Limits Of Knowledge: Scepticism Flashcards
Outline and explain scepticism
- Scepticism is the view that our beliefs amount to knowledge are inadequate, so we do not in fact have knowledge.
- Scepticism can target knowledge from any source, including perception and reason, so if challenges both empiricism and rationalism.
Outline and explain how philosophical scepticism is fundamentally different from normal incredulity.
-The thought experiment of ‘a brain in a vat’ shows how it doesn’t make sense to be sceptical in everyday circumstances. It leads us to question everything including memories, perception, senses etc.
-What are the 2 types of scepticism?
- Local Scepticism: Is Scepticism about some specific claim, or more commonly, about some area/branch of supposed knowledge. E.g. debating how many planets exist.
- Global Scepticism: Extends doubt without limit. The brain in a vat provides an example. It has focused especially on having no knowledge of an external world or physical objects.
Why does Descartes create his three waves of doubt?
- He does this as he is seeking to work out what we can know to be true, so this is ‘completely certain and indubitable’.
- He adopts scepticism at the start of this so he can doubt his beliefs and establish certainty if the pass the doubt.
- If doubted each belief in turn (local) this would take forever. So he decides to question the principles on which his beliefs are based. We can understand this as his calling into question the general justifications we offer for our beliefs (global).
What is the first wave of doubt (Illusion)?
-Against his sense experience as we can be deceived by our sense e.g. crooked pencil. However, Descartes remarks that such examples from unusual perceptual conditions give us no reason to doubt all perceptions.
- More generally, we might say that perceptual illusions are special cases (and ones we can frequently explain).
- Otherwise we wouldn’t be able to talk about them as illusions. So they don’t undermine perception generally.
Outline and explain Descartes waves of doubt (dreaming).
- Descartes then doubts whether we can know he is awake. There is no reliable way to tell whether I’m awake or asleep.
- Descartes claims that dreams are constructed out of basic ideas and these must correspond to something real- ideas of body, extension, shape, quantity, size, motion and time. And so the truths of geometry seem secure.
- Descartes: ‘When I consider this carefully, I find not a single property which with certainty separates the waking statue from the dream. How can you be certain that your whole life is not a dream?’.
Outline and explain Descartes 3 waves of doubt (Evil demon). What is his response to ‘god is good so wouldn’t deceive.’?
-Descartes then casts doubt on even these claims of mathematics by questioning whether god may have deceived him.
To the objection that god is good and wouldn’t deceive him Descartes says:
-Suppose that god does not exist. Suppose all our experiences are being produced by an evil demon. We wouldn’t know. He can’t know anything unless he can rule out the possibility that he is being deceived by an evil demon. He has reached the point of global scepticism.
How does Descartes respond to scepticism? (Rational intuition, idealism, god).
- Use rational intuition and deduction, he begins with the cogito. He then builds on this by developing the theory of clear and distinct ideas. This leads him to argue that the truths of maths are indubitable.
- Still no certainty of the causes of sense perception, and so the existence of mind-independent physician objects. He can’t move beyond idealism at this point.
- His next move is proving god exists mainly through the concept of god (primarily that he’s not a deceiver and his omnipotence).
- Because God is not a deceiver, then god wouldn’t not allow incorrigible errors, but has given me the ability to form true beliefs and so I can dismiss the possibility of an evil demon- if an evil demon was deceiving me I would have no way of justifying my beliefs about the world.
- Because God can bring about anything that corresponds to a clear and distinct idea, and is not a deceiver, I can know that there are such physical objects, which I experience in perception.
What do empiricists say are the 3 types of knowledge? And an objection against this.
- They restrict the knowledge that we have to:
- (A priori) knowledge of analytic propositions and what can be deduced from them.
- (A posteriori) knowledge of synthetic propositions about the world outside one’s mind.
- Knowledge of our own minds.
- One Objection is that this restriction on knowledge is too severe. It leads to local scepticism across many branches of supposed knowledge. E.g. does god exist? And morality- moral claims such as ‘murder is wrong’; don’t appear analytic. What part of sense experience pick up on ‘wrongness’ and how?
- If empiricists can’t show that moral claims are either analytic or a posteriori, then they will be forced to conclude that there is no moral knowledge either.
Outline and explain how an empiricist would respond to global scepticism.
- Indirect realists (Locke, Russel and Trotter Cockburn) argue that we only immediately perceive sense-data, and we must infer the cause of our sense experiences.
- They defend the claim that an external world of physical objects is that cause on the grounds that it is the best explanation of our experience, in particular, that is involuntary, coherent between different senses and that is is synthetic.
What is one way we may we respond to this argument understood as a response to scepticism?
-First, Descartes argues that the existence of an external world remains a hypothesis, we can’t know for certainty that it exists.
- We can respond to this and say that he sets the bar for certainty far too high. Knowledge doesn’t require certainty.
- If the existence of physical objects is the best explanation of our sense experience, this is sufficient justification for us to know that they exist (if the belief is also true).
-This response rejects the demand for certainty.
What is the second way we can respond to the indirect realists claim that we must infer from our sense data? Does it stay strong?
-The second Objection challenges the claim that the existence of physical objects is the best explanation for sense experience. The brain in a vat explanation is just as strong!
- So inference to the best explanation cannot show that we can rule out the possibility of being brains in vats.
- So it doesn’t meet the challenge of global scepticism.
How does Berkeley respond to scepticism? What is a challenge to this and why does this challenge fail?
-He removes the challenge of scepticism by rejecting the distinction between appearance and reality. What we experience is reality. Idealism has no need to discover how our perceptions of physical objects relate to reality. In experiencing ideas, we experience what exists.
- Berkeley infers that something outside my mind must cause my perceptions, and given then complexity of my experience that something must be God.
- But could it be a supercomputer instead? Berkeley argues that this is still a physical object and we have no reason to think that physical objects exist independent to minds: the thought experiment is incoherent.
