Analytic Philosophy Gottlob Frege: Sense and reference: One of his primary examples involves the expressions “the morning star” and “the evening star”. Both of these expressions refer to the planet Venus, yet they obviously denote Venus in virtue of different properties that it has. Thus, Frege claims that these two expressions have the same reference but different senses. The reference of an expression is the actual thing corresponding to it, in the case of “the morning star”, the reference is the planet Venus itself. The sense of an expression, however, is the “mode of presentation” or cognitive content associated with the expression in virtue of which the reference is picked out. (IEP)

Meaning The reference of an entire proposition is its truth-value, either the True or the False. The sense of a complete proposition is what it is we understand when we understand a proposition, which Frege calls “a thought” (Gedanke). Just as the sense of a name of an object determines how that object is presented, the sense of a proposition determines a method of determination for a truth-value. The propositions, “2 + 4 = 6″ and “the Earth rotates”, both have the True as their references, though this is in virtue of very different conditions holding in the two cases, just as “the morning star” and “the evening star” refer to Venus in virtue of different properties.

Bertrand Russell Three passions, simple but overwhelmingly strong, have governed my life: the longing for love, the search for knowledge, and unbearable pity for the suffering of mankind. These passions, like great winds, have blown me hither and thither, in a wayward course, over a deep ocean of anguish, reaching to the very verge of despair. … This has been my life. I have found it worth living, and would gladly live it again if the chance were offered me. (1967, I, 3–4)

How is knowledge possible? The world consists of a complex of logical atoms (such as “little patches of colour”) and their properties. Together these atoms and their properties form the atomic facts which, in turn, are combined to form logically complex objects. What we normally take to be inferred entities (for example, enduring physical objects) are then understood to be logical constructions formed from the immediately given entities of sensation, viz., “sensibilia.” If you are too hot or too cold, you can be perfectly aware of this fact without asking the physicist what heat and cold consist of. … We may give the name ‘data’ to all the things of which we are aware without inference (1959, 23). We can then use these data (or sensibilia or sense data) with which we are directly acquainted to construct the relevant objects of knowledge. To be justified, every indirect knowledge claim must be capable of being derived from more fundamental, direct or intuitive knowledge claims. (SEP)

Definite Descriptions Just as we distinguish three separate senses of “is” (the is of predication, the is of identity, and the is of existence) and exhibit these three senses using three separate logical notations (Px, x=y, and ∃x respectively) we will also discover other ontologically significant distinctions by being made aware of a sentence's correct logical form. (1)The present king of France is bald. ∃x[(Kx & ∀y(Ky → y=x)) & Bx]. By appealing to this analysis, it follows that there is a way to deny (1) without being committed to the existence of a present King of France, namely by accepting that “It is not the case that there exists a present King of France who is bald” is true.

The value of philosophy The value of philosophy is, in fact, to be sought largely in its very uncertainty. The man who has no tincture of philosophy goes through life imprisoned in the prejudices derived from common sense, from the habitual beliefs of his age or his nation, and from convictions which have grown up in his mind without the co-operation or consent of his deliberate reason. To such a man the world tends to become definite, finite, obvious; common objects rouse no questions, and unfamiliar possibilities are contemptuously rejected. As soon as we begin to philosophize, on the contrary, we find, as we saw in our opening chapters, that even the most everyday things lead to problems to which only very incomplete answers can be given. Philosophy, though unable to tell us with certainty what is the true answer to the doubts which it raises, is able to suggest many possibilities which enlarge our thoughts and free them from the tyranny of custom. Thus, while diminishing our feeling of certainty as to what things are, it greatly increases our knowledge as to what they may be; it removes the somewhat arrogant dogmatism of those who have never travelled into the region of liberating doubt, and it keeps alive our sense of wonder by showing familiar things in an unfamiliar aspect

Ludwig Wittgenstein (1889-1951) Tractatus Logico-Philosphicus 1. The world is everything that is the case. 2. What is the case, the fact, is the existence of atomic facts. 3. The logical picture of the facts is the thought. 4. A thought is a proposition with sense. 5. Propositions are truth-functions of elementary propositions. (An elementary proposition is a truth function of itself.) 6. The general form of truth-function is [p, ξ, N(ξ)]. This is the general form of proposition. 7. Whereof one cannot speak, thereof one must be silent.

Early Wittgenstein Tractatus Logico-Philosophicus The picture theory of propositions. My whole task consists in explaining the nature of sentences. A proposition is a picture of reality. When we put a sentence together, we are constructing a model of reality. The model shares its logical form with the state of affairs it refers to. If the model correctly represents reality, the sentence is true.

An important event in the philosophical world (Bertrand Russell) Can we construct a logically perfect language (free of ambiguity and vagueness)? What occurs in our mind when we use language to convey meaning? What is the relation between thoughts, words, and sentences and the realities they refer to? How do sentences convey truth rather than falsehood? What is the relationship between a statement and the symbol which represents it? A logically perfect language has rules of syntax which prevent nonsense, and has single symbols which always have a definite meaning. Language asserts and denies facts- so the structure of the sentence must image the structure of the fact. The sentence must show (not just say) what this structure is.

The misuse of language in philosophy Most propositions and questions that have been written about philosophical matters are not false but senseless….Most questions and propositions of the philosopher result from the fact that we do not understand the logic of our language. They are [like] the question whether the Good is more or less identical than the Beautiful (4.003) Gedanke- The logical picture of a fact which may or may not correspond to the fact pictured. The…record, the musical thought, the score, the waves of sound, all stand to one another in that pictorial internal relation which holds between language and the world. To all of them the logical structure is common.

The nature of thought. A thought is a sentence with a sense. Thinking is not possible without language. Thinking is a kind of language. For a thought too is...a logical picture of a sentence, and therefore it is just a sentence.. A thought describes a possible state of affairs. Philosophy indicates what cannot be said (or thought) by finding what can be said. Names stand for objects. A sentence combines names into a certain configuration (The cat is on the mat.) Outside of logic, everything is accidental.

Later Wittgenstein Rejection of linguistic essences. The meaning of a word is its use in a language. There is no universal property shared by all ‘games’, there is, rather, a complicated network of similarities overlapping and criss-crossing...a set of family resemblances. To understand a sentence, then, one must be a participant in the language-game that displays the use of the sentence.

Task of Philosophy It is of the essence of our investigation that we do not seek to learn anything new by it. We want to understand something that is already in plain view....Our investigation is therefore a grammatical one. Such an investigation sheds light on our problem by clearing misunderstandings away. Misunderstandings concerning the use of words.... Philosophy may in no way interfere with the actual use of language; it can in the end only describe it. What is your aim in philosophy? To show the fly the way out of the fly bottle. Impossibility of a private language.

Wittgensteinian Aphorisms A nothing would serve just as well as a something about which nothing could be said. (PI, 304) Always get rid of the idea of the private object in this way; assume that it constantly changes, but that you do not notice the change because your memory constantly deceives you. (PI, Pt II ix) It is humiliating to have to appear like an empty tube, which is simply inflated by a mind. (Culture and Value, p. 11)

The beetle in the box Wittgenstein invites us to imagine a community in which the individuals each have a box containing a "beetle". "No one can look into anyone else's box, and everyone says he knows what a beetle is only by looking at his beetle."[16] If the "beetle" had a use in the language of these people, it could not be as the name of something - because it is entirely possible that each person had something completely different in their box, or even that the thing in the box constantly changed, or that each box was in fact empty. The content of the box is irrelevant to whatever language game it is used in. By analogy, it does not matter that one cannot experience another's subjective sensations. Unless talk of such subjective experience is learned through public experience the actual content is irrelevant; all we can discuss is what is available in our public language.