In Berkeley’s Principles of Human Understanding (I got a version from http://www.earlymoderntexts.com/) I am fascinated by his extreme ontological and epistemolgical views, as I believe most people are, and I wanted to try to pin-point why they, in my opinion, feel so wrong.
Berkeley’s famous thesis that “to be is to be perceived” is a genuine conundrum on some levels. It says that matter cannot be the cause of our ideas through perception but rather ideas are the only things that can cause ideas. Now, this isn’t his entire argument but I feel one of Berkeley’s greater arguments comes in section 18.
The argument, more or less, goes like this:
1.) If matter exists then either we know matter by our senses or we know it by reason.
2.) We can’t know matter by our senses.
3.) We can’t know matter by reason.
4.) Therefore, matter does not exist.
The argument is deductively valid. If we created a conjunction of premises 2 and 3 we can them apply DeMorgan’s law to arrive at the negation of a disjunction thus creating a modus tollens move to the conclusion (the negation of the antecedent of the conditional in premise one). However, let’s look at the text to see why Berkeley believes premises 1, 2, and 3.
Premise 1 is derived from this text here:
“Suppose it were possible for solid, figured, movable substances to exist outside the mind, corresponding to the ideas we have of bodies—how could we possibly know that there are any such things? We must know it either by sense or by reason.”(Berkeley S.18)
This quote is invaluable since we see that we are not just talking about matter but we are considering matter that has the quality of providing our ideas of bodies.
Premise 2 is justified by Berkeley’s ideas of sense perception. For Berkeley, your senses only inform you of the idea of an object. This is because when you are seeing an object you are merely having an idea of the object. There is an identity between ideas, sensations, and things immediately perceived by sense as shown here “Our senses give us knowledge only of our sensations—ideas—things that are immediately perceived by sense—call them what you will…”(Berkeley S.18). So for Berkeley, this gives you no justification to believe in some object that exists unperceived (or outside the mind) that resembles the objects of our perception.
Premise 3 is justified by two key thoughts for Berkeley: There is no necessary connection between material things and our ideas; we could have all the same ideas and thoughts without any outside bodies existing (the evidence is found dreams and hallucinations according to Berkeley). So because of these two facts we should not infer from our reason that matter does exist.
I agree with premise 1 but take issue with premises 2 and 3. I believe there is a problem with the justification for each premise.
The justification for premise 2 has many flaws in its reasoning. Remembering Berkeley’s reasoning that sensations only inform us of our sensations, we have a statement that is true but boringly so (or tautologous in nature) . It is more interesting when one considers the identity that we established earlier that replaces sensations with ideas but this seems like question begging. If our senses only give us the power to know of ideas then you have already limited the human mind to never knowing the physical objects in question. It seems plausible, and consistent, that matter can interact with matter, if we are in fact just matter. Verily the mind body problem caused these confusions for Berkeley “The materialists admit that they cannot understand how body can act upon spirit…” (Berkeley S.19). And if the materialists of his day had a dogma of the soul holding them back then surely Berkeley had his reasons to be confused. Furthermore, I find it odd that Berkeley would choose such an extreme position simply because they were having a problem uniting the mind with the body.
The justification for premise three has problems as well. Remember that Berkeley gave us two reasons that we cannot infer matter’s existence from reason: there is no necessary connection between material things and our ideas and we could have all the same ideas and thoughts without any outside bodies existing. The first reason he gives is also question begging. If it were that case that physical objects caused our ideas through sense perception then we would have necessary connection between physical objects and our ideas. It seems that status of these objects is determined at the beginning of the question. The second reason given seems to be a case of bad reasoning. When astronomists of the 1400′s and 1500′s were choosing between the new Copernican model or the old Ptolemaic model we could have, as Berkeley seems to think, just stayed with the Ptolemaic model. After all, Ptolemy could make sense of retrograde motion of stars and other phenomena that Copernicus was trying to solve. So since we don’t need Heliocentrism why bother? I feel this Berkeley argument is analogous, just because we don’t need matter (on his theory) it doesn’t mean it isn’t there.