Revise Philosophy for AS Level

Michael Lacewing

• Éditeur: Routledge
• Année: 2007
• ISBN:
  9781134147526
• Édition: 1
• Sujet: Philosophie
• Sous-sujet: Histoire et théorie de la philosophie

Revise Philosophy for AS Level is the definitive revision guide for students of the Advanced Subsidiary level syllabus. Following the AQA syllabus, it helps students revise using past exam questions, examiner's reports, and tips on revision for the examination. Also included are a helpful glossary and annotated further reading. It covers all three units of the AS Level syllabus:

• Unit 1: Theory of Knowledge
• Unit 2: Moral Philosophy and Philosophy of Religion
• Unit 3: Texts.

The four set texts are discussed: Plato's The Republic, Descartes' Meditations, Marx and Engels' The German Ideology and Sartre's Existentialism and Humanism.

Essential reading for all students of AS Level Philosophy, it is an ideal companion to the textbook Philosophy for AS and A2, also published by Routledge.

1
theory of knowledge
UNIT 1

I EMPIRICISM AND RATIONALISM

A priori and a posteriori knowledge

A priori knowledge is knowledge of propositions that do not require (sense) experience to be known to be true. Knowledge that can be established only through experience is a posteriori. The a priori–a posteriori distinction is about how to check or establish knowledge. It is not about how we acquire the concepts or words of the proposition. Babies are not born knowing that all bachelors are unmarried! Yet this is a truth that clearly doesn’t need testing against experience: we know it is true just by knowing what it means. Of course, we first have to learn what it means, but that is a different issue from how we check if it is true.

This contrast between a priori and a posteriori knowledge should be distinguished from another contrast, that between analytic and synthetic propositions. A proposition is analytic if it is true or false just in virtue of the meanings of the words. Many analytic truths, such as ‘All bachelors are unmarried’, are obvious, but some are not, e.g. ‘Your mother’s brother’s father’s niece’s sole female cousin is your mother’ (think about it!).A proposition is synthetic if it is not analytic, i.e. it is true or false not just in virtue of the meanings of the words, but in virtue of the way the world is, e.g. ‘snow is white’.

QUIZ QUESTION

Explain and briefly illustrate the meaning of a priori and a posteriori knowledge. (AQA, 1a, 2001, 6 marks)

Defining rationalism and empiricism

Philosophers do not agree on precisely how to define rationalism and empiricism. Obviously, rationalism gives an important role to reason, and empiricism to experience, but the terms range across theories of knowledge, theories of concept acquisition, theories of justification and historical schools of thought. Thinking of them just in terms of ‘reason’ versus ‘experience’ is much too simple – why should we think that we have to choose? Most rationalists (the exception is Plato) do not deny that experience can provide us with knowledge under certain circumstances; and empiricists clearly use reasoning, based on experience, to construct arguments about what we know. Furthermore, we need to qualify just what is meant by ‘reason’ and ‘experience’.

Nevertheless, there is a way of contrasting rationalism and empiricism that makes them exclusive (no one is both a rationalist and an empiricist), and which goes to the heart of the historical debate. Stephen Law puts it like this: rationalism claims that we can have synthetic a priori knowledge of how things are outside the mind; empiricism denies this.

In other words, rationalists argue that it is possible for us to know (some) synthetic propositions about how the world outside our own minds is – e.g. about mathematics, morality or even the material world – without relying on sense experience. Empiricists argue that it is not. Notice that they don’t deny all a priori knowledge – no empiricist claims that you have to check whether all bachelors are unmarried to see if it is true! They simply claim that all a priori knowledge is of analytic propositions. If we don’t know if a proposition is true or false just by the meaning of the words, we have to use sense experience to find out whether it is true or false.

(The clause ‘how things are outside the mind’ is necessary. Many propositions about my mental states are synthetic, e.g. ‘I feel sad’ or ‘I am thinking about unicorns’. But they don’t require sense experience to be known; in fact, does knowing my own thoughts involve experiencing them at all? We don’t need to worry about this. Rationalists and empiricists alike do not deny that we just do know that we have certain impressions and ideas, thoughts and feelings. The argument is about knowledge of things other than our own minds.)

KEY POINTS

• Rationalism claims that we can have synthetic a priori knowledge of how things are outside the mind.
• Empiricism denies this. It claims that all a priori knowledge is only of analytic propositions.

Rationalism: reason as the source of our knowledge, as justification for our beliefs and as the source of our conceptual apparatus

Rationalists claim that we have synthetic knowledge that does not depend upon sense experience. How do we gain such knowledge? Rationalists argue either that we have a form of rational ‘intuition’ or ‘insight’ which enables us to grasp certain truths intellectually; or that we know certain truths innately, as part of our rational nature; or both. Rationalists may also argue that some of our concepts are innate – that although it might take sense experience to make us aware of these concepts, the content of the concept is not given by experience.

Many rationalists add that the knowledge we gain through reason or have innately cannot be had in any other way. They may also argue that such knowledge is superior, e.g. by being more certain, to the knowledge or beliefs we gain through the senses.

Plato

Plato argues that we can have knowledge only of the Forms, which are abstract entities we can know through reason, but not through sense experience. He argues that we can never have knowledge through sense experience, we can form only opinions. His theory of knowledge is discussed in the first four sections of Ch. 4 (THE THEORY OF FORMS p. 194; KNOWLEDGE, BELIEF AND IGNORANCE p. 196; THE SIMILES OF THE CAVE AND THE DIVIDED LINE p. 198; EPISTEMOLOGICAL IMPLICATIONS OF THE THEORY OF THE FORMS p. 201). Since that discussion of knowledge and reason is self-contained, I discuss only Plato’s theory of concepts here.

Plato doesn’t just argue that we can have knowledge only of the Forms. He also argues that our concepts are derived from the Forms. In the Phaedo, he argues that learning must be a kind of recollection. When we learn, we become able to apply concepts to what we experience, which involves knowing what ‘equality’ or ‘beauty’ or ‘rose’ means. Where do these concepts come from? If all we have are many and various experiences, how are we able to classify experiences? We might argue that we classify experiences, and so form concepts, through similarities and differences between our experiences. But in order to know what is ‘the same’ or ‘different’, we must already be able to classify our experiences. But we can’t do so unless we already have concepts! So we can’t form concepts by classifying experiences.

So, Plato argues, we have concepts innately. Concepts are our recollection of the Forms, which we (our souls) experienced before birth. Unless we have this innate knowledge, we could never learn anything.We are able to classify our experiences by comparing them with our innate concepts (memories of the Forms). (Plato doesn’t argue that we realize this is what we are doing.)

A second argument against thinking that concepts derive from experience is that because we all have different experiences, we’ll all form different concepts. But then how can we talk to each other and share ideas? Yet we do mean the same thing by the same word, so our concepts can’t be formed by our different experience, but by something we all share, viz. innate knowledge of the Forms.

Descartes

Unlike Plato, Descartes does not deny that we can have knowledge of the objects of sense experience. But we only gain that knowledge through the use of reason; it is reason which justifies our beliefs about the world. Descartes’s theory is discussed at length in Ch. 5 (see especially SCEPTICAL DOUBT AND ITS USE IN THE QUEST FOR CERTAINTY, p.; THE WAVES OF DOUBT, p.; ABSOLUTE CERTAINTY OF THE COGITO AND ITS IMPLICATIONS, p.; THE ESSENTIAL NATURES OF MIND AND BODY, p.; THE PROOF OF MATERIAL THINGS, p.; DESCARTES’S RATIONALISM, p.; and THE ROLE OF GOD IN DESCARTES’S SYSTEM, p.). I give a brief overview here.

Descartes begins his investigation into what we can know by attacking sense experience as untrustworthy. Most of what we think we know we have acquired this way, he says. However, appearances can be deceptive; e.g. objects far away look small. So what sense experience presents to us is too unreliable to count as knowledge.You can doubt even those sense experiences that seem most certain – e.g. that you are now reading a book – because you could be asleep, and, if you were, you wouldn’t know that you were (see Ch. 5, THE WAVES OF DOUBT, p. ). So sense experience, at least on its own, can’t give us knowledge.

Descartes then questions what we think material objects are. He notices that when he melts a piece of wax it loses all of its original sensory qualities (taste, smell, tactility, shape); yet he believes it is the same wax. So the wax is not equivalent to its sensory qualities. So when he thinks of the wax, he is in fact thinking about something that is extended and changeable. This is the essence of our idea of material objects, but it is given by reason, not sense experience. The idea of the wax as something defined by its sensory properties is muddled. When we realize that we comprehend the wax through understanding, as something extended and changeable, our idea of the wax has become clear and distinct (see Ch. 5, THE ESSENTIAL NATURES OF MIND AND BODY, p.).

Descartes goes on to argue that what is clearly and distinctly conceived is true (see Ch. 5, DESCARTES’S RATIONALISM, p.). So if material objects exist, then they really are extended. And he has shown this using reason. He then argues that we can know that material objects do exist (see Ch. 5, THE PROOF OF MATERIAL THINGS, p. ). We have experiences which appear, very forcefully, to be experiences of a world external to our minds. There are only two options for what might cause these experiences: a real external world; or God. If the cause was God, this would mean that God was a deceiver because he would have created us with a very strong tendency to believe something false. However, Descartes has also argued that God exists and is perfect by definition (see Ch. 5, THE TRADEMARK ARGUMENT and THE ONTOLOGICAL ARGUMENT, p. and p.). Because we know that God is perfect, we know that God is not a deceiver. So there must really be an external world.

In establishing what we know about material things, Descartes has relied on reason, and not sense experience, in three places:

1. in the argument that our idea of material objects as extended derives not from the senses, but from the understanding;
2. in his assertion that our experiences must have a cause, which for Descartes is a matter of logic (Hume rejects this claim – unless we already know that our experiences are effects, we can’t know by logic alone that they have causes);
3. in invoking God, since proving the existence of God depends on reason alone.

The first point is also the basis of Descartes’s claim that material objects are only extended; they don’t have, essentially and in themselves, those properties of colour, smell and so on that we seem to detect through our senses. So what we can know about material objects in general is completely dependent on reason. Having established this, Descartes is quite happy that our senses inform our understanding about particular objects, which then judges whether they exist or not.

Descartes also shows his rationalism in his claim that the idea of God is innate, rather than acquired from experience (see Ch. 5, THE TRADEMARK ARGUMENT, p. ).

KEY POINTS

• Plato argues that we can have knowledge only of the Forms, not of objects of sense experience, and that we gain this knowledge through reason.
• He also argues that our concepts are innate memories of the Forms. Unless we had such innate memories, we wouldn’t be able to classify experience using concepts.
• Descartes argues that reason is needed to establish the nature and existence of material objects in general and the existence of God. Sense experience provides only information about particular material objects, and even then our understanding judges whether they exist or not.
• Descartes also argues that the idea of God is innate.

QUIZ QUESTIONS

Explain and illustrate the rationalist view that some concepts are not drawn from experience. (AQA, 1b, 2003, 15 marks)

Outline Plato’s argument that we cannot have knowledge about the objects of sense experience.

Outline Descartes’s argument that we know the nature of material objects using reason not sense experience.

Outline Descartes’s argument for the claim that we can know that material objects exist.

Empiricism: experience as the source of our knowledge of concepts and propositions, and the means by which we justify our beliefs

Hume argues that we can have knowledge of just two sorts of things: the relations between ideas; and matters of fact. His distinction was developed by later philosophers, and is now understood in terms of the two distinctions, mentioned above: analytic–synthetic and a priori–a posteriori. Hume argued that all a priori knowledge must be analytic, while all knowledge of synthetic propositions is a posteriori. In other words, anything we know that is not true by definition, every ‘matter of fact’, we must learn and test through our senses.

The relations of ideas don’t depend on matters of fact, so we can know these a priori, through rational proof. By relations of ideas, Hume means propositions such as ‘All sons have fathers’ (about the ideas ‘son’ and ‘father’) and ‘If A is longer than B, and B is longer than C, then A is longer than C’ (about the idea of length). This seems uncontroversial so far. But an area of knowledge that has proved problematical for empiricists is mathematics, which I discuss further in THE LIMITATIONS OF EMPIRICISM (, p.).

All knowledge of matters of fact, by contrast, relies on experience.We gain it by using observation, and by employing induction and reasoning about probability. The foundation of this knowledge is what we experience here and now, or can remember. Hume argues that all our knowledge which goes beyond what is present to our senses or memory rests on causal inference. If I receive a letter from a friend with a French postmark on it, I’ll believe that my friend is in France – because I infer from the postmark to a place. I do this because I think that where something is posted causes it to have the postmark of that place; and if the letter was posted by my friend then I believe that he must be in France.

And how do I know all this? I rely on past experience – in the past, I have experienced letters being posted, I have seen different postmarks, I have found that postmarks relate to where you post something, and so on. I can’t work out what causes what just by thinking about it. It is only our experience of effects following causes that brings us to infer from the existence or occurrence of some cause to its effect, or from some effect to its cause.

Going further: empiricists on moral and religious knowledge

The debate between empiricists and rationalists has historically focused on knowledge of the material world. As a result, empiricists concentrated on sensory experience. But knowledge of the material world may not be all the knowledge we can have. So how have empiricists dealt with the question of moral knowledge and knowledge of God’s existence?

Empiricists deny that there is any synthetic a priori knowledge of how things stand outside the mind. So for any area of knowledge, they have three options:

1 to deny that we have any knowledge in that area;

2 to say that any knowledge we do have is based on experience; or

3 to say that any k...