John Locke: The “Jocose Problem” and the Theoretical Foundation of Toleration

The Molyneux Problem (II.9.8)

In the first edition of the Essay (1690), Locke noted that human perception, even regarding everyday experiences, is more complicated than it seems: “the ideas we receive by sensation are often in grown people altered by the judgment, without our taking notice of it” (2.9.8). It is easy to underestimate the extent to which ordinary perceptions of the world are shaped by our judgments. As Locke indicates by the following example, these mental interventions in perception occur at fundamental levels:

If we look at a globe of a uniform color at a distance, for example, the appearance of the body of the figure is a plane (or flat) circle. We can imagine an image of plane circle and a globe of the same color near each other and the shape and extension of each are identical: a plane circle. The similarity between figures can be missed, however, because the slight differences between the two make it appear that one is only a colored plane circle and the other a sphere or globe. In this case, the right-hand figure has two small white circles in the upper hemisphere and a darkening color gradient in the lower hemisphere. These slight variations imitate the appearance of a three-dimensional globe on a flat surface that appears convex due to the reflections of light.

Contrary to initial ‘perception,’ however, any reader can simply touch both figures on this page (or computer screen) and confirm they are merely flat circles. It is human judgment that posits the existence of a sphere. The tendency to ‘automatically’ miss the similarity in the figures is because we have “been accustomed to perceive what kind of appearance convex bodies are wont to make in us, what alterations are made in the reflections of light by the difference of the sensible figures of bodies” (2.9.8). They are both plane figures, albeit “variously colored,” but “habitual custom” makes us prone to the imperceptible act of supposing an extended convex figure where one does not exist. ¹⁴ The perception of the reflections of light caused by convex shapes is an experience that takes place countless times in daily life. It has been experienced so many times that the chain of thoughts which prompt us to judge convexity is hidden in normal circumstances (II.9.9–10). Locke illustrates the issue by imagining a painter who is so adept at his craft that viewers are fooled into judging the presence of an extended sphere (II.9.8 ln. 25-33). An artist’s ability to induce this faulty judgment depends the habitual human tendency to identify figure by the reflections and patterns of light. Even if the painter’s deception is only temporary, for Locke it illustrates that even our ‘perceptions’ of simple objects in the external world, are sometimes derived from judgments rather than sensations of material bodies. ¹⁵ This tendency to mistake our judgment as an accurate perception at this fundamental level points to even greater potential errors in more complex and potentially controversial ideas.

After corresponding with William Molyneux about possible improvements to the Essay, Locke decided to expand II.9.8 to include a jocose problem suggested by this “ingenious and studious promoter of real knowledge” and “my friend”:

“Suppose a Man born blind, and now adult, and taught by his touch to distinguish between a Cube, and a Sphere of the same metal, and nighly of the same bigness, so as to tell, when he felt one and t’other, which is the Cube, which the Sphere. Suppose then the Cube and Sphere placed on a Table, and the Blind Man to be made to see. Quære, Whether by his sight, before he touch’d them, he could now distinguish, and tell, which is the Globe, which the Cube.” (II.9.8.1–7)

Both Molyneux and Locke were certain the answer was no. Even if a blind man could “unerringly name” a globe and a sphere by touch, he would be incapable “at first” of naming them by sight if he gained his vision. ¹⁶ As illustrated in Locke’s original example (above) the ability to recognize the two solid figures by sight alone depends upon making judgments about appearances through the reflection of light. A totally blind individual, according to Locke, can have no comprehension of reflections because “light” itself is completely unknown to them (II.8.17, II.9.9, III.4.10, III.4.13). This is also true for the ability of the blind to comprehend colors which Locke uses as a primary example of the demonstrable limits of human understanding (I.4.19, II.1.6, II.2.2, II.3.1, II.4.5–6, II.9.8, II.10.5, II.21.73, II.22.11, III.4.12–13, III.6.9, III.9.5, IV.3.23, IV.18.3). ¹⁷ The same is also true of “sounds” for those who are deaf (II.2.2, II.4.5, III.9.5). As in the case of Molyneux’s cube and sphere, a deaf person who is unerringly able to distinguish between a “trumpet” and, for example, a tuba by sight and touch would be unable to identify either by suddenly being able to hear them from another room (II.4.5, III.4.11). Locke is unequivocal: anyone who has never experienced the simplest of perceptions, like smelling a lily or tasting a pineapple, has no means by which to understand them (II.1.6, II.2.2, III.6.9). Whether caused by sense deprivation, or lack of experience, human understanding is constitutionally limited: “the simple Ideas we receive from Sensation and Reflection, are the Boundaries of our Thoughts; beyond which, the Mind, whatever efforts it would make, is not able to advance one jot” (II.23.29). In these cases at least, the argument of the Essay establishes strict bounds of human understanding.

In order to understand Locke (and Molyneux), the importance of this precise limitation cannot be overestimated. The comprehensive “Doctrine of Ideas” delineated in the Essay as a whole is confounding at times, but the special status of “simple ideas” (e.g., light, motion, white, and red) is beyond question. ¹⁸ All ideas and knowledge, even the most complex and lofty, are composed of them (II.1.24–5, II.2.2, II.7.10, II.12.1–2, II.12.8, II.13.1, II.22.9, IV.6.1). Any notion “whatsoever” is a simple idea, or a complex composition of “simple ideas” that must be explained by being resolved back into them (I.1.8 with e.g., II.13.27, II.15.9, II.28.14, II.29.12, III.4.12). ¹⁹ Simple ideas are the “proper Standard” by which all other ideas should be judged (III.9.13). By definition, they are the foundation stones of all possible human knowledge. They are “the Foundation, and sole Matter of all our Notions, and Knowledge” (IV.18.3 with II.2.2). Any conceivable idea that cannot be explained in terms of simple ideas is a mere “name” or “indeterminate idea,” and therefore Rubbish. ²⁰ Further, Locke’s only self-proclaimed contribution or discovery in the history of philosophy is his discovery that “simple ideas” are so fundamental they have no definition (III.4.4–14 with e.g., II.13.15). No combination of words can convey the meaning of, for example, light, motion, or any single color, sound, taste, or odor to someone who has not experienced them. Simple ideas have the advantage of being the most clear and distinct ideas human beings can possess (e.g., II.32.9). Children can even understand them before they can vocalize names for them (e.g., hunger, sweet, and hot!). ²¹ Both their clarity and their imperviousness to words (definitions) are illustrated in a humorous anecdote:

A studious blind Man, who had mightily beat his Head about visible Objects, and made use of the explication of his Books and Friends, to understand those names of Light and Colours, which often came in his way; bragg’d one day, That he now understood what Scarlet signified. Upon which his Friend demanding, what Scarlet was? the blind Man answered, It was like the Sound of a Trumpet. Just such an Understanding of the name of any other simple Idea will he have, who hopes to get it only from a Definition, or other Words made use of to explain it. ²²

The reason for Locke’s decision to add the Molyneux Problem in the second edition of the Essay becomes clear by considering another element of it that has not received due attention. ²³ Rather than being an additional and unnecessary repetition of the demonstrable limits of individuals confined to sensations of four senses, it is a criticism of all human beings who claim, consciously or not, to understand ideas beyond their ability to perceive them. The impetus of Molyneux’s query was his effort to test “Diverse and Ingenious” readers of Locke’s Essay in order to determine if they understood the Englishman’s “Book and Notions.” Hardly any of them were able “at first dash” to give the correct answer. ²⁴ Locke inserts Molyneux’s Problem, for the same reason: “This I have set down, and leave with my reader, as an occasion for him to consider, how much he may be holding to experience, improvement, and acquired notions, where he thinks, he has not the least use of, or help from them” (II.9.8). ²⁵ Upon review of the plethora of examples involving blindness, it is clear Locke’s use of them from the beginning is as a stand-in for the issues surrounding human perception tout court: “And had Mankind been made with but four Senses, the Qualities then, which are the Object of the Fifth Sense, had been as far from our Notice, Imagination, and Conception, as now any belonging to a Sixth, Seventh, or Eighth Sense” (II.2.3, with IV.3.22–3, IV.18.3). When men claim to “proceed beyond these simple Ideas, we have from Sensation and Reflection,” there is nothing but “Blindness and Ignorance” and this includes the idea of “God himself” (II.23.32).

In order to see this last point more succinctly, it is helpful to examine the likely source of Molyneux’s Problem in the thought of Thomas Hobbes. In 1641, a set of sixteen objections made by Hobbes against Descartes were published along with Descartes’ replies as an appendix to the Meditations on First Philosophy. The exchange is complex, but the heart of the dispute centers on two connected issues of 1) the status or definition of Idea and 2) Hobbes self-purported demonstration that Descartes’s entire discourse “falls to the ground” and his idea of God is “exploded.” ²⁶ Hobbes’ main tack is his dogged refusal to admit that there is a meaningful definition of “idea” that is not derived from a “corporeal body.” He snubs Descartes’ admittedly loose use of words like Soul, Chimera, Angels, God, Eternal, Infinite, Omniscient etc. ²⁷ According to Hobbes, “There is a great Difference between Imagination (that is) having an Idea of a Thing, and the Conception of the Mind (that is) a Concluding from Reasoning that a thing Is or Exists” (Obj. IV). There is a difference between ideas perceived “in outward Objects” and “Names and Appellations” made of words joined in artificial “Copulation or Concatenation” (Obj. IV). Do such names signify anything? ²⁸ For example, men “Impose the Name of Angel,” but is it like a “Flame” or “a Pretty Little boy with Wings”? Fire and boys are ideas of “sensible Things,” but the use of these sensible things to describe beings beyond human understanding exposes the inscrutable character of Angels. Whatever an Angel is alleged to be, it can be neither a fire nor a boy. The settled belief in the name “Angel” requires men to posit a definition compounded of aspects of sensible objects and, for Hobbes, this necessity of defining invisible bodies by corporeal bodies inadvertently proves we only know corporeal bodies. ²⁹ In the same way, men may venerate the Name of God, but there is no discernable idea of God, in a way Hobbes will allow. All human beings are “like one born blind, who being brought to the Fire, and perceiving himself to be Warmed, knows there is something by which he is warmed and Hearing it called Fire, he Concludes that Fire Exists, but yet knows not of what shape or Colour the Fire is, neither has any Image or Idea thereof in his Mind.” Even though a partial or imperfect idea of a fire can be obtained through the heat, sound, [and smell], other crucial qualities like light, color, and its flicker-y motion would be wholly unknown. For Hobbes, this partial knowledge is useless; or no idea at all. ³⁰

The blind individuals in the examples put forward by Hobbes, Locke, and Molyneux are all in the same predicament. A proposer gives them a “name” (fire, scarlet, cube and sphere) along with a description, but this is not sufficient to accurately convey an understanding of the idea. According to Locke, this unreflective use of “names” imparts “secret” references that create “most of all disorders [in] Men’s Thoughts and Discourses” (II.29.12, III.9.14, III.10.15, III.10.18–19). Because names are habitually used, their precise meaning – the idea(s) they represent – are blurred. Two disputants, for example, could be using the same name for different ideas, or the same idea mistakenly ranked under two different names (III.9.6, III.9.13, III.10.20, IV.3.19: compare II.28.16–19). We could imagine two blind men in a pitched argument over whether or not the color of fire is red inclining to orange, or simply scarlet. For Locke, however, the power of common names to mask our ignorance of the ideas they represent applies to all men who knowingly or unknowing employ indeterminate ideas. He uses the metaphor of a Chiliaëdron to illustrate the point. It is a 1000 sided regular polygon. Very exact calculations are possible for both its interior and exterior angles. But grasping these peripheral characteristics cannot constitute a determinate idea. In fact, it is humanly impossible to visibly distinguish a Chiliaëdron from a 999-sided polygon. We have “no precise Idea of its Figure,” yet are “very apt to impose ourselves, and wrangle with others” because our knowledge of “part of the Idea” of the “Name” leads to assumptions about more obscure aspects of a Chiliaëdron (II.29.13–4). ³¹ The stakes regarding a precise understanding of a polygon are likely harmless, but the names of other imprecise ideas are not. Children become acquainted from a very early age with the names of “Honor, Faith, Grace, Religion, Church” and eventually settle, or more likely “swallow” a definition however confused or idiosyncratic. “And so all the contests that follow … are only about the meaning of a Sound. And hence we see, that in the interpretation of Laws, whether Divine or Humane, there is no end” (III.9.9 with III.9.6). Just as we saw in II.9.8, very few men take the time to distinguish between notions that have been understood by experience, improvement, or mere testimony. In a real sense, it is arguments over the definitions of names like justice and gratitude (III.5.12), murder and sacrilege (III.9.7), glory and gratitude (III.9.8), modesty and frugality (III.9.18) that lead to the greatest societal conflict.³² These indeterminate ideas become “in grown people altered by the judgment, without … taking notice of it,” the flash points of controversy in matters of life and death. As the Essay proceeds, the political consequences of the earlier epistemological arguments become more pronounced.

We can conclude this section by noting Locke’s invitation for readers to imagine an encounter with alien beings from some distant planet (II.2.3, IV.3.23–27, IV.16.12, IV.18.3). These aliens may have more than five senses, or possess powers of, for example, sight and hearing that are more acute than our own. In addition, they might have experiences of physical phenomena that do not exist on earth, or the ability to understand aspects of our world which are imperceptible and hence invisible to us. Locke does not rule out these possibilities, and indeed encourages readers to ponder alien existence as likely given the vastness of the universe. With regard to their extraterrestrial knowledge, however, he is quite certain. Human beings would be completely incapable of understanding any of it unless experienced, or communicated by the use of the “simple ideas” we already possess. Access to new ideas, Locke contends, is ultimately limited to experience and this means a condition of “incurable ignorance” (IV.3.25). ³³ Just as those with only four senses are incapable of understanding ideas perceived through a fifth, all human beings are precluded from ideas derived through a sixth, seventh, or eighth sense. We could not deny the accuracy of the new alien reports of yet unimagined phenomena, but any meaningful understanding of their new news is impossible. Further, even if aliens were able to “imprint” the ideas available to a sixth sense directly into the mind of a human being, this individual would be incapable of expressing their newfound understanding to others (IV.18.3). The strict boundary of all human understanding is limited by our access to the foundation stones of “simple ideas.” Locke is so certain of this limitation; he contends that even “the immediate hand of GOD” or any conceivable “Revelation” can only be successfully communicated to us through the simple ideas we already possess or can experience ourselves (IV.18.3).

Conclusion

After the second edition of the Essay (1694) was published, the addition of the “Molyneux Problem” attracted attention. Locke’s own fame was rising, and both those who admired and criticized the Essay were curious about substantial changes and what they might disclose about Locke’s philosophy. One surviving example of these private discussions is a letter between two Irish clergymen, Edward Synge and Dr. Francis Quayle, given to Molyneux in confidence. Molyneux forwarded it to Locke, claiming that it would be easy to “discover by what false steps this Gentleman is lead into his error.” ³⁴ The letter is striking because Synge attempts to explain why a formerly blind man would be able to differentiate between a cube and a sphere, but he uses a vocabulary derived from the Essay. Synge’s letter reveals that he was a serious reader of Locke’s, even though he concludes that the blind man would have little trouble differentiating between the cube and sphere after gaining his sight. Simply stated, “A man born blind may have a true (though perhaps not a perfect) Idea of a globe and of a Cube and of some difference which is between them.” The first sight of the images of the two objects would immediately appear different: one of them alike “on all sides” [the sphere] and the other “not alike in all parts of its Superficies” (De Beer 1979b, 495). If, as I have suggested, the Molyneux Problem was added as a kind of test for readers of the Essay, Synge’s response indicates his failure to think through the consequences of Locke’s argument leading up to II.9.8. A partial—“not a perfect”—understanding of an idea is useless at best, and possibly dangerous. This difference of opinion over a “Jocose Problem” might seem frivolous at first glance, but Locke’s harsh reaction to Synge’s position indicates the seriousness of its inclusion in the Essay and its political importance:

“how hard it is, for even ingenious men to free themselves from the anticipations of sense. The first step toward knowledge is to have clear and distinct ideas; which I have just reason every day more and more, to think few men ever have, or think themselves to want; which is one great cause of that infinite jargon and nonsense which so pesters the world.” ³⁵

This concern for the demonstrable effects of “jargon and nonsense” is a constant drumbeat in the Essay (e.g., II.1.19, II.13.18, III.9.21, III.10.15, IV.3.22, IV.16.4). It is the underlying cause of the endless debates among philosophers and theologians, but it is also the root of political “Disputes” and “Mistakes in the world.” Without firm boundaries between what can be known versus merely posited, there will be no end to vain disputes in “Matters of Religion” (IV.18.1). The Essay is the most philosophically abstract of Locke’s published writings, but the intention of providing an intellectual foundation for religious toleration and peaceful political life is also present (e.g., II.1.19, III.9.21, IV.3.22, IV.16.4). ³⁶ When this aspect of the Essay is recognized, it becomes an almost purposeful invitation to compare it to the more widely read and more politically effective Letter Concerning Toleration.

A great deal of the rhetorical power and success of the Letter is its humane call for peace, liberty, charity, commerce, personal safety and comfort. In turn, these practical considerations are strengthened by Locke’s claims that personal belief cannot be coerced by force, that the express and positive commands in holy scripture are minimal and uncontroversial, and that it is impossible for human beings to judge between “the great variety of ways men follow.” ³⁷ This appeal to “terrestrial enjoyments” combined with Locke’s outline of his theological and philosophic positions explain the Letter’s influence. Toleration is not only politically beneficial, but it emerges as the central duty and the chief characteristic of true religious believers. Confidence in Locke’s claims is further adduced by his use of very sharp distinctions that seemingly alleviate all grounds of civic and religious controversy. For example, the Letter continually contrasts “The Business of True Religion” and “the Business of Civil Government” (Locke 1983, 23, 26, 31, 39, 53). These precise separations are not exactly clear in all circumstances, but the argument of the Letter depends on them. He repeatedly refers to obvious differences between ecclesiastical and civil matters, private and public, inward belief and outward behavior, persuasion and force, speculative and practical thinking, and even to the difference between frivolous and Substantial/Fundamental religious beliefs. Unless we “distinguish exactly” the “just bounds” of our concernments there will be no end to civil controversy. It is the “confounding” or “intermeddling” of different types of “businesses” in our thinking that leads to political violence (Locke 1983, 26 with, 48, 55, 56). There is a striking exception to this confident procedure, however, when Locke points to the unique status of “Moral Actions.” Unlike other issues discussed in the Letter, moral actions contain a mixture of speculative and practical considerations. This poses “a great danger” to society because moral actions fall within “the Jurisdiction both of the outward and inward court” (Locke 1983, 46–47, 49–51). But if moral reasoning and action is a legitimate concern of both civil and ecclesiastical authorities, the entire procedure of the Letter becomes questionable. Locke’s admission regarding the ambiguity in the “bounds” of moral reasoning serves as a reminder that there are deeper considerations the Letter depends upon, but does not provide. Its practical purpose limits its scope. ³⁸

The most focused arguments for toleration in the more philosophical Essay (IV.16-18), begin in a more modest and forthright tone. Rather than confident reliance on the precise “Business of True Religion,” Locke highlights the political difficulty (or impossibility?) of dissuading others of their deeply held views (IV.16.3–4). Even those in a possession of arguments formed by “no Other Guide but Reason” cannot expect to gain the immediate assent of others. A diversity of “Opinions” is “unavoidable” and “we cannot reasonably expect” to change the “Sentiments” of gainsayers. This is especially true of those whose opinions were “received from God Himself, or from Men sent by Him.” ³⁹ In these circumstances, the only conceivable hope for “Peace, and the common Offices of Humanity, and Friendship” is to refrain from “magisterial,” “insolent and imperious” expectations of immediately changing the minds of others (IV.16.4). This is the same conclusion as the Letter—every individual is orthodox to himself ⁴⁰ —but the emphasis here is on the impossibility of communicating precise distinctions between matters of faith and matters of reason. This echoes the Letter’s deepest contention about the certain impossibility of man’s ability to understand “the way” of God, but there the basis or proof of his contention was not provided.

The Essay’s unexpected departure from the Letter is striking. Locke admits in IV.16.3 that there are a small group of men who “have fairly and truly examined, and thereby got past doubt in all the Doctrines they profess, and govern themselves by.” Men “who have examined to the bottom all their own Tenets” may not “immediately” assent to arguments containing “no other Guide but Reason,” but eventual agreement that is “past doubt” is possible. ⁴¹ Unfortunately, such knowledge is politically irrelevant. The number of individuals who examine before they assent (or disagree) are so few, their “juster pretense” to guide others can never be politically effective. Despite this admitted irrelevance, the Essay does include an attempt to demonstrate the possibility of “clear and determined specific Ideas” that would be necessary in order to end “vain disputes” that cause “great Disorders …Disputes, and … Mistakes in the World” arising from “Matters of Religion” (IV.18.1–2). Indeed, unlike the Letter, Locke not only asserts, but claims to demonstrate the precise “Boundaries between Faith and Reason.” It is the same demonstration that began in earnest in the early pages of Book II of the Essay to which the Molyneux Problem was added, but now the theological consequences of his earlier epistemological position become explicit. If, as he maintains, all possible human knowledge is ultimately derived from our senses and reflections concerning “simple ideas” (II.2.7–8), our reason is fundamentally bounded by recourse to them. Simple ideas are the “sole Matter of all of our Notions, and Knowledge,” and any other source of knowledge is impossible. Locke is well aware that direct communication with god, traditional revelation, scripture, and miracles (either reported or witnessed) are purported to be additional sources of knowledge, but our access to them is limited to what we are already capable of knowing without them. Human beings are irremediably occluded from “whatever [other] Things” are reported from these other sources as “the Idea of any color” to a blind person. Locke is so certain of his position, he claims the “new Ideas” reported by the Apostle Paul cannot be understood beyond “Things, as Eye hath not seen, nor Ear heard, nor hath it entered the Heart of Man to conceive” (IV.18.3–4 with IV.19.12). ⁴²

It is important to pause and recognize that Locke’s strict limitations in the Essay regarding the difference between Faith and Reason do not depend upon a predetermined or assumed impossibility of these other sources of knowledge. Just as in the case of aliens from “Jupiter or Saturn” or angels, there is no need to deny their existence or the possibility they possess undiscovered knowledge of the universe (IV.3.23–27). The central issue is the human ability to understand them. God could directly communicate with human beings, but these divine communications would necessarily be composed of simple ideas already known through experience. The possibility of higher beings “imprinting” new ideas in the mind, or human discoveries through a “sixth sense” need not be denied. According to Locke, however, these new ideas are incapable of being communicated to anyone else who has not experienced them. This predicament is identical to a blind man who can unerringly distinguish between a globe and a cube by touch. One is a spherical thing, the other is not, but the ability to see them from any distance depends on prior experience of light and its reflection. Neither the most acute sense of tactility nor the most accurate definitions make either “light” or “reflection” comprehensible. As Locke would suggest, God, in his infinite wisdom, only provided mankind with five senses and all of us are confined to utter darkness concerning speculations beyond them. ⁴³

Philosophic interest in the “Molyneux Problem” peaked during the 18^th Century, when its connection to political and religious questions had more immediate gravity and interest. Molyneux’s jocose problem is a “brain-teaser,” but it highlights Locke’s central concern to illustrate the extremely narrow basis of human knowledge. His effort to delineate the limits of human understanding reveals that our ignorance is “infinitely larger than our knowledge” (IV.3.22). This has the intended effect of reducing the uncritical acceptance of authoritative appeals to immaterial spirits or even God (e.g., IV.3.27). But the Essay goes even further. Locke’s insistence on the precise criteria of “determinate ideas” and their ultimate connection (cohesion) to simple ideas is so rigid that it becomes unclear whether human knowledge is even possible (IV.3.6, IV.3.12–14). If this were the final teaching of the Essay, whatever political advantages gained from reducing the claims of religious authorities would be negated by the inability to make any decision that deserves the name reasonable. It is for this reason that Locke famously turns to the importance of “Probability” as the most frequent guide to action (IV.14-16). Both individually and politically, decisions must often be made without adequate knowledge (IV.14.3, IV.15.2, IV.161-2). This turn to probability appears to be a hedge, or even contradiction of his preceding epistemological argument, but it is consistent with the Essay’s overall teaching on tolerance. ⁴⁴ By demonstrating our reliance on probability of judgment, the basis for zealotry (religious or secular) and intolerance of a “diversity of Opinions” is radically diminished (IV.16.4, IV.3.22).

For Locke and Molyneux, however, the precise “Boundaries between Faith and Reason” (IV.18.1) was a matter of certainty. Even the human tendency to mistake individual “judgment” for perception of the external world can be overcome (II.9.8). ⁴⁵ Human knowledge is fundamentally limited to the senses and to the reflections that cohere to them. As we have seen though, the political utility of this theoretical foundation is questionable. Locke is forthright in his admission that the majority of mankind lack “the leisure, patience, or means” necessary to arrive at “certain and demonstrative Knowledge” (IV.16.3–4). If Locke’s deepest theoretical foundation for tolerance is politically irrelevant, is it also useless? What is the practical difference, for example, between the “defeatism” by which Habermas characterizes 21^st Century intellectuals (Habermas 2010) and Locke’s own efforts? Neither, ultimately, seems able “to maintain Peace, and the common Offices of Humanity, and Friendship, in the diversity of Opinions” (IV.16.4). Perhaps Locke had only humble ambitions for the argument of the Essay—to reach those few readers with the leisure and capacities to recognize the radical limits of human knowledge as the beginning point of their own private studies. ⁴⁶ On the other hand, the early success of the Essay also points to the possibility that this humble starting point was understood as a necessary first step toward influencing a much wider audience. It was the realization that Locke’s literary efforts seemed to be gaining practical influence that prompted Molyneux to pronounce:

tis a Good sign, and shews the World not so averse to truth, when fairly laid open. To have Truth Prevail the only way is calmly and meekly to publish it, and let it shift for it self; Magna res est Veritas et Prævalebit [Great is truth and shall prevail]: ‘ twil make its own Party Good without Fire and Fagot. ⁴⁷

Locke shared in this hopefulness as he prepared the fourth edition of the Essay and other writings: “what good we can do for those whom we wish well. Great things have sometimes been brought about from small beginnings well laid together.” ⁴⁸ Only 6 years after the first edition of the Essay, it was so popular in Oxford and Cambridge that Locke’s “Doctrine” was being publicly discussed and debated in sermons in the most prestigious religious pulpits in England. ⁴⁹ Locke’s Letter Concerning Toleration has had an undeniable influence in western political thought, but its practical success was also due to the Essay’s victory among intellectuals regarding the theoretical issues at the root of the Letter’s arguments.