Abstract

Every inquiry into skepticism in the Middle Ages aims at seeking the missing link that would allow the understanding of how we changed from the ancient conception of skepticism as a way of life (living without belief) to a modern conception of skepticism as the general critique of knowledge. The medieval reception of the ancient mode of skepticism and the transformations they made after its reception allow us to understand this evolution. Thus, the Middle Ages occupy a nodal place in the history of skepticism.

Strictly speaking, there is no skeptical school in the Middle Ages insofar as no one, except John of Salisbury, explicitly claimed to be a skeptic. Medieval epistemology on the other hand accords a place of growing importance to the question of skepticism, ultimately finding incontrovertible the examination and refutation of skeptical arguments. In a way, skepticism in the Middle Ages is primarily a construction lacking a historical foundation; a set of arguments against the possibility of knowledge and a test for all theories of knowledge. Nonetheless, the consideration of these arguments, conjoined with the development of a set of theories of knowledge attuned to the fallibility of human reason and to the problem of induction drove, at the end of the Middle Ages, some philosophers to develop theories of knowledge that produce skeptical effects, limiting the hold of our capacity for knowledge (e. g., Nicolas of Autrecourt, William Crathorn, Robert Holcot). It is in this sense that we can speak of a medieval form of skepticism proper in the fourteenth century.

In order to understand how the medieval skeptical vision was elaborated, we must examine the medieval reception of ancient skepticism. If Sextus Empiricus’ Outlines of Pyrrhonism was available in Latin near the end of the Middle Ages, it is not possible to tell today if the text had any readers. In the same fashion, Cicero, whose texts were more widely circulated, could have influenced John of Salisbury (who does not seem to know of the Academics, however) and Henry of Gent, but his real influence remains quite minimal. Indeed, the construction of the image of skepticism as that which denies the possibility of knowledge stems from the conjunction of the Augustinian influence and the rediscovery of Pre-Socratic (Democritus, Protagoras, Heraclitus) arguments via Aristotle. Presenting neo-Academic doctrines in a synthetic manner in Against the Academicians II, 11, Augustine shows what we can call the logical structure of skepticism. The point of departure and the crux of the Academic position is that nothing can be known. Augustine draws the conclusion, typically skeptical according to him: the sage must suspend assent. This suspension of assent would be taken as a general doubt in the Middle Ages. Augustine thus emphasizes the fundamental status of the thesis according to which nothing can be known (that is to say an object of scientia, or to be known with certainty). This thesis is proved by the Academics by showing that it is impossible to find a perception that is an evident criterion of truth. Augustine goes on to elaborate a typology of skeptical arguments: (1) disagreement among people (i. e., relativity of knowledge); (2) the fallibility of the senses; (3) dreams and madness, and, finally; (4) paralogisms and sophisms. (1) permits the emphasis that there are no evident and universal criteria for truth, (2) and (3) that the sources of knowledge are not reliable, and (4) that error is found just as much at the level of reasoning as it is in the testimony of the senses. This thus frames the portrait of skepticism as that which denies the possibility of knowledge due to the impossibility of distinguishing truth from falsity since uncertainty is found just as much in objects as it is in the knower. The model of skepticism inherited in the Middle

Ages is taken from here. Faced with this kind of skepticism, there is a complementary double attitude: skepticism must then be refuted by showing that there is evident knowledge (the cogito, mathematics, revealed truths). Once refuted, however, it becomes legitimate to make a limited use of skepticism as a test to distinguish true and false knowledge. Use and refutation: a schema that we find throughout the Middle Ages. If the Augustinian model determines the whole of the medieval conception of skepticism, it will be enriched, however, by the superposition of different traditions. The first enrichment stems from the rediscovery of the pre-Socratic tradition through Aristotle, beginning in the twelfth century. Two sets of texts are important. One, stemming from the Posterior Analytics, and book II of the Metaphysics, drive the questions of what we must demonstrate and, more generally, justify. It is in this context that the medievals examine the problem of skepticism: can we know anything? Can we apprehend truth? The second set of texts is made up of book IV of the Metaphysics. The analyses of Heraclitean, Protagorean, and Democritean doctrines give rise to the examination of a host of arguments thought to be skeptical. According to Aristotle, upholding that all that is apparent is true makes it no longer able to distinguish the true from the false. More often, the reading of these texts allows giving an ontological basis to skeptical doctrines: it is because they hold, like Heraclitus, that all things are in flux, and because they deny the principle of noncontradiction that the Academics hold that we cannot know anything. The second enrichment is properly medieval and results from reflection, mostly from Duns Scotus, on the radical contingence of the created and on the omnipotence of the Divine. The basic idea is to not set a limit to Divine freedom. From here, we must emphasize that the created world is not simply the actualization of Divine Ideas, according to logical necessity, but that the status of this world is contingent and that it could be otherwise. In a like manner, we must pass to a working conception of God’s omnipotence. God de facto intervenes by means of his Divine power in creating the world with a set of laws, but he maintains the possibility to intervene in the course of things to modify it, through his absolute power. Reflection on the possibility of God substituting secondary causes in cognitive processes (to substitute the causality of the perceived object) leads to the idea of a deceptive God.

We find in the thirteenth century a resurgence of the problem of skepticism taken as a challenge put to our ability to gain knowledge. It is in this context (and even if Academics are not always explicitly mentioned) that the interest in the problem of our access to truth and our capacity to sufficiently justify our knowledge occurs. Schematically, we can distinguish between three types of responses to the skeptical challenge: an a posteriori response, or a weak response seeking to limit the scope of error in order to not give weight to skeptical arguments. It is a response that contextualizes knowledge. We find this notably in Thomas Aquinas and Siger of Brabant, and mostly in John Buridan. Two a priori or strong responses accept the presuppositions ofskepticism and seek to face it on its terms. It consists of one part theories of knowledge that rest on illumination (in particular, St. Bonaventure and Henry of Ghent), and another part foundationalist theories that base knowledge in a priori principles, the clearest expression of which is found in Duns Scotus. We will examine briefly the positions of St. Bonaventure, Thomas Aquinas, and John Duns Scotus.

The skeptical question appears in Bonaventure in his questions on The Knowledge of Christ q. 4, as strongly tied to the teaching of Augustine. It displays an intellectualist reading of skepticism, seemingly inherited from a misunderstood Platonism. According to the skepticism identified by Bonaventure, Divine Light is the only mean of knowledge. Bonaventure criticizes this thesis as a reduction of all knowledge to knowledge of Divine Being. It removes the distinction between worldly knowledge (knowledge of the viator) and beatific vision, between the knowledge of things in God and direct knowledge of things, between science and wisdom, and between reason and revelation. The problem with skepticism is the reduction of knowledge to the one intelligible world (knowledge of Forms). And yet, this intelligible world is inaccessible to the human mind after the fall (the Christian dimension to skepticism is explicit here). Faced with this kind of skepticism, Bonaventure defends another conception of illumination: Divine reason is the driving and regulating principle, that is, that which rules the action of human reason. There is no direct intervention as there is in the case of infused knowledge, but only God’s presence in the act of intellectual knowing. However, it is just a step from created reason from whence it gets its partial character. God is the standard of Supreme Truth that allows for all inferior truth. The consequence of this recourse to Divine rule is the stability of the object of knowledge and the infallibility of knowledge, two necessary conditions for knowledge (infallibility on the side of the subject and stability on the side of the object). Thus, the conditions for knowledge required by the skeptics (a knowledge that cannot be false and of which we know is not false) can be filled in. But, we must add a final condition for knowledge: completeness in the understanding of the object. Indeed, there are three modes of being: being in

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Spirit, worldly being, and being in the Divine Intellect. Created truth cannot grasp but the first two modes of being where truth is conditional: there is mutability of the sensible world, thus there is mutability in our thoughts of the sensible world. We must then grasp the last mode of being, which is impossible without Divine aid: the mind, not being transformed by God, has not complete, clear, and distinct knowledge. The idea of illumination is that Divine Ideas are the conditions and basis for abstraction, that is, for intellectual knowledge. There is an a priori structure to knowledge: we do not know Divine Ideas directly but they serve as standards for human knowledge. We thus find in Bonaventure a view of illumination tied to the theme of Heraclitean skepticism on the mutability of the sensible: evident knowledge supposes immutability, and this is only found in the Divine understanding. Rational thought is the highest form of knowledge that we can attain in this world, but it is a weakened form of the true intellectual knowledge that we will have in the glory of the beatific vision. We must distinguish between degrees of knowing and admit that our knowledge does not perfectly match certain criteria admitted to be necessary for knowledge such as clarity and fullness. Theories of illumination, because of the importance of the Augustinian influence, are perfect examples of the use of skepticism: they use skeptical arguments to show the necessity of a divine guarantee and the insufficiency of purely natural means of knowledge, and they refute skepticism by means of this intellectual knowledge guaranteed by God. However, we find skepticism surfacing in such a theory since the completeness of knowledge is only guaranteed in an eschatological perspective.

We can present the contextualist position (which consists in limiting the scope of the validity of skeptical arguments to limit its reach) by borrowing Thomas Aquinas’ view on the role of Adamic knowledge in the Questions on Truth, q. 18, a. 6. The question is to know if Adam, who had an ideal form of knowledge before the fall, could have erred. This thought experiment allows us to determine an exemplary situation from which we can evaluate our own knowledge. Thomas advances two arguments to show that Adam could not have been in error. First, before original sin, there could have been a defect but not a corruption. In epistemological terms, this signifies that either Adam knew truth, and he knew it completely and perfectly, or he did not know it at all. Thus, Adam could have ignored certain things (he is not omniscient) but could not err. Adam could not have incomplete knowledge since it stems from hasty assent. And yet, for Adam the assent is always proportional to the object known. Second, the intellect is created by God to be capable of truth. It can thus know the truth without error, as is attested by the indubitable knowledge of first principles. Consequently, error, the act of the intellect of confusing truth and falsity or approving an incomplete opinion, is a consequence of the fall, that is, a disorder making way for the natural order willed by God. Thus, Adam had but true, firm, and evident knowledge. Skeptical arguments allow to assure that we determine criteria of truth sufficient to elude the skeptical challenge. In the argument from dreams, Thomas replies by qualifying the weight of the objection: on the one hand, in dreams assent is not free, thus the question of error meant as epistemic responsibility does not arise. On the other hand, dreams stem from sensation, thus it is a particular case. Since Thomas does not consider that we could be dreaming permanently, the objection from dreams is not relevant; not for Adam nor for us. In return, the argument from sensible illusions poses the problem of the conditions for perception and sensory Adamic knowledge. And yet, as a good Aristotelian, Thomas reckons that all knowledge stems from experience. His answer stays no less extremely classical: there is no error at the level of proper sensibles; error is in judgment. The entire skeptical problem is thus reduced to the problem of judgment: the gap between the intellect and the sensible given. The difficulty for us, by comparison with Adam, lies thus in the mastery of sensation by the intellect and in the application of the principle of correction. As such, Adam masters his sensation perfectly thus either he recognizes a situation of appropriateness between the intellect and its object and he judges veridically, or he recognizes an absence of this appropriateness and he corrects his judgment, or if correction is impossible (as when asleep), he differs it. What the case of Adam shows us is that skepticism results from an accidental situation of separating sensation and the intellect, a separation that we can bridge by the temporary suspension of judgment and by the correction of the sensible by the intellect. Thus in a general way, even after the fall, man is created capable of truth, and in normal conditions of cognitive function we are able to judge correctly. Error is but factual, and skepticism does but emphasize that we can occasionally ignore this or that parameter in the knowing of an object. Justifying our knowledge does not then consist in excluding all possible logical objections, of rejecting a priori all sources of error, but only in delimiting the scope of what we know and what we do not know. In as much, Thomas’ answer is a posteriori and cannot, quite evidently, satisfy the skeptic.

John Duns Scotus, for his part, proposes in his Commentary on the Sentences L. I, d. 3, q. 4, a foundationalist

And rationalist response to the question of justification by explaining the role of principles while at the same time maintaining the demand of infallibility. Against the skeptical position, Scotus aims to provide three categories of infallible truths that cover the whole of the edifice of knowledge: logical truths, introspection (knowledge of one’s mental states), sensible and experimental truths. In effect, Scotus distinguishes between sensation or direct perception and experience or induction (understood as a collection of sensations). The category of logical principles, examined first, regroups at once first principles and propositions known in themselves. The infallibility of these principles is connected to their logical form: these propositions are only known by the analysis of the terms by the connection of including the predicate in the subject. The knowledge of this relation accompanies the truth of this proposition and an evident assent of the intellect. We then have here an a priori form of knowledge independent of experience. The second category of evident truths is that of sensation and experience. First, experimental knowledge (i. e., induction) rests on two parameters: the frequency of a case and the addition of a causal principle. If a repeated experience reveals constant reactions in natural agents, then we can conclude with an infallible certitude that the observed effect is proper to this agent and that it will always produce the same effect. This observational reasoning is guaranteed by a causal principle known in itself, that is, a principle which belongs to the first category, according to Scotus, and which maintains that the effect which is frequently a restrained cause is the natural effect of this cause. The principles that base experience are found in sensible knowledge in a way. We must here distinguish two situations, either the convergence of the products of different senses or a conflict. In the first case, the convergence allows to conclude with absolute and infallible certainty about perception. In effect, this convergence supplies the principle of frequency to which induction calls upon. It is, once again, the causal dimension of knowledge that enables its justification. If an object produces uniform impressions that converge on two or more senses, we can then be sure of the truth of our perceptions. Conversely, in the second case, the certainty of sensation rests on the capacity of the intellect to correct the sense. In such a situation, truth is known only through a posteriori justifications, through the help of an infallible intellectual knowledge and thanks to the convergence of several senses. Thus in the case of seeing distant things, sight may err but natural reason tells us that a distant object acts in a weakened manner. As such, once we have realized that sense cannot furnish reliable information in this context we can seek for ways to overcome this inadequacy. The third category is that of mental states: influenced by Augustine’s cogito, Scotus holds that the apprehension of our own mental states is as certain as principles in themselves. Scotus thus defends a strong response to skepticism; a response that tries hard to defend a model of knowledge where truth, evidence, and infallibility are necessary conditions for knowledge. To do so, he employs a foundationalist and rationalist conception of knowledge: first principles of knowledge, the most evident principles, are a priori principles known by the intellect outside of all sensation. And these principles are the ultimate basis of knowledge, which permit the infallible justification of sensible truths. Therefore, we have of the movement of foundation of knowledge on intellectual principles: sensible truths are based on the principle of causality that justifies the cognitive value of sensation. The same causal principle, along with the principle of uniformity of nature, warrants induction. Thus, all reliability of experience comes from first principles, known a priori only through the analysis of terms.

Next to these attempts to refute skepticism we find a group of philosophers defending a fallibilist conception of knowledge, such that the majority of our knowledge is never absolutely evident and always susceptible to be otherwise. While most of these philosophers are active in the fourteenth century, the most important and the only to explicitly call himself a skeptic (academicus), is a philosopher from the twelfth century, John of Salisbury. This philosopher insists on the cognitive fallibility of Man; a weakness that renders difficult his access to truth: Man must be satisfied with mostly having likely knowledge, and his probabilistic truths conflict such that, Man, incapable of overcoming this is reduced to uncertainty and hesitancy (Metalogicon, IV, 40). John of Salisbury’s theory of knowledge allows putting this moderate conception of skepticism into place. This seems to be a fallback to a kind of fallibilism and a probabilism tied to the imperfection of our cognitive apparatus. Proposing a phenomenology of knowledge in several places, Salisbury emphasizes how the process, by which we gain knowledge passing through sensation, imagination, and memory (faculties of the synthesis of sensation) and then, by the prudence of reason and an intellectual judgment, runs the risk of incompleteness and error at each step. In describing the progressive elaboration of our concepts, stemming from sensation up to reason, he stresses hard that, fundamentally, all knowledge is approximate knowledge. The work of analysis and synthesis run at each level by different faculties, works to define precisely the object of knowledge by situating it by its differences and similarities, in relation to what is

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Already known. What interests John of Salisbury are the steps of this approximation and the degrees of justification wherein our knowledge claims to be. A distinction is imposed between judgment (sententia) and opinion. Judgment, which is the object of prudence, creates a strong confidence that practically excludes error and allows a reliable approximation of truth, meanwhile opinion is an unjustified belief (Metalogicon, II, 5). John of Salisbury thus distinguishes between degrees of justification that determine an assent more or less firm depending on the reliability we can claim to. The importance accorded to the probable is justified both by the reality and the limits of our faculties. As such, to judge veridically with absolute certainty supposes on our part a capacity to judge which events are necessary. But specifically, such complete apprehension of the laws of nature is impossible for us and reserved to God alone: it is too difficult from our point of view to distinguish that which occurs often from that which occurs always (Metalogicon, II, 13). It is thus a recourse to a theme from Christian skepticism (only God knows truly what is true) which justifies the recourse to the probable in the study of nature, as far as possible, where thought about the contingent is permitted. From here, we are driven to a philosophical skepticism: the difficulty to perceive truth inclines us to follow the Academics. We must renounce certitude and necessity in the field of natural philosophy since all that is corporeal and mutable, is contingent and free of necessity, and we must admit that demonstration is not possible but in the domain of mathematics.

See also:  > Augustine > Bonaventure > Certainty

>  Divine Power > Epistemology > Henry of Ghent

>  Induction > John Buridan > John Duns Scotus

>  John of Salisbury > Knowledge > Nicholas of Autrecourt > Nicholas Oresme > Peter Auriol > Robert Holcot > Sense Perception, Theories of > Siger of Brabant

>  Thomas Aquinas > William Crathorn > William of Ockham