perception as a source of knowledge

• the role of God argument (2) response


  Berkeley holds that we perceive copies of the ideas in God's mind. These ideas don't exist in God's mind as perceptions, but as part of His understanding.
• the role of God argument (2)


  If all ideas exist in the mind of God- He must then experience pain as we do
• the role of God argument (1) response

  Berkeley offers a choice: the incoherent concept of matter, or the coherent notion of a divine mind sustaining all thingsBerkeley would argue: I never assumed that God exists. Instead, I infer his existence from the existence of the ideas we experience
• the role of God argument (1)


  In order to secure his ideas on perception, Berkeley resorts to the existence of God.Without God, doesn’t his whole philosophy fall down?
• What of hallucinations? If all we perceive are ideas, then we are left with the conclusion that real things are no different from imaginary ones—both seem to be fleeting figments of our own mindsIf, as Berkeley argues, “to be is to be perceived” does this therefore mean that hallucinations are just as real as perception?Also, why would God cause such perceptions?
• The pencil looks crooked in the water- but I know I isn’t- it doesn’t feel crooked or look it when I pull it out of the water.
• solipsism explained

  Berkeley's earlier argument - that everything one perceives is mind-dependent - suggests that there is no reason to believe anything exists beyond one's experience.I never perceive other minds, all I perceive are ideas - so what reason do I have to believe that other minds exist at all?

  
• what is solipsism?


  the view that one’s mind is the only mind that exists.
• what are the issues with berkeley's idealism?

  . arguments from illusion and hallucination. idealism leads to solipsism. problems with the role played by God in berkeley's idealism (including how can berkeley claim that our ideas exist within God's mind given that he believes that God cannot feel pain or have sensations?) and responses to these issues
• berkeley's argument of 'God as the cause

  
• response to the master argument

  However, the conclusion does not necessarily follow: just because it’s impossible to have an idea of a mind-independent object, it doesn’t mean that mind-independent objects are themselvesimpossible.
• example in the master argument? (2b)

  The dialogue (between Hylas and Philonous) for the master argument can be summarised as:P: Try to think of an object that exists independently of being perceived.H: OK, I am thinking of a tree that is not being perceived by anyone.P: But that’s impossible! You might be imagining a tree in a solitary place with no one perceiving it – but you’re still thinking about the tree. You can think of the idea of a tree, but not of a tree that exists independently of the mind.
• what is the master argument (2b)

  Berkeley’s master argument is essentially that we cannot even conceive of a mind-independent object because as soon as we conceive of such an object, it becomes mind-dependent. Thus, mind-independent objects are impossible.
• berkeley's attack on the primary/secondary quality distinction (2a)

  Recall Locke’s notion of primary qualities as those that we cannot (in contrast to secondary qualities) conceive of an object as lacking.Berkeley argues that we cannot, in fact, conceive of such an object –secondary qualities (which emerge from the sense data we perceive) – are all there is to an objectFurthermore, if secondary qualities are (if one misreads Locke!) wholly mind dependent because they vary between perceivers, then primary qualities also fall into this category.
• what is Berkeley's idealism? (spec)

  . the immediate objects of perception (i.e. ordinary objects such as tables, chairs, etc) are mind dependent objects. arguments for idealism including berkeley's attack on the primary/secondary quality distinction and his 'Master' argument
• Berkeley's Idealism


  Sense data = ‘ideas’ (hence, idealism)Physical objects are mind-dependent; they are collections of ideasThe position is, therefore, antirealist with regards to matterIn Berkley’s view, there are only ideas perceived in the mindBerkley’s view is notsolipsistic – there are other minds out there (including God’s!)
• Berkeley's attack on locke simplified


  . When we perceive an object, we don't perceive anything in addition to its primary and secondary qualities. So, everything we perceive is either a primary quality or a secondary quality. Secondary qualities are mind-dependent. Primary qualities are also mind-dependent. Therefore, everything we perceive is mind-dependent
• Berkeley's attack on locke? (*)

  Berkeley uses Locke’s distinction between primary and secondary qualities against him to argue for a mind-dependent worldHe says the only things we perceive are qualities and nothing moreHe agrees with Locke that secondary qualities are mind-dependent using an example of being burnt by fireHowever, Berkeley disagrees with Locke on primary qualities as he argues they are also mind-dependentHe uses the argument from perceptual variation to back this upTherefore, everything we perceive (as we only perceive primary and secondary qualities) is mind-dependent and there is no independent external world
• Berkely and idealism?

  Bishop George Berkeley (1685-1753) is the most famous proponent of idealism.
• idealism explained?

  idealism claims that there is no external world independent of minds - means that we are perceiving ideas directlyThe immediate objects of our perception are mind-dependent ideasThe only things that exist are minds and what minds perceiveIf something is no longer being perceived, it no longer exists
• what is idealism?

  There is no external world independent of minds (so it can be labelled an anti-realisttheory)We perceive ideas directly
• OVERALL issues with indirect realism

  . bertrand russell's réponse that the external world is the 'best hypothesis'. locke's argument from the involuntary nature of our experience. the argument from the coherence of various kinds of experience, as developed by locke and trotter-cockburn. the argument from george berkeley that we cannot know the nature of mind independent objects because mind-dependent ideas cannot be like mind-independent objects
• Berkley's response (*)


  the argument from george berkeley that we cannot know the nature of mind independent objects because mind-dependent ideas cannot be like mind-independent objects
• Trotter-Cockburn's argument comparing perceptual experiences from different senses


  one object can cause perceptual experiences through different senses, these experiences can be very different i.e. sight and hearing. We learn which go together so we can infer one experience to another. Why would we be able to confirm our experiences using a different sense + be able to predict them unless there is something both senses perceive that is independent of being perceived by a particular sense?
• Locke's argument comparing perceptual experiences from different senses (2)


  our different senses confirm information supplied by one another i.e. “if I see a fire and doubt whether it is real, I can confirm its reality through touch”
• Locke and Trotter-Cockburn??

  Locke and Trotter-Cockburn both give arguments comparing perceptual experiences from different sensesTC wrote this in a letter to Berkeley responding to an argument he makes about idealism (comes next)
• counter response to locke's reply (??) not on spec

  But does this really succeed in defeating the sceptical challenge? The information you hear may be equally misrepresentative of the external world as the information you see.
• Locke's reply (??) not on spec

  Second, Locke argues that the different senses confirm the information of one another. For example, you can write something on a piece of paper and see the words. Then, you can get someone to read the words out loud and thus hear the same information via a different source.
• counter response to locke's reply (1)

  However, even if Locke succeeds in proving something external, he doesn’t succeed in proving that sense data is in any way an accurate representation of the external world. The sceptic could argue that the external world may be completely different to our perception of it and there’s no way we could know.
• Locke's reply (1)

  Locke argues that there is an involuntary nature to experienceWe cannot avoid having certain sense-data produced in our mindHowever, in memory and imagination we can choose what we experienceTherefore, perceptual experiences "which I have whether I want them or not - must be produced in my mind by some external cause" i.e. physical objects
• russell's response (1) general form


  P1. Either physical objects exist and cause my sense-data or physical objects do not exist and do not cause my sense-dataP2. I can’t prove either claim is true or falseC1. Therefore, I have to treat them as hypothesesP3. The hypothesis that physical objects exist and cause my sense-data is betterC2. Therefore, physical objects exist and cause my sense-dataTHE EXTERNAL WORLD IS THE BEST HYPOTHESIS
• counter response to russell's response (??) not on spec


  Russell rejects his own argument as he realised that he was assuming something that we cannot know, that there are other people and that they have sense data which is similar to mine (P2).
• russell's response (1)

  Bertrand Russell, an indirect realist, concedes that there is no way we can conclusively defeat this sceptical argument. However, he argues that the existence of a mind-independent external world is the best explanation for sense data.
• Russell's response (??) not on spec

  P1. The fact that sense data are private means that no two people actually ever perceive the same thing, unless we can say that there are physical objects that they perceive (indirectly).P2. People have very similar sense-data if they are at the same place and timeP3. The best explanation of this is that here are physical objects causing their sense data: they both perceive the same physical objectC1. So physical objects exist
• indirect realists who respond to scepticism

  Bertrand Russell (x1), John Locke (x2), Trotter-Cockburn (x1) and George Berkeley (x1??)
• example of scepticism

  Look at the two diagrams. What would be the difference from the perceiver’s perspective between the two? What difference would it make to the perceiver if there was no physical world at all?The answer, surely, is nothing.

  
• veil of perception?

  A veil of perception exists between our sense-data and the object which we cannot get past (because if all we perceive is sense-data we have no way of knowing whether it is accurate representation of an external world, or if there even is an external world). We cannot then provide any evidence for the claim that there is an external world as indirect realists do, as all we can perceive is sense-data.
• scepticism explained


  If we only perceive sense data, and not the object itself, how can we know anything about the external world? There is no way of telling if the sense data is an accurate representation of the external world - or even that there is an external world at all!
• what does the issue of scepticism seem to point to?

  a veil of perception
• what is a problem for indirect realism?

  it leads to scepticism about the nature and existence of the external world.