despite there being multiple examples, the majority being included in this essay, to determine that we have no reason to doubt them with regards to the external world. Then the dialectic account of G.E. Moore’s common-sense theory was introduced, finalising that it is a sound argument to take. And lastly, defences to the two main objections were put forward to fully conclude that the common-sense theory is a coherent and appropriate response to scepticism and the external world.