2Idealism Idealism: nothing exists that exists independently of minds. Berkeley: To be is to be perceived (or to perceive): esse est percipi (aut percipere)What is a material object, exactly? We think it is ‘mind-independent’, but does this make sense?
3Why idealism?Objection to naïve realism: secondary qualities are subjective, so we don’t perceive objects just as they are.Objection to representative realism: primary qualities do not ‘resemble’ objects any more than secondary qualities do.So no qualities of ‘material objects’ are mind-independent; we perceive only ‘ideas’. Material objects are just bundles of ideas.If we are not idealists, we will fall into confusion or scepticism.
4What causes perceptions? Options: ideas, my mind, another mindNot ideas: they are passiveNot my mind: perception is very different from imaginingSo another mind - given the systematicity and complexity of what we perceive, that mind must be GodIs appealing to God any worse than appealing to material objects? They don’t explain perception either, e.g. how do they cause ideas?
5Illusion and realityHow do I distinguish my ideas from reality (ideas outside my mind)?A perception is not voluntaryThe idea perceived is part of the order of nature (coherent reality)The idea is caused by the mind of GodWhat of illusions?We aren’t wrong - it is bent. But we make a mistake if we think it would still be bent out of water. To mark this, we rightly say, ‘The pencil looks bent’.
6In, out, in, outWhen objects are not being perceived, then they don’t exist!There was a young man who said, Godmust find it exceedingly oddwhen He finds that the treecontinues to bewhen no one’s about in the Quad.Courtesy of UCL
7Reply 1To say an object of perception exists is to say that it is or can be perceived.But this conflicts with esse est percipi - to be is to be perceived.But should we worry if objects pop in and out of existence if they do so with complete regularity?
8Reply 2: God’s response Dear Sir, your astonishment’s odd, I’m always about in the Quad.And that’s why the treecontinues to besince observed by, yours faithfully, GodIdeas we perceive are not just caused by God’s mind, but exist in God’s mind
9A final objectionGod’s mind can’t contain the kind of perceptions (partial, visual, etc.) that we have.God is said to be unchanging, but reality changes all the time.Response: the ideas don’t exist in God’s mind in this way (as thoughts). What we see is what God wills us to perceive (so they exist as intentions).