Berkeley's empiricism

 

1    What experience teaches

Descartes' rationalism thus has a rather weak point in it: the proof of God's existence on the basis of pure reason alone.  And as such his justification for the reliability of the senses is suspect.  But the question now arises: why should anybody doubt the reliability of the senses. Is not the fact that I see the table justification enough for believing that there is a table?  Does not the chain of justification come to a halt in my own visual, tactual, auditory experiences of the world?  This kind of claim is characteristic of empiricism: that knowledge is justified by experience.

    Certainly some experiences show that there is something wrong with the principle of begging the question which generates the sceptical regress. Consider

Proposition P: I am experiencing intense pain.
Surely I can know that P is true without having to justify my belief by appealing to some proposition distinct from P.  If somebody asks me 'Why do you believe you are experiencing intense pain' I could answer, quite justifiably 'Because I am experiencing intense pain.'  In this case the truth of P  is a perfect justification for believing P.   It is rationally permissible in this case to appeal to P as my justification for believing P.   So there does seem to be a foundation in experience for some knowledge.  It seems that I can know what my experiences are on the basis of those very experiences.

     The trouble is that this is knowledge only about myself (whether or not I am in pain, whether or not I am now experiencing a table etc).  It is not knowledge of the external world, as presented to me by the senses.  Perhaps I can know, on the basis of my experience, that I am now having a visual experience of a table in front of me.  But can I know, on the basis of  those visual experiences, that there really is a table in front of me?  Can I turn certainty about my own experiences into certainty about an external world?

     One way of bridging the gap between my own experiences and the external world would be to deny that there really is an enormous gap.  This was Bishop Berkeley’s idealist strategy.
 
 

2    Berkeley's idealism

According to Berkeley, external objects are not strange entities existing independently of minds, entities which lie behind our experiences and give rise to them.   The very notion of an object which exists independently of all minds is, accordingly to Berkeley, incoherent.  Rather, what we call external objects are really just collections of experiences.  Physical objects really are smelly, coloured, tasty ....and all the other features which we perceive them to have.  That’s because a physical object is nothing more than the total collection of experiences with which it is identified.  Thus it is that through immediate sense experience we can know things about physical objects.

    Berkeley took the arugments for the mind-dependence of the so-called secondary qualities (colours, tastes, feels etc) and showed that analogous arguments for the mind-dependence of the so-called primary qualities (shape, motion, micro-structure) were just as good.  Thus all the qualities of perceptual objects are mind-dependent.  The whole "external" world is one big collection of mind-dependent things.
 

3    Berkeley's master argument

Although he used various arguments of his predecessors for the mind-dependence of the secondary qualities , Berkeley also  discovered a range of new arguments.  Here is a particular interesting one:
 
Hylas:  What is more easy than to conceive a tree or house existing by itself, independently of, and unperceived by, any mind whatsoever?
Philonus Hylas: can you see a thing which is at the same time unseen?
Hylas No that is a contradiction.

Philonus  Is it not as great a contradiction to talk of conceiving a thing which is unconceived?

Hylas It is.

Philonus  The tree or house, therefore, which you think of is conceived by you?

Hylas How should it be otherwise?

Philonus How then came you to say you conceived a house or tree existing independently and out of all minds whatsoever?

Hylas That was an oversight ...

Philonus You acknowledge then that you cannot possibly conceive how any one corporeal sensible thing should exist otherwise than in a mind?
 

We can think of this argument as a reductio of realism.
 
REALISM There are some things which exist outside all minds, and anything which exists outside all minds could exist unconceived (= not conceived by anybody).
The argument really uses just two premises:
1  If it is possible for a thing to exist then one can conceive of such a thing.
2  One cannot conceive of a thing without that thing being conceived (i.e. by oneself).
From 1 we get:
1*  If it is possible for an unconceived thing to exist, then one can conceive of such a    thing.
And from 2 we get:
 
2*  One cannot conceive of a thing which is unconceived.
1*+ 2* entail

  It is not possible for an unconceived thing to exist.

And that refutes realism.  (Help!)
 
 

4    Another problem: induction

Whether or not Berkeley’s analysis of physical objects is correct, we still run into another gap problem.  We believe all sorts of things about the universe which are not based on immediate sense experience.   In particular we have all sorts of beliefs about the future which we think are entirely rational.  But how can information solely about the  present and the past tell us about the future?  We run into the problem of induction.