Truth

1. Truth Week 03

2. In today’s lecture • Recap of last week’s lecture • The correspondence theory of truth and the coherence theory of truth • Russell’s argument against the coherence theory of truth • Relativism

3. Recap • Inductive and deductive reasoning • Truth-value and basic logical principles

4. 2 theories of truth 1. correspondence theory of truth (真理符合論) 2. the coherence theory of truth (真理融貫論)

5. The correspondence theory • The most important question, as far as the topic of ‘truth’ is concerned, is: How do we determine the truth-value of a belief, a proposition, a theory, etc.?

6. The correspondence theory • The correspondence theory of truth states that a belief or statement is true if there is a corresponding fact and it is false if there is no corresponding fact.

7. The correspondence theory • A proposition or statement is true if there exists a fact corresponding to it. For any proposition p, p is true iff (if and only if) p corresponds to (對應) a fact. • e.g. The statement ‘John had fish for dinner last night’ is true if and only if John really had fish for dinner last night (a fact).

8. The correspondence theory • According to the correspondence theory, truth is the relationship between a belief or proposition and its corresponding (對應的) fact. • But what are facts? How do we know that something is a ‘fact’?

9. The correspondence theory Facts are sometimes defined as ‘what true propositions must correspond to in order to be true’? But is this a useful definition?

10. The correspondence theory Q: What makes a proposition true? A: Correspondence. Q: Correspondence to what? A: Correspondence to a fact. Q: What is a fact? A: A fact is a true proposition. Q: But what makes the proposition true? A: Correspondence…

11. The correspondence theory • The explanation we have just seen is an example of a tautology (同義反覆) i.e. using different words to say the same thing even if the repetition (重複) does not provide clarity. • Thus, it is difficult to have a satisfactory definition of ‘fact’.

12. The correspondence theory Other problems with the correspondence theory of truth: • checking for facts can be extremely time-consuming • the theory does not offer an adequate description of how truth actually works in human minds and social situations

13. Think! How do you determine the truth-value of the following statement? “There’s a green cow behind the door.”

14. Think! To determine the truth-value of the statement “Dogs bark at strangers”, you go to visit a pet shop. As you enter the shop, all the dogs bark at you. Does it mean that the statement “Dogs bark at strangers” is true because you have found a corresponding fact? Why or why not?

15. The coherence theory • The coherence theory states thattruth arises out of the relationship among beliefs and propositions within a ‘belief system’. • A belief system can be understood as all the beliefs that exist in a person’s mind, or the entire body of knowledge and beliefs that exist in a particular society or culture.

16. The coherence theory • Usually, a person or a community (a group, a society, a culture, etc.) works continuously to fit beliefs together into a coherent (貫徹的) belief system. • Thus, the truth or falsehood of a belief or proposition can be examine in the light of other beliefs within the belief system.

17. The coherence theory • As such, abelief or proposition is seen as true if it is consistent with (貫徹一致) other beliefs within the belief system. • Conversely, a belief or proposition is considered not true if it contradicts (抵觸) other beliefs within the belief system.

18. The coherence theory According to the coherence theory, a belief is true when we are able to incorporate (融入) it into a larger and complex system of beliefs. Does the coherence theory provide a better account of truth than the correspondence theory?

19. The coherence theory • The coherence theory of truth states that a belief or proposition is true if it is coherent with other beliefs within a belief system. Truth as ‘coherence’ implies some degree of consistency (一致性) and the absence of contradiction (矛盾). • Russell, however, claims that the coherence theory of truth is mistaken.

20. Russell’s argument Bertrand Russell 羅素 (1872-1970) was a famous British philosopher. He was also a mathematician, logician, writer, and social thinker.

21. Russell’s argument • According to Russell, a belief system may be internally consistent(內部一致) but its contents may still be false because truth is not the same as coherence or internal consistency. • Russell’s argument is that although coherence is a necessary condition (必要條件) for truth, it is not a sufficient condition (充分條件).

22. Russell’s argument • A is the necessary condition of B if the occurrence of B requires the occurrence of A. In other words, without A, there will be no B. • For example, the supply of water is a necessary condition for taking showers. Without water supply, people cannot take showers.

23. Russell’s argument • Water supply is a necessary condition for people taking showers, but it is not a sufficient condition. • Without water supply, no one can take showers. However, even if water supply is available, some people may still choose not to take showers.

24. Russell’s argument • A is the sufficient condition for B if whenever A occurs, B will follow. • For example, whenever there is a shortage (短缺) of a commodity (商品), the price of that commodity will rise. Shortage alone is a sufficient condition for rising prices.

25. Russell’s argument • If a proposition fails to cohere with the rest of our beliefs, we are not justified in believing it. So coherence is a necessary condition for truth. But is it sufficient? • Russell arguesthat coherence alone is not sufficient for truth because a coherent set of beliefs (i.e. a belief system) may not be grounded in reality(以現實為基礎).

26. Russell’s argument • Russell is an advocate (支持者) of the correspondence theory of truth. • ‘Truth’ for Russell is a matter of correspondence between a subjective state of mind (a belief) and an objective state of affairs客觀事實 (a fact).

27. Russell’s argument • For Russell, a ‘belief system’, such as a theory or a religion, is the product of human minds. The content of the belief system may or may not accurately represent outside reality. • A ‘fact’, on the other hand, is an objective state of affairs, some aspect of the external world (外在世界) that is independent of human minds.

28. Russell’s argument • Truth and falsehood, according to Russell, are determined bythe relationshipbetween a belief or propositionand some aspect of the external world or outside reality (i.e. a fact). • Internal coherence is not a sufficient condition for truth. An internally coherent belief system (a theory, a religion, etc.) can still be false.

29. Russell’s argument • A novelist (小說作家), for example, might invent a coherentstory of the past that would perfectly fit into what we know, and yet quite different from the real past. • In addition, there are many different belief systems. Different religions, for example, often contradict (抵觸) one another; and as such, they cannot all be true.

30. Russell’s argument • “It is undesirable to believe a proposition when there is no ground whatever for supposing it true.” ~ Bertrand Russell • Thus, in Russell’s view, we should not believe a proposition to be true unless it is well supported by fact and reason.

31. Think! Do you agree with Russell’s argument? Why or why not? Which theory offers a better account of truth, the correspondence theory or the coherence theory?

32. Read! Read the article ‘Truth and Falsehood’ by Bertrand Russell. It is available for download at the course website: filmandphilosophy.weebly.com

33. Relativism • A judgment is subjective if it is rooted in an individual’s personal beliefs and feelings rather than consideration of relevant data, facts and evidence. • A judgment is objective if all relevant facts, evidence or data are taken into consideration without subjective or personal bias(偏差、偏見).

34. Relativism • The idea of truth as objective is simply that no matter what people believe to be the case, some things will always be true and other things will always be false. • Objective truth, in other words, is independent of the way people think and has nothing to do with anyone’s subjective beliefs or personal opinions.

35. Relativism • Relativism (相對主義) is the view thatreality does not exist apart from a person’s beliefs about it. Therefore, truth is not objective; it is subjective. • Relativists(相對主義者) argue that conceptions of truth are not absolute but are relative to the persons or groups holding them. (absolute = one and the same for everyone)

36. Relativism • Example: The King of Rock ’n Roll, Elvis Presley died of heart attack in 1977. Many of his fans, however, refuse to believe that their idol is dead. They believe that Elvis is still alive – he just went into hiding for some personal reasons.

37. Relativism • If truth is objective, whether Elvis is dead or alive has nothing to do with what we think or what his fans think. If he is dead, he is dead. His death is an objective fact. End of story. • Relativists would say, however, that the statement ‘Elvis is dead’ is not an objective truth as long as different groups of people cannot reach agreement on whether it is true or not.

38. Relativism • Relativists believe that there are no absolute or objective truths – whatis true from one point of view might not be true from another. • Truth is a relative concept, according to relativists, because different individuals, groups, societies, cultures and religions cannot reach agreement on what is true (or false).

39. Relativism • German philosopher Immanuel Kant (康德) disagreed with relativism because he believed that all rational (理性的) human beings usethe same set of basic concepts to make sense of the world. • In Kant’s view, because concepts such as ‘object’, ‘identity’, and ‘causality’ are essential for all human experience and knowledge, it is not possible for truth to be relative.

40. Relativism • Relativists, however, mightsay that Kant underestimated (低估) the differencesin ideas, concepts, and beliefs across societies and cultures. • Relativists may argue, for example, that language differences may cause people of different cultures to have very different experience and perception (感覺、觀感) of reality.

41. Relativism Who is right, Kant or the relativists? Is it true that all truths are relative and subjective?

42. Relativism • On closer analysis, the arguments for relativism can be broken down into a number of ideas or propositions: [1] Different people may have different beliefs – what is true for one group, society, culture, etc. may not be true for another.

43. Relativism [2] Human thought is situated in context(語境、特定處境) –theway we think is inevitably (無可避免地) shaped (被塑造、被導引) or affected by our society, culture, etc. [3] Different groups, societies and cultures have different standards of evidence, reasoning, knowledge and truth.

44. Relativism [4] There is no way to step outside of one’s own belief system and check to see whether one’s beliefs are objectively true. [5] There is no such thing as objective or absolute truth. While most philosophers would agree with [1] and [2], there are strong counterarguments to [3], [4] and [5].

45. Relativism • Counterargument to [3]: Groups, societies and cultures interact (互動) and evolve (進化) and the ones that survive (存活) over time tend to have more and more similar standards of evidence, reasoning, knowledge and truth. Different groups or communitiesare likely to share many common beliefs which can be used as bridges to build consensus(共識).

46. Relativism • Counterargument to [4]: The scientific method allows us to uncover objective facts and thereby enables us to examine the truth of our own beliefs.Some cultures used to believe that the Earth was flat, that the sun orbited the Earth, and that storms were caused by angry gods. Today, we have discovered better, more scientific explanations that are accept across different cultures.

47. Relativism • Counterargument to [5]: By making the assertion that ‘all truth is relative’, the relativist is arguing that the statement ‘There is no absolute truth’ is absolutely true. The statement is self-contradictory (自相矛盾) and thus refutes (推翻、否定) itself.

48. Think! Do you think there is a connection between relativism and the coherence theory of truth?

49. Read! Go the course website, download and read the articles titled ‘Thinking about Relativism’ and ‘Fact versus Faith’. filmandphilosophy.weebly.com

50. Next week