Assessing exosomes production and autophagy in HeLa cells

2.4 Results and Discussion

2.4.3 Assessing exosomes production and autophagy in HeLa cells

While the correspondence theory of truth has a long history, and was known in its essential features in antiquity, the term correspondence theory has gained popularity primarily through the

writings of Bertrand Russell. The correspondence theory of truth holds that truth consists in some form of correspondence between a belief or a sentence and a fact or a state of affairs.

There are many examples of the correspondence theory of truth, but we will examine three formulations which demonstrate the salient features of the theory. We will discuss the positions of Aristotle, G. E. Moore, and Alfred Tarski.

Aristotle

Exposition. Aristotle gives a definition of truth that is, on examination, clear and simple: “To say of what is, that it is not, or of what is not, that it is, is false; while to say of what is, that it is, and of what is not, that it is not, is true.”

According to Aristotle, substances are characterized by the fact that they can at differing times have opposite qualities. But do statements or opinions fall under this criterion? The statement, “It is raining out” may appear to be true today and false tomorrow. But Aristotle rejects this suggestion, for he thinks this conclusion rests on a misunderstanding. In this example there is no genuine alteration in the statement itself, but in the fact outside (it is raining), by which the statement’s truth or falsity is measured. “For it is by the facts of the case, by their being or not being so, that a statement is called true or false.”

Aristotle speaks of the facts as a kind of causation. The facts cause the truth of the statement by asserting that fact. It has been noted that what Aristotle calls a cause, many contemporary philosophers would be more likely to call a criterion.

Criticisms. What we might call the Platonic-Aristotelian correspondence theory of truth had not long been formulated when a problem or criticism was brought against the view. It was suggested by Eubulides, a member of the school of Megara. (This school seems to have been in conflict with a good many of the basic Platonic-Aristotelian positions.) Eubulides’s objection to the correspondence theory has been called the “liar paradox.” Eubulides asks his hearers to consider a man who says, “I am lying” or “I am now uttering a falsehood.”

The problem with this statement should be obvious. The utterance is true if it is false, and false if it is true. Thus, in at least one case, the correspondence theory of truth seems to result in an utterance meaning its opposite. Furthermore, because of the Aristotelian

dependence on fact for the truth or falsehood of a proposition, we have at least an apparent problem. The related matter of fact is the truth or falsity of the statement. This “paradox of the liar” has been much debated both in ancient and contemporary philosophy, and it has been assumed that any adequate theory of truth must give a satisfactory answer to this problem.

One possible answer to the paradox is to insist that the claim “I am lying” is

self-destructive or self-defeating and, therefore, is not a truth claim at all. To use mathematical language, sentences like this constitute the null set. (Another answer to this problem will be suggested by the work of Tarski, below.)

G. E. Moore

One may choose either Bertrand Russell (1872–1970) or G. E. Moore (1873–1958) as a representative of the modern formulators and defenders of the correspondence theory. We have chosen Moore because his position is easier for the beginning student to understand.

Moore’s early views. Moore and Russell were lifelong friends and colleagues at

Cambridge, forging their philosophical positions against their earlier training in idealism.

Moore’s early views on truth are contained in a series of lectures which he gave in 1910–11.

According to Moore, truth and falsity are properties of what he called propositions. A proposition is identified with the meaning of an indicative sentence. In hearing and

understanding a spoken sentence and in seeing and understanding a written sentence, something is apprehended by us which is more than the mere sentence. While the act of apprehension is the same in all cases, what is apprehended is different in various sentences.

Acts of belief and sentences can only be called true or false in a secondary sense, but it is a proposition that is in fact the bearer of truth or falsity.

Moore’s later position. Moore returned to the questions of truth and falsity in his later writings, although he modified his views somewhat. In his later work he talked about beliefs rather than propositions. He defined the difference between a true and a false belief as follows: When a belief is true, that which is believed is a fact; when a belief is false, that which is believed is not a fact.

Moore also asserted that there are no such things as propositions. Moore expressly said that truth does not consist of three parts: a believer, a belief, and some other thing called a proposition. In his most developed treatment, Moore argued that the truth of a belief consists in a relationship between a person and a fact. Thus in Moore’s more mature thinking facts replaced propositions. He explicitly said that the relationship between the belief and the fact is one of correspondence. Facts exist in the same sense that chairs and tables exist.

There is one problem that Moore does not address. It has to do with false beliefs and the existence of false facts. Russell and others were much concerned with this issue, and clearly denied that false facts exist. If they did exist, false facts would clutter up the ontology of the world. Rather, false beliefs fail to correspond to anything. For instance, when we falsely believe that the moon is made of green cheese, our belief corresponds to nothing.

Alfred Tarski

The twentieth-century Polish logician, Alfred Tarski, has picked up and amplified the medieval idea of “true” as a straightforward adjective of a straightforward object in a sentence.

His treatment of the topic is considered by most philosophers as one of the classics of modern logic. While his concern is primarily with the idealized language of logic, some argue that what Tarski says is applicable (with some minor revisions) to ordinary language.

According to Tarski, truth is a property of sentences. A sentence is true or false only as it is a part of a particular language. (The medieval scholastic theologians and philosophers were sensitive to this point as well.) Take for example the sentence, “Man is a car.” This sentence is only true or false in relation to some concrete language, and would be true in a language where the word car meant what we now mean by mammal.

Moreover, Tarski denies that a sentence which asserts that sentence S is a true sentence of L (a particular language), can itself be a sentence of L. Such a sentence would belong to what Tarski call a metalanguage, a second-order language in which talk about the first-order language is possible. By so doing Tarski has offered another possible resolution of the liar paradox, since any sentences asserting either the truth or falsity of sentences of L would not belong to L but to a meta-language.

Finally, Tarski defines truth in terms of correspondence. The sentence, “Snow is white”

is true if and only if snow is indeed white. Truth then is a property of sentences, and involves a relationship between a sentence and reality.

Conclusion

In this chapter we have examined four principal theories of truth: the coherence theory of truth; the pragmatic theory of truth; the performative theory of truth; and the correspondence theory of truth. We have argued that the first three theories of truth are inadequate, that the correspondence theory alone is sufficient. As Christians, we cannot accept any theory of truth which results in either relativism or agnosticism. The Bible clearly declares that man can know the truth, and will be held responsible for such knowledge.

Assessing exosomes production and autophagy in HeLa cells

2.4 Results and Discussion

2.4.3 Assessing exosomes production and autophagy in HeLa cells

Conclusion

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