The limits of knowledge Flashcards
Explain the difference between philosophical scepticism and normal incredulity
Normal incredulity is doubt about commonplace questions in everyday life. For example, if I were approached on the street by someone claiming to have a new ‘miracle’ medical product, I might have normal incredulity towards their claim. Philosophical scepticism goes beyond such ordinary doubt and extends to almost everything we think we know. Examples of this may be the brain in a vat scenario, where sceptics say we could not know if we were simply disembodied brains being fed electrical signals artificially
Explain the role of philosophical scepticism within epistemology
Philosophical scepticism can be a useful tool to consult after making epistemological claims as it typically questions the adequacy of the justification for that claim. This encourages the philosopher to seek new evidence, strengthen their argument or rule out weak claims
Explain the distinction between local and global scepticism
Local scepticism is doubt about a particular claim or particular area of knowledge, whereas global scepticism extends without limit. It undermines all possible knowledge claims. The difference between these two concepts can be illustrated with this example: local scepticism may lead you to ask ‘can I trust my eyes to know if that pencil is crooked?’, but global scepticism may lead you to ask ‘can I trust my reasoning to know that the glass, water and pencil exist at all?’.
Explain Descartes’ first wave of doubt
Descartes’ first wave of doubt is the argument from perceptual variation and illusion – in other words, Descartes’ is doubting whether or not his senses are reliable. He notes that he has been deceived by his senses, with things often appearing as they are not (for example, a pencil half-submerged in water appears to be crooked). He argues that the possibility of perceptual error is sufficient to lead him to doubt the whole of sense experience.
(Possible response – we are only able to tell that our senses are sometimes deceptive because on other occasions we take them to be accurate. For example, we can only tell that a pencil looks crooked in water because we trust our eyes when it is not in water)
(Possible counter-response – Descartes is not saying that all sense-based beliefs could be false, but that none are guaranteed to be true)
Explain Descartes’ second wave of doubt
Descartes’ second wave of doubt is the argument from dreaming, in which he argues that he has no way of being able to tell if he is awake or dreaming. When we dream, we can represent to ourselves mundane things, such as dreaming that I am looking at a piece of paper, which is an indistinguishable experience from actually looking at a piece of paper. There is no reliable way to tell whether I am awake or asleep.
(Possible response – there are reliable ways of distinguishing between perception and dreaming, such as the far greater coherence of perception)
(Possible counter-response – what Descartes means is that I cannot know from my perception now whether I am awake or asleep. We cannot rely on memories of perception and compare them with dreams because what if we are dreaming that we remember things?)
Explain Descartes’ third wave of doubt
Descartes’ third wave of doubt casts doubt on all knowledge, even knowledge of mathematical and logical truths. He questions whether God may have deceived him (which Descartes argues he would not do) and then introduces a further doubt; there could be an evil demon producing your experiences who wants to deceive you. If this were true, there would be no way of knowing because your experiences would be exactly the same. So, Descartes says that he cannot know that he is not being deceived by an evil demon.
(Possible criticism – empty hypothesis? Because the evil demon’s trickery is undetectable, then for all practical purposes it makes no difference)
(Possible counter-response – this response simply concedes to the claims of philosophical scepticism)
Explain Descartes’ own response to scepticism
Descartes’ intuition and deduction thesis claims to find a foundation for knowledge in rational intuition. He believes that even the evil demon hypothesis cannot make him doubt that he exists as a thinking thing due to his cogito. The cogito, according to Descartes, is indubitable as it can be known clearly and distinctly and whatever he perceives clearly and distinctly must be true. Furthermore, Descartes uses a priori arguments to ‘prove’ the existence of a God who would not allow him to believe what is false (including his belief in a material world).
Explain Locke’s response to scepticism
Locke provides two responses to the sceptical challenge. Firstly, perception, unlike imagination, is involuntary. This suggests that perception is caused by something external to my mind, namely a mind-independent external world. Secondly, my different perceptions (such as sight and sound) are coherent, suggesting that there is a common reality that causes both. Both of these arguments challenge scepticism by providing evidence of an external world.
Explain Russell’s response to scepticism
P1: Either:
A: the external world exists and causes my perceptions
B: an evil demon exists and causes my perceptions
P2: I cannot prove A or B definitively – they are hypotheses
P3: A is a better explanation of my experience than B
C: Mind independent objects exist and cause my perceptions
Explain Berkeley’s response to scepticism
Most scepticism derives from the gap between our perception and reality, which allows for dreams, errors or demons to be the cause of our perception. Berkeley’s idealism removes the gap between our perception and the object, so sceptical scenarios aren’t really possible. If physical objects are no more than they appear to be, as Berkeley claims, then there is no gap between perceiver and perceived, so issues like the ‘evil demon’ have no bearing
Explain the reliabilist response to scepticism
The reliabilist definition of knowledge says that knowledge is a true belief formed via a reliable cognitive process (one which produces a high proportion of true beliefs). In ‘brain in a vat’ scenarios, reliabilism argues that although I cannot tell whether or not I am a brain in a vat, this does not show that I do not have knowledge of the world. If I am in the normal world, then my beliefs about the physical world are produced by a reliable process, and so count as knowledge. I do not need to additionally justify or prove that I am not a brain in a vat. While I cannot necessarily know that I have knowledge, this doesn’t matter as I have it regardless of if I know about it.
