韩国期刊《21世纪马克思主义》第29期

[Abstract] As an expression of the law of causality, the Same Evidence Principle is a basic epistemological principle that informs daily life. Both sceptical problems and the Gettier problem make use of this principle to posit doubt about whether we have certain knowledge or not. The universal validity of the Same Evidence Principle could be demonstrated by the transcendental deduction. The non-universal invalidity of this principle could be demonstrated by applying practical materialism. Using the theory of Marxism's epistemology, we seek here the answer to the sceptical problems and the Gettier problem.

[Keyword] Sceptical problems; Gettier problem; Marxism; Marxist epistemology

1. The Same Evidence Principle: A Widely Used Epistemological Tool

With the meaning of 'same evidence, same result,' the Same Evidence Principle is recognized as a basic epistemological principle within traditional western epistemology. The rationality of this principle is almost unassailable.

In our daily life, the Same Evidence Principle is considered to be the guarantee of justice. Take a court case for example: If all the evidence collected one month ago clearly showed that one noble John Doe is guilty of murder in a murder case, and thus he has been sentenced for his crime by Judge Coke, the same conclusion should be made when the Judge is reviewing the case the next month, before which no new opposing evidence has been found showing that John Doe is not the murderer, and without regard to how Coke is feeling at the moment (perhaps he is worried about the risk of losing his position or even his life). Otherwise, if, based on the same evidence, John Doe had been sentenced as guilty last month but is innocent this month, people would consider the judgment on the case to be unjust.

In the field of science, the Same Evidence Principle guarantees objectivity because of its coherence with the law of causality. That is to say, 'the same antecedent results in the same consequent' or 'the same cause always produces the same result, and the same result always derives from the same cause' (Hume 1997: 178). According to the viewpoint of scientists like Albert Einstein, the implementation of the law of causality is a basic premise of their scientific activities. In a letter to Max Born, Einstein wrote that if he were forced to abandon strict causality, he 'would rather be a cobbler, or even an employee in a gaming house, than a physicist.' (Einstein 2009: 286). And from the viewpoint of the positivists, one of the core tenets of scientific objectivity is testability, because testability subjects all scientific activities to the strict monitoring of experts within the same field.

Scientific activities require scientists to explain their conclusions to their associates in such a way that they can demonstrate them using publicly accepted methods and procedures. The affirmation of a scientific discovery should always rest on the basic premise that the experiment can be repeated and its result be reproduced. The implementation and functions that make up an experiment should not differ under strictly stipulated and controlled conditions and should not vary according to people, time or place. Hence, implementing the principle of 'same evidence, same result' guarantees the objectivity of a socially recognized system for scientific discoveries.

2. The Same Evidence Principle and Sceptical Problems

As discussed above, people usually consider the Same Evidence Principle to be a guarantee of the acquisition of true knowledge. However, another interesting phenomenon is that sceptics also make use of this principle (consciously or unconsciously) to prove that we do not have such true knowledge.

The Affirmation of the Same Evidence Principle Leads to Cartesian Scepticism

In his book of Meditations on First Philosophy, René Descartes shows us that one's perceptual experience can be produced in the state of both waking and sleep; thus, the evidence from perceptual experience cannot distinguish the state of waking from sleep.

How often have I dreamt that I was in these familiar circumstances, that I was dressed, and occupied this place by the fire, when I was lying undressed in bed?… I extend this hand consciously and with express purpose, and I perceive it; the occurrences in sleep are not so distinct as all this.… I perceive so clearly that there exist no certain marks by which the state of waking can ever be distinguished from sleep, that I feel greatly astonished. (Descartes 1984: 13)

However, the evidence for people's cognition seems to be perceptual experience alone. If 'there exist no certain evidence by which the state of waking can ever be distinguished from sleep,' (Descartes 1984: 13) the evidence acquired from sleep and from the state of waking does not seem any different and may be considered the same. And, based on the Same Evidence Principle, we must say either (1) we can have the knowledge by perceptual experience in the state of both waking and sleep or (2) we do not have the knowledge by perceptual experience in both the state of waking and sleep. However, usually we will accept the judgment that 'dreams in sleep are not true' and thus affirm that the knowledge acquired in dreams is not true and that there is no knowledge by perceptual experience. Based on this judgment, we can accept only option (2) from the two options above, whose conclusion is that we do not have knowledge by perceptual experience in either the state of waking or of sleep.

We can also express Cartesian Scepticism in the form of demonstration as follows:

(1.1)

Because dreams are not true,

And dreams produce perceptual experience,

The perceptual experience produced in dreams is not true. (1-1)

(1.2)

Because there is no certain evidence by which the state of waking can ever be distinguished from dreams,

And both the state of waking and dreams produce perceptual experience,

We cannot distinguish the perceptual experience in the state of waking from the one in dreams. (1-2)

(1.3)

Because we cannot distinguish the perceptual experience in the state of waking from the one in dreams, (1-2)

And the perceptual experience can be either true or false,

And the same evidence produces the same result (Same Evidence Principle),

Either the perceptual experience in the state of both waking and dreams is true, or the perceptual experience in the state of both waking and dreams is false. (1-3)

(1.4)

Because the perceptual experience produced in dreams is not true, (1-1)

And either the perceptual experience in the state of both waking and dreams is true, or the perceptual experience in the state of both waking and dreams is false, (1-3)

The perceptual experience in the state of neither waking nor dreams is true. (1-4)

(1.5)

Because knowledge must be true, ①

And the perceptual experience in neither the state of waking nor dreams is true, (1-4)

We do not have knowledge acquired by perceptual experience. (1-5)

Cartesian Scepticism is deeply subversive because its conclusion ('we do not have knowledge acquired by perceptual experience') can directly threaten the whole proud edifice of science, which has perceptual experience as its foundation. Kant considered the lack of closure regarding such sceptical problems as 'a scandal to philosophy'. According to him:

…it still remains a scandal to philosophy and to human reason in general that the existence of things outside us (from which we derive the whole material of knowledge, even for our inner sense) must be accepted merely on faith, and that if anyone thinks good to doubt their existence, we are unable to counter his doubts by any satisfactory proof. (Kant 1958: 34)

The Consideration of the Same Evidence Principle Led to Hume's Scepticism

In David Hume's opinion, the so-called knowledge of cause and effect from experience is actually equal to the reasoning of (Proposition B) 'I predict that an object that seems like ones we have experienced will have the same effects as theirs' from 'I find a certain object always yields certain effects in result' (Proposition A). Obviously, we can see that reasoning from Proposition A to Proposition B makes use of the epistemological principle of 'same evidence, same result'.

In his Treatise of Human Nature, Hume doubts the logic of such reasoning from Proposition A to Proposition B. He points out that reasoning from Proposition A to Proposition B cannot be made obvious by virtue of the reasoning of the connection between concepts – demonstrative reasoning – because the converse of propositions is not contradictory. As he explains:

Since there is no outright contradiction in supposing that the course of nature will change so that an object that seems like ones we have experienced will have different or contrary effects from theirs. Can't I clearly and distinctly conceive that snowy stuff falling from the clouds might taste salty or feel hot? (Hume 1999: 28)

In Hume's opinion, because we cannot arrive at Proposition B from Proposition A by demonstrative reasoning, and there are only two types of reasoning (demonstrative reasoning, based on the connection between concepts, and the reasoning of probability, based on facts), we can now depend only on the reasoning based on facts. Hume demonstrates further that the production of knowledge based on facts beyond perceptual experience (as in deriving Proposition B from perceptual experience such as Proposition A) must follow the relation of cause and effect. In his words:

All reasonings about matters of fact seem to be based on the relation of Cause and Effect, which is the only relation that can take us beyond the evidence of our memory and senses.… When we reason in this way, we suppose that the present fact is connected with the one that we infer from it. If there were nothing to bind the two facts together, the inference of one from the other would be utterly shaky. (Hume 1999: 20)

Obviously, he is describing a vicious circle.

Hume's scepticism shows that the rationality of any attempt to produce knowledge based on facts by reasoning from perceptual experience by virtue of the relation of cause and effect (epagoge) cannot be demonstrated. The impact of Hume's conclusion on the philosophy of empiricism is critical. As Bertrand Russell put it:

Hume's philosophy, whether true or false, represents the bankruptcy of eighteenth-century reasonableness.… It is therefore important to discover whether there is any answer to Hume within the framework of a philosophy that is wholly or mainly empirical. If not, there is no intellectual difference between sanity and insanity. The lunatic who believes that he is a poached egg is to be condemned solely on the ground that he is in a minority… (Popper 2003: 6)

3. The Same Evidence Principle and the Gettier Problem

The definition of knowledge according to traditional western epistemology is that knowledge consists of three elements: belief, truth and justification. This means that if (1) The Proposition P is true; and (2) S believes that P is true; then (3) S is justified in believing that P is true. Hence, if and only if all three conditions are fulfilled, can we say that 'S knows that P is true.'

It is said that this definition of knowledge dates back to ancient Greece. In the book Meno, Socrates pointed out that knowledge differs from opinion but did not provide an answer as to how to distinguish them. However, in the later work Theaetetus, his student Plato revisited this question and answered it. Furthermore, Plato attempted to 'bring the many sorts of knowledge under one definition.' (Plato 1961: 853) This is the 'tripartite definition of knowledge,' or 'Plato's definition,' as defined in current western literature on epistemology (Chisholm 1982). As for its classical influence, this definition is considered to be 'The Traditional Analysis of Knowledge' under propositional conditions. (Feldman 2003: 8)

In his short paper published in Analysis in 1963, Edmund Gettier presented two effective counter-examples, attempting to demonstrate that the traditional analysis of knowledge is insufficient. Case I of his presentation is as follows:

Suppose that Smith and Jones have applied for a certain job. And suppose that Smith has strong evidence for the following conjunctive proposition: (d) Jones is the man who will get the job, and Jones has ten coins in his pocket.

Smith's evidence for (d) might be that the president of the company assured him that Jones would in the end be selected, and that he, Smith, had counted the coins in Jones's pocket ten minutes ago. Proposition (d) entails: (e) The man who will get the job has ten coins in his pocket.

Let us suppose that Smith sees the entailment from (d) to (e), and accepts (e) on the grounds of (d), for which he has strong evidence. In this case, Smith is clearly justified in believing that (e) is true.

But imagine, further, that unknown to Smith, he himself, not Jones, will get the job. And, also, unknown to Smith, he himself has ten coins in his pocket. Proposition (e) is then true, though proposition (d), from which Smith inferred (e), is false. In our example, then, all of the following are true: (i) (e) is true, (ii) Smith believes that (e) is true, and (iii) Smith is justified in believing that (e) is true. But it is equally clear that Smith does not KNOW that (e) is true; for (e) is true in virtue of the number of coins in Smith's pocket, while Smith does not know how many coins are in Smith's pocket, and bases his belief in (e) on a count of the coins in Jones's pocket, whom he falsely believes to be the man who will get the job. (Gettier 1963: 121–23)

By presenting such counter-examples, Gettier concluded as follows: 'These two examples show that definition (a) does not state a sufficient condition for someone's knowing a given proposition.' Gettier's doubt about traditional analysis is overwhelming, and indeed, the traditional viewpoint for knowledge 'was shattered' (Plantinga 1993: 6). Further, 'What the Gettier problem really shows is what a perverse concept knowledge is.' (Pollock and Cruz 1999: 15) The epistemological problem triggered by the inference from Gettier's counter-examples is usually called the Gettier problem.

In Richard Feldman's opinion, Gettier's counter-examples make use of the Same Evidence Principle; thus, the substance of the Gettier problem is whether or not we must follow this principle. In order to show that the existence of the counter-examples is necessary and rational, Feldman advocated an improvement of the counter-examples to remove the interference imparted by the linguistic expressions.

Feldman posited the following example: Suppose that, sitting on a running car, I see what looks exactly like a sheep, so I justifiably believe (A1): That animal in the field is a sheep. Obviously, from (A1), I can reason that: (B1) There is a sheep in the field. However, what I actually see is just a piece of timber that resembles a sheep, although there is a real sheep elsewhere in the field. Hence, in my process of cognition: (1) B1 is a true belief; (2) I believe B1; and (3) I am justified in believing B1 (although it is demonstrated from a wrong premise: A1). The question then is: Do I know B1? (Or: Do I have knowledge of B1?)

In this example of Feldman's, Belief A1 contains Belief B1. According to this connection, 'I' reason a correct conclusion from a wrong belief and thus have a 'justified true belief', although actually 'I' still do not know this belief. In the example, it is the obvious effect of the Same Evidence Principle that leads us into the trap of scepticism. It is so because there are actually two possibilities from my evidence A1 ('That animal in the field is a sheep'), true or false, but I cannot distinguish either of them, and thus my conclusion of B1 should be the same. In other words, in both conditions, either I think I know B1 or I don't think I know B1, which leads to the scepticism.

By now, most philosophers in epistemology consider that the 'Gettier problem is a core problem of epistemology, which poses an obvious obstacle for the analysis of knowledge.' (Jiaming 2000: 14) It is even said that it 'has fundamentally changed the characteristics of the contemporary epistemology'. (Shope 1983: 14)

4. The Reasoning Behind the Universal Validity of the Same Evidence Principle

By going through the analysis of several sorts of scepticism above, we can clearly see that as a presupposition, the Same Evidence Principle is the basis for the occurrence of scepticism. Therefore, if we want to jump out of the traps of scepticism, it is very important for us to perform a further analysis of the Same Evidence Principle's rationality and range of effects.

Based on our intuition, it is difficult to overturn the Same Evidence Principle indeed, because, to some degree, its position as a foundation of traditional epistemology is similar to the one held by the law of identity in logic. For instance: For S, the content of a certain object under two different conditions is the same; and then for S, the object either is A or is not A. It cannot be both A and non-A, or it will violate the law of identity in logic. Now, let us replace the object with a certain proposition. Then, from their similarity, we can reason as follows: For S, if the evidences for believing a certain proposition to be true under two conditions are the same, S should believe this proposition to be either true or false under these two conditions. In other words, the same evidence will lead to the same result.

From the viewpoint of rationality, as an expression of the law of causality, the Same Evidence Principle itself does not contain any element of experience; thus, it belongs to a pure form of thought, which should be objective.

In Kant's opinion, the necessity of knowledge is guaranteed by the internal connections among various ranges of pure thought-forms. From its occurrence, knowledge is a subjective concept, but if it is effective for all cognitive subjects, the universal validity of such a subjective concept must be its objectiveness.

Kant affirms that the law of causality belongs to the a priori categories of cognition. And in reasoning about the necessary existence of a priori categories, Kant makes use of the form of transcendental deduction. For example:

…even though we cannot assume that metaphysics as science is actual, we can confidently say that some pure synthetic cognition a priori is actual and given, namely, pure mathematics and pure natural science; for both contain propositions that are fully acknowledged, some as apodictically certain through bare reason, some from universal agreement with experience (though these are still recognized as independent of experience). We have therefore some at least uncontested synthetic cognition a priori, and we do not need to ask whether it is possible (for it is actual), but only: how it is possible, in order to be able to derive, from the principle of the possibility of the given cognition, the possibility of all other synthetic cognition a priori. (Kant 1997: 31)

The passage above shows that the model of Kant's transcendental deduction works like this: Firstly, consider the conditions of the possibility of a phenomenon Y without controversy, and discover a contentious object X as a condition that makes Y possible; then conclude that 'X exists' or 'X is actual'. (Xiangdong 2006: 188) Therefore, the transcendental deduction has the following structure:

(1) Y is possible only if X is actual.

(2) Y is substantial.

(3) Hence, X must be actual.

In this deduction, Kant concludes that pure mathematics and pure natural science are obviously of indubitable dependability, which means that they are dependable for everybody, because both of them result from rationality. And, in the view of Kant, pure mathematics and pure natural science are obviously substantial (Y is substantial). Further, pure mathematics and pure natural science are possible only if the 'a priori categories' are actual (Y is possible only if X is actual). Therefore, the 'a priori categories' must be actual.

By way of the 'transcendental deduction', Kant considered that he could successfully overcome Hume's scepticism:

I openly confess, the suggestion of David Hume was the very thing, which many years ago first interrupted my dogmatic slumber.… I was far from following him in the conclusions.… I therefore first tried whether Hume's objection could not be put into a general form, and soon found that the concept of the connexion of cause and effect was by no means the only idea by which the understanding thinks the connexion of things a priori, but rather that metaphysics consists altogether of such connexions.… I proceeded to the deduction of these concepts, which I was now certain were not deduced from experience, as Hume had apprehended, but sprang from the pure understanding. (Kant 1997: 10)

We can see that in Kant's opinion, the concept of the connexion of cause and effect is a priori, which is the premise that makes possible our cognition. And thus, unlike sceptics, we do not need to question 'whether it is possible' but 'how it can be possible'. This is a clever solution, but it raises another question: As 'a priori categories' is produced from ideas, it means that we can only recognize the representation of the things to us, instead of knowing them by their essentials.

5. The Premise of the Universal Validity of the Same Evidence Principle

As discussed above, as an expression of the law of causality, the Same Evidence Principle itself does not consist of any experiential element but is a pure form of thought. Therefore, in Kant's opinion, it derives from 'pure understanding' undergirded by a universal necessity.

However, we should note that such 'transcendental deductions' hypothesize the existence of 'abstract rational man'. And this hypothesis, in turn, acknowledges or assumes the competency of everybody as the subject of cognition. The hypothesis that every common person has the same competency of rationality has become the foundation of the concept of the subjectivity of man in cognition. In his book Discourse On Method, Descartes pointed out that:

Good sense is, of all things among men, the most equally distributed; … the conviction is rather to be held as testifying that the power of judging aright and of distinguishing truth from error, which is properly what is called good sense or reason, is by nature equal in all men; and that the diversity of our opinions, consequently, does not arise from some being endowed with a larger share of reason than others, but solely from this, that we conduct our thoughts along different ways, and do not fix our attention on the same objects. (Institute of Foreign Philosophy 1975: 362)

Kant considered that objectivity of knowledge consists in the fact that knowledge is universally valid for everybody:

Therefore objective validity and necessary universality (for everybody) are equivalent terms … yet when we consider a judgment as universal, and also necessary, we understand it to have objective validity. (Kant 1997: 64)

Therefore, as D. W. Hamlyn said, 'Kant's criterion of objectivity is the criterion of intersubjectivity – validity for all men.' (Hamlyn 1987: 65)

Descartes and Kant represent the typical viewpoints and concepts of most modern philosophers' theories. In their opinion, the subject of cognition is the capital 'I' – we, or every individual ego. The real knowledge acquired by people is not personal but endued with some certain universality and generality.

However, the epistemology of modern philosophy based on the capital abstract 'I' as the subject of cognition must result in the ignorance of the human's life will. As Henri Bergson pointed out, 'The characteristic of intelligence is that it's naturally unable to grasp life.' In his book Time and Free Will, Bergson remarked:

But the principle of causality, in so far as it is supposed to bind the future to the present, could never take the form of a necessary principle; for the successive moments of real time are not bound up with one another, and no effort of logic will succeed in proving that what has been will be or will continue to be, that the same antecedents will always give rise to identical consequents. (Bergson 2007: 155,17)

6. Deducing the Non-universal Validity of the Same Evidence Principle

In the authors' opinion, by making use of the practical materialism from Marxist theory, we can discover that the Same Evidence Principle is not universally valid.

Firstly, we should see that, as for the law of identity, the Same Evidence Principle is a form of logic whose characteristic is to abstract the subject of cognition to make a prototypical 'Man' with a capital M, separated from all social and historical context. However, Marxist epistemology denies the existence of such a subject, because in different analytical contexts, 'Man' will always be embodied within a specific cultural context. In the study of political science, 'Man' must be collated and stipulated within the category of 'class'. And when considering gender differences, a 'Man' must be identified by the dual genders of 'male' or 'female'. Therefore, the question that is the subject of cognition has become a proposition to be confirmed within the visual field of deconstruction.

Marxist epistemology affirms that the foundation and source of human cognitive activity is social practice; thus, the target of knowledge must lead to a certain group in real life: 'Its premises are men, not in any fantastic isolation and rigidity, but in their actual, empirically perceptible process of development under definite conditions.' (Marx and Engels 2003: 17)

Therefore, we can often see in real life examples of 'same evidence' without 'same result'. Here we can take Case 1 of Gettier's counter-examples as a demonstration:

Smith's belief e (the man who will get the job has ten coins in his pocket) is deduced from another belief, d (Jones is the man who will get the job, and Jones has ten coins in his pocket). If d is true, Smith has the knowledge of e, and if d is false, Smith does not have the knowledge of e. The confusion created by the Gettier problem is that Smith's evidence about d (d-1 and d-2) is the same whether d is true or false; therefore, e as the deduction of d is either true or false in both conditions. Once it is difficult to tell true from false, we cannot exactly affirm that we know anything, which leads us into the trap of scepticism.

However, if we do not limit the subject of cognitive activity to Smith but extend it to a whole group, the situation becomes rather different. For example, let's include other people in the office, e.g., the boss Andre and the accountant Mark, to make up a cognitive group together with Jones and Smith. In that case, Evidence d-1 (Jones is the man who will get the job) and d-2 (Jones has ten coins in his pocket) forming Smith's belief d will not form the same joint belief with the boss Andre, because the latter knows that Evidence d-1 is false and thus will not deduce belief e from d. In other words, the same evidence of d-1 and d-2 does not produce the same result for different persons. In this way, Gettier's counter-examples will not be effective and will not lead to scepticism.

Next, we should notice that the so-called universal validity of the Same Evidence Principle as an expression of the law of causality embodies only an ideology in a certain historic period rather than an 'eternal truth'.

So why would people like to endow their thoughts with the form of universality? In Marx's opinion:

For each new class which puts itself in the place of one ruling before it, is compelled, merely in order to carry through its aim, to represent its interest as the common interest of all the members of society, that is, expressed in ideal form: it has to give its ideas the form of universality, and represent them as the only rational, universally valid ones. (Marx and Engels 2003: 44)

The famous contemporary physicist Ilya Prigogine questioned why we must follow the law of full causality in scientific activities. Why do scientists pursue the objective knowledge of 'universal validity'? Such questions embody the characteristics of the times:

How can we reach certainty? This question is the core of Descartes' writings. In his inspiring book of Cosmopolis, Stephen Toulmin tries to explain the background for Descartes' quest for certainty. He describes the miserable scenes in the 17th century, a time of political instability and the religious wars between Catholic and Christian for doctrinal arguments. It is in such a time of conflicts that Descartes started his quest for certainty – a certainty that all human beings could share, irrespective of religion.… Descartes' programme has found concrete expression in Newton's work which provided the model for physics for over 300 years. For Einstein, science was a means of avoiding the turmoil of everyday existence.… Einstein's physics intuition can be considered as the supreme achievement of human rationality's transcendence over the world of violence, which divides the objective knowledge from uncertainty and the subjective category. (Prigogine 1998: 149)

With a viewpoint akin to the Marxists', Prigogine reasoned that contemporary science is in a state of alienation, the price of which is to make people lose their free will:

Science is originated from the brave affirmation of the power of rationality, but it seems to alienate finally, to be a denial of all the things that endow meanings to human life. (Prigogine 1998: 149)

The Marxist philosopher Alfred Sohn-Rethel considered the prejudice of ideology to be manifest in the objective concepts of the positivists. He believed that the concept of pure understanding originated in ancient Greece, around 600 B.C., and that this concept was a reflection of the financial economy, in whose structure commodities were already endowed with the mission of exchange beyond mere use. In the same way, Sohn-Rethel opined, just as right after its appearance Galileo's concept of inertia became the foundation of Newton's theory of physics, so, too, the birth of capitalism made the eternal motion of money a necessity. Also based on this viewpoint, the basic structure and range of contemporary science reflect the alienated relation of commodities to their users. Therefore, according to Sohn-Rethel, the widely accepted and most objective form of science is actually an expression of alienated ideology. (Sohn-Rethel 1975: 101)

7. Marxism's Answer to Sceptical Problems and the Gettier Problem

By making use of the theory of practical materialism, we can see that the fundamental mistake (albeit in different forms) of the sceptical problems set forth above is their hypothesis of an abstract rational man. If we instead consider knowledge to be a product of practical human activities based on real life and 'do not explain practice from the idea but explain the formation of ideas from material practice' (Marx and Engels 2003: 36), it will leave us with no doubt that the sceptical problems are false propositions.

As Kant said, 'Instead of elsewhere, Skepticism derives right from the complete disappointment by the dissatisfaction of the most important pursuit of rationality.' (Kant 1997: 29) Then what is rationality? Bertrand Russell used to define human rationality as 'the habit of taking account of all relevant evidence in arriving at a belief'. (Russell 1960: 25) The human inclination towards rationality is intensive and persistent, even at the risk of trapping oneself into the state of embarrassment for pursuing it.

The essence of scepticism is such a spirit of rationality that persistently asks for reasons and evidence. The consequence of Descartes' scepticism is the requirement of holding knowledge to a high standard: in his view, a belief is knowledge if and only if its demonstration disproves all scepticism, including the most exaggerated. And the profound question raised by Hume's scepticism is: What is the foundation for the universal validity of knowledge, especially that acquired from inductive experience?

In our opinion, the requirements of such sceptical problems are alike: Unless you point out what will absolutely not be false, everything can be 'scepticized'. These requirements presuppose the obvious existence of an 'abstract rational man' as the subject of cognition that transcends all historical conditions. And so-called objective knowledge is for just such a capital M, abstract 'Man'.

However, in Marxist theory, such a man is just a creature 'in any fantastic isolation and fixity' (Marx and Engels 1998: 43) instead of a man of his own will. Let us consider how, in real life, the consciousness of men and their sensibilities differ from each other and are in continuous change and development. How can it be possible that there is a form of thought remaining unchanged and influential on everybody? Take the concept of the connexion of cause and effect, for example: How can the perceptions of adults and children, healthy people and blind men, be completely the same? Suppose that, if a man is born blind, his perception of time and space will be quite different from that of common people. For such a man, what is front and what is rear? How about the concept of 'same antecedent, same consequent'? Obviously, a blind man's mode of perception is apt to be quite different from ours. For the same reason, the perceptions of children and adults are not the same at all. And that is a common phenomenon in our life. Therefore, Kant's so-called transcendental intelligence, with its characteristic of universal validity, does not actually exist.

We can likewise see how different civilizations have different ways of perceiving the specific meaning of cause and effect. Take medical science, for example. As we know, western medical science usually focuses on 'disease searching and elimination', with the principle of the 'same treatment for the same diseases'. Its theory affirms that the same disease must have the same essential cause and thus should be dealt with using the same treatment. For traditional Chinese medical science, in contrast, the characteristic of 'body function promotion' (to activate and promote the potential of the body's functions, especially the disease defense system) advocates 'different treatments for diseases of the same symptoms' (Guangshen 2006). In the Chinese way of thinking, despite manifesting the same symptoms, the same diseases should be dealt with using different treatments according to time, location and patient, as well as variations in the development and changes in the disease course, treatment and the body's recovery. As the chapter 'A Discourse on Operations of the Five Elements' in the book Basic Questions in Huangdi's Orthodox Classic describes:

The Qi in the Northwest is dissipated and chilly while the Qi in the Southeast is assembling and warm, and this is a metaphor of the rationale of different treatment for the same disease. (Yi 2010: 197)

Therefore, there is nothing like a universally valid human intelligence that transcends all historical elements, including language, race, gender, religion, etc. Scepticism takes 'abstract rational man' as the object for answering the question 'How can absolutely objective and indubitable knowledge be possible?'. However, such a question is an obviously false proposition in the field of practice.

Furthermore, we should note that scepticism overemphasizes the spirit of rationality while ignoring or denying the function of human intuition in the process of cognition. Descartes' scepticism considers that people cannot distinguish truth from dreams through rationality and thus concludes that 'we don't have knowledge from perceptual experience'. However, is rationality the only way for people to know themselves and the external world? In fact, we find that in real life, everybody has the capacity to distinguish truth from dreams. For example, the biggest difference between human and golem is that a human being can clearly realize that his or her life's will (one could can call it 'stream of consciousness') is vanishing little by little at the end of life, and thus know that his or her life at the moment is not illusory but true. Moreover, when a man is in a fight to the death with others and facing great risk in his dream, he will soon rouse himself from this nightmare and understand what is true and what is illusory. All these examples demonstrate the absolute existence of a life will and intuition by which a man can recognize himself and the external world.

Therefore, if we count human life will as an influential element in the process of cognition, the visual field of practice is a necessary standard in the discovery of knowledge. By making use of Marxist epistemology to review Gettier's counter-examples, we easily find the root of contemporary epistemology's embarrassment in the trap of the Gettier problem. Its embarrassment results from most philosophers raising the questions of pure argument by thinking outside of practice instead of sticking to it. The typical course of their thinking is to treat the Same Evidence Principle in fantastic isolation and rigidity as a 'transcendent' rule of universal validity, but outside the context of social practice. Actually, we can easily find in our practice that 'same evidence' does not always produce the 'same result' and that this can occur in the cognition of both groups and individuals (as demonstrated in Part 6).

Let's revisit Feldman's sheep in the field for an example. According to the shape, color and size of the sheep out of the window of the car, 'I' form such a belief A1: That animal in the field is a sheep. If my practice is to teach children how to recognize a sheep, the 'shape, color and size' are the evidence of a 'sheep', and Belief A1 will be demonstrated as true. However, if my practice is to evaluate this sheep, and if I fail to distinguish the true sheep from the false one, the concepts of 'shape, color, and size' will not become evidence of this 'sheep', and thus A1 will have been demonstrated as a true belief. In this example, for the same subject of cognition – 'I', 'same evidence' does not bring 'same results', which violates the Same Evidence Principle; but obviously, both conclusions are rational and acceptable in certain practical contexts.

Moreover, if our epistemology accepts the point that in practical situations with different aims, 'same evidence' can produce 'different results', Hume's scepticism will be in ruins. After all, his scepticism questions the foundation of the universal validity of knowledge – especially deduced from perceptual experience – and our answer is that there is no foundation for the universal validity of knowledge. Therefore, the validity or invalidity of epistemological principles (including the deduction principle and Same Evidence Principle) must be analysed and decided upon within the context of certain practices. Thus, the evidence of knowledge is meaningful only within the specific contexts of real life.

8. Conclusion

According to the above analysis, we can see that there are two fields of vision on which to reframe the philosophy of knowledge:

(1) The first one is the field of rationality. Its characteristic is to achieve the whole abstract grasp of the concept of knowledge through the analysis of structural elements of knowledge (e.g., demonstration, truth, belief). This way of thinking does not analyse the characteristics of the subject of cognition but presupposes it to be an abstract representative of 'everybody', according to the proposition that everybody has transcendental intelligence posited a priori by theory. However, the conclusion of scepticism's questioning of knowledge with the spirit of rationality demonstrates that rationality alone is not sufficient to answer the question of 'why knowledge is possible'.

(2) The other one is the field of practice. Its characteristic is to achieve the specific and lively grasp of the concept of knowledge through the analysis of historical elements (e.g., class, race, religion, language and cultural background) of the subject of cognition. This field of vision emphasizes that people in real life have their life will. Its point is to disprove scepticism and conclude that the foundation and origin of knowledge lie within practice and that knowledge is not properly understood abstractly, outside the context of practice.

Generally speaking, Marxist epistemology emphasizes the intersubjectivity of knowledge, which is formed in practical circumstances: (1) Human practice is the process of social and historical activity; thus, the viewpoint of traditional western epistemology that knowledge can be acquired by single, independent individuals is doubtful. (2) Knowledge is produced in human practice to improve the world; thus, all knowledge must be considered to derive from certain forms of production instead of a certain transcendental structure of pure understanding.

By applying Marxist epistemology as above, in the author's opinion, the reason why sceptical problems, and the Gettier problem in particular, have become difficult problems of traditional epistemology is because both of them make use of the Same Evidence Principle as a transcendental rule while allowing the disengagement of knowledge from practice. Also, scholars of epistemology have not rethought this basic presupposition when dealing with these problems and thus have failed in their attempt to solve them. The authors deeply believe that by analysing these problems using Marxist epistemological theory, and by introducing the two elements of 'practice' and 'intersubjectivity', there will be a new way of thinking about the solution to the sceptical problems and the Gettier problem. This, in turn, will lead to a fresh understanding and definition of the concept of knowledge.

[This work was supported by The Youth Foundation Project for Humanities and Social Sciences Research of Ministry of Education of China 2011 [Project Approval No. 11YJC720030].]

参考文献:

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①In traditional western epistemology, knowledge is defined as “true judgment with an account” (also known as Plato’s definition). The latter part of this essay will discuss this definition of knowledge.

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（Author:Lv Xulong (1973– ) is a lecturer at the School of Marxism of Shanghai Jiaotong University. He is also an assistant researcher at the Research Center of Epistemology and Cognitive Science of Xiamen University and Doctor of Philosophy. ）