Week 7: Knowledge and Skepticism

Chapter 4: The Rationalist

According to Rationalism at least some knowledge can be had through reason alone.

Empiricism, on the other hand, takes all of our knowledge to be ultimately grounded in sense experience.

Comparing the Two:

In a nutshell, rationalism is like saying, "I can solve this puzzle by thinking deeply and using my brainpower," while empiricism is like saying, "I need to go out, see things, touch things, and learn through direct experience."

Rene Descartes was the first significant rationalist philosopher of the modern classical period

Following Descartes, a number of other European philosophers develop rationalist philosophical systems. Leibniz and Spinoza are the most notable.

The three major empiricist philosophers are John Locke, George Berkeley and David Hume.

Skepticism is the view that we can’t know.

Dualism: According to this view, the world is made up of two fundamentally different kinds of substance, matter and spirit (or mind). Material stuff occupies space and time and is subject to strictly deterministic laws of nature. But spiritual things, minds, are immaterial, exist eternally, and have free will.

The intractable problem for Descartes’ dualism is that if mind and matter are so different in nature, then it is hard to see how they could interact at all.

Determinism is the view that all physical events are fully determined by prior causal factors in accordance with strict mechanistic natural laws

Descartes' project in his Meditations is to carry out a rational reconstruction of knowledge. All we have immediate intellectual access to is the contents of our own minds. How can we ever have knowledge of anything beyond the contents of our own mind based on this? This is the problem of Cartesian skepticism.

Descartes is a substance dualist. This is the metaphysical view that the world is made up of two fundamentally different kinds of substance

Spinoza is alternately described as the “God-intoxicated man”. Spinoza defines God as a being that is infinite, where being infinite entails being unlimited. So, argues Spinoza, there is only one substance, and it is both God and nature. Every facet of the world is a mere part of this one substance, God/nature.

Spinoza’s view is that mind and body are one and the same limited modification of God, understood on one hand through the attribute of thought and on the other through the attribute of extension. A better way to put this might be to just say that the mind is the idea of the body.

Leibniz (1636-1716): He took the world to consist of monads. Each monad is simple and indivisible. But monads are not merely physical, like atoms. Each monad would include both a physical aspect and a mental aspect, a view known as panpsychism. Physical objects are made up of monads that are also minds, just particularly dim-witted ones. Monads appear to interact with each other. We seem to influence each other and make things happen in the physical world. But according to Leibniz there is no actual interaction between monads. Instead, monads exist in a harmony that is pre-established by God. As a result, like an element in a spectral image or a droplet in a cloud, each monad carries in it a reflection all of creation.

The problems Leibniz is trying to negotiate in the wake of Descartes and Spinoza:

1. The problem of mind/body interaction looms large after Descartes. If mind and body are distinct kinds of substances, then it is very hard to see how either can have any influence on the other. Leibniz metaphysics handles this problem neatly by making his substances, monads, have mind as an integral part. We needn’t worry about mind-body interaction if mind and body are already unified. 2. Leibniz is eager to provide a philosophical route to avoiding Spinoza’s atheism and denial of free will. To avoid atheism, and in particular a variety of atheism where people are mere parts of an impersonal God/nature, Liebniz needs to posit a plurality of substances. Monads fit the bill. In order to preserve free will, which is also central to Christian theology, Leibniz needs for the substances that are mind not to be causally determined by other substances. The pre-established harmony of monads is his means of achieving this. But while Leibniz thereby avoids causal determinism, he seems to be saddled with a kind of theological determinism instead.

Chapter 5: The Empiricists

Empiricism is the view that all of our knowledge is ultimately acquired through by sense experience. This chapter discusses three major empiricist thinkers: John Locke, George Berkeley, and David Hume.

John Locke (1632 –1704): Locke develops his empiricist epistemology in his Essay Concerning Human Understanding. Locke’s approach is to examine the origins of the contents of the mind. Early in this work he argues against innate ideas. The mind starts off as a tablula rasa, a blank slate. All of our ideas have their origin in experience. Simple ideas, say of solidity and figure, are acquired through the senses, and from these we form complex ideas, say the idea of a dog, through the capacities of the understanding. Locke thinks that some of the impressions we get from sense experience are genuinely similar to how things are objectively in the world. Our sense experience of the shape of things, for instance, reflects the ways things really are according to Locke. Locke uses the term "primary qualities" for qualities in which there is a resemblance between our experience and the way things are. The taste of an apple, for instance, is not really in the apple. What is in the apple is just a power to produce the experience of a certain flavor. But we have no grounds for thinking that this power as it exists in the apple resembles in any way the sense experience we have of its taste. Secondary qualities, in Locke's terminology, are qualities for which our sense experience does not resemble the corresponding qualities in objects that give rise to our experience. Our knowledge of the external world, then, is based entirely on our experience of the primary qualities. So given simple ideas through experience, the operations of the mind become a source for further ideas. Locke thinks knowledge of the self, God, mathematics, and ethics can be derived from this additional internal source of experience.

George Berkeley (1685-1753) is best known for arguing for idealism ( idealism is the view that there is no physical substance underlying our sense impressions of the world. Rather, the world consists entirely of ideas. Your mind is just a bundle of impressions, and there is nothing in the world except for so many minds having their various perceptions) on empiricist grounds.

Berkeley’s argument attacks Locke’s distinction between primary and secondary qualities and argues that all of our sense impressions are mere appearances and that we have no grounds for thinking that any of them bear any resemblance to the way things are. Since we lack any empirical experience of the underlying substances in which qualities inhere, we have no empirical reason to suppose underlying substances even exist.

David Hume (1711-1776): The twentieth century begins with a movement known as Logical Positivism that tests the limits of Empiricism. The Empiricism of the Logical Positivists is heavily indebted to Hume.

Hume’s empiricist epistemology is grounded in his philosophy of mind. Hume starts by asking what we have in the mind and where these things come from. He divides our mental representations into two categories, the relatively vivid impressions, these include sensations and feelings, and the less vivid ideas which include memories and ideas produced by the imagination

A priori reasoning, which is reasoning independent of experience, can produce understanding of relations of ideas. Mathematical and logical reasoning is like this.

Our ability to understand matters of fact, say truths about the external world, depends entirely on a posteriori reasoning, or reasoning based on experience.

The result of Hume’s rigorous empiricism is skepticism about a great many things.

Hume's view on causation: When we look about us towards external objects, and consider the operation of causes, we are never able, in a single instance, to discover any power or necessary connection; any quality, which binds the effect to the cause, and renders the one an infallible consequence of the other. We only find, that the one does actually, in fact, follow the other. The idea of causes necessitating their effects, according to Hume’s analysis, is a confused projection of the imagination for which we find no basis in experience. For this reason, Hume denies that we have rational grounds for thinking that causes do necessitate their effects. So basically…Imagine you have a pet turtle named Turtley. Every time you give Turtley some food, he gets really excited and starts moving around. So, in your experience, feeding Turtley (event A) is always followed by his excitement and movement (event B). Now, David Hume would say that when you think about it, you believe that feeding Turtley causes him to get excited because you've seen it happen over and over. But, according to Hume, you don't actually see any magical connection between the food and Turtley's excitement. You just notice that one thing tends to happen after the other. Hume would say that your belief in causation is like a habit. Because you've seen these events happen together repeatedly, your mind expects that when you feed Turtley again, he will get excited. It's a bit like when you hear a bell ring, and you expect that recess is over because that's what usually happens. Hume also says there's no "magic link" that forces Turtley to get excited when you feed him. Just because it happened before doesn't mean it has to happen every time. Maybe one day, Turtley decides he's not in the mood to get excited even though you fed him.

Our beliefs about the external world, for instance, are based on the idea that things going on in the external world cause our sense impressions. We have no rational grounds for thinking so, says Hume.

Closely related to Hume’s skepticism about causation is Hume’s skepticism about inductive reasoning. Inductive argument, in its standard form, draws a conclusion about what is generally the case, or what will prove to be the case in some as yet unobserved instance, from some limited number of specific observations.

Hume's skepticism about induction is like saying you can't be 100% sure about things just because they've always happened a certain way in the past. It's a bit like thinking that every day will be sunny because it has been sunny for a week. Hume would caution against making absolute predictions based on what you've observed so far.

Hume's skepticism about God is rooted in his empiricism, his critique of the evidence for miracles, his questioning of causal reasoning, and his observation of anthropomorphic tendencies in religious thinking. He did not outright deny the existence of God but encouraged a critical examination of religious beliefs, urging people to rely on empirical evidence and rational inquiry.

Hume’s view on The Self: The contents of our immediate experience are just particular impressions and ideas. But we have no experience of any single unified self that is the subject of those experiences. The idea of a self, including the idea of the self as a soul, is a fanciful projection from our experiences. All we can say in an empirically grounded way of ourselves, according to Hume, is that we are just a bundle of experiences.