Code: TP-7


Peirce’s Scientific Spirit and the Highest Maxim of Logic: On the Incompatibility between Philosophy and Christianity


Traditional Paper


Paper Word Count: 3397

Abstract Word Count: 149






Can a Christian be a scientist or a philosopher?  According to Charles S. Peirce’s scientific method, some common versions of Christian religiosity are incompatible with the methodology of science and philosophy. In my estimation, Peirce’s view constitutes one of the strongest challenges ever presented to contemporary Christian scholars and professionals.  Peirce’s challenge does not stem from an anti-religious sentiment or from a biased secular view; instead, it is grounded in his understanding of the logic of science or what he refers to as the highest maxim of logic: to want to learn the truth. First, I will explain Peirce’s notion of the scientific method and argue that its foundation is his highest maxim of logic. Second, I will explain how theoretical and practical reasoning are connected to the scientific method, according to Peirce. Finally, I will explain why the scientific method and some versions of Christian religiosity are incompatible.  


Can a Christian be a scientist or a philosopher?  According to Charles S. Peirce’s scientific method, some forms of religiosity clash with the methodology of science and philosophy. If this thesis is correct, then the Christian who practices this form of religiosity cannot be considered a true scientist or philosopher when he or she is engaged in research that may come into conflict with his or her religious beliefs. This thesis presents a difficult challenge for the Christian community, since its truth implies that Christians ought not to partake in scientific or metaphysical research that may involve questions related to Christian belief. In my estimation, Peirce’s view constitutes one of the strongest challenges ever presented to contemporary Christian scholars and professionals.  Peirce’s challenge does not stem from an anti-religious sentiment or from a biased secular view; instead, it is grounded in his understanding of the logic of science or what he refers to as "the highest maxim of logic".  The paper is divided into three parts. First, I will explain Peirce’s notion of the scientific method and argue that the foundation of the scientific method is Peirce’s highest maxim of logic. Second, I will explain how theoretical and practical reasoning are connected to the scientific method, according to Peirce. Third, I will argue that as a consequence of Peirce’s conception of scientific method and its exclusivity to theoretical reasoning, the Christian person is precluded from partaking in true scientific investigations that involve Christian belief and thus is excluded from the respective true scientific community of inquirers.

1.  The Scientific Spirit and The Highest Maxim of Logic

Peirce believed there was an intricate relationship between science and logic. He says, "In the same way, every work of science great enough to be well remembered for a few generations affords some exemplification of the defective state of the art of reasoning of the time when it was written; and each chief step in science has been a lesson in logic."[1] While Peirce spent most of his career working as a scientist for the United States Coast Survey, he considered himself a logician. His early writings were on the "Illustrations of the Logic of Science". The demarcation between the disciplines of logic and science was not as defined as it is today. As a result, we must understand Peirce’s conception of logic as much broader than our contemporary understanding of it. Having said this, it should not be surprising that what Peirce considered the foundation of the scientific method is his highest maxim of logic.    

1.1 The Scientific Spirit

A definitive way of grasping Peirce’s understanding of the scientific method is by considering his conception of science. Peirce believed that science requires neither truth nor method per se, but only an attitude or "spirit." Science is the spirit that tirelessly seeks truth and is relentless in that search. Peirce describes what science is as follows:

That which constitutes science, then, is not so much correct conclusions, as it is a correct method. But the method of science is itself a scientific result. It did not spring out of the brain of a beginner: it was a historic attainment and a scientific achievement. So that not even this method ought to be regarded as essential to the beginning of science. That which is essential, however, is the scientific spirit, which is determined not to rest satisfied with existing opinions, but to press on to the real truth of nature. [2] 


Peirce’s understanding of the scientific spirit is not equivalent to our understanding of the scientific method, that is, the steps science uses to carry out an inquiry. The latter is itself a result of scientific inquiry, a result of the search for truth. The only thing essential to science, therefore, is the scientific spirit:  the determination "not to rest satisfied with existing opinions, but to press on to the real truth of nature".

1.2 The Scientific Spirit is the Highest Maxim of Logic


As Peirce prepared his 1898 Cambridge Lectures, he wrote to James describing the content of each of the seven lectures. In his description of the third lecture, which eventually was delivered as the fourth, he says: "My third lecture is to be upon the highest maxim of logic, which is that the only strictly indispensable requisite is that the inquirer shall want to learn the truth." [3] The claim that "to want to learn the truth" is a maxim of logic, let alone the highest, may sound strange to contemporary philosophers, especially logicians. Nevertheless, Peirce’s conception of logic is broad compared to the more narrow understanding of logic today; it is interrelated and inseparable from his theory of semiotics [4] and the categories[5] as well as his theory of pragmatism, which he refers to as "a mere maxim of logic"[6]. We should not lose sight of this in the discussion that follows.    

What does this highest maxim of logic mean? What does it mean to want to learn the truth?  It refers to an attitude on the part of an inquirer. It is a property that characterizes the predisposition that an inquirer should have in his or her search for truth. Peirce reduces the meaning of this maxim to: Do not block the way of inquiry. Peirce explains, 

Upon this first, and in one sense this sole, rule of reason, that in order to learn you must desire to learn and in so desiring not be satisfied with what you already incline to think, there follows one corollary which itself deserves to be inscribed upon every wall of the city of philosophy.


Do not block the way of inquiry[7]



Peirce believes that to block the way of inquiry is inconsistent with wanting to learn the truth. Peirce identifies and discusses four ways in which the path of inquiry may be blocked: the first is by "absolute assertions," which are submitted as self-evident truths; the second is by claiming that something transcends human knowledge and thus cannot be known; the third is by claiming that some proposition is basic or inexplicable; and the fourth is to hold that some law or truth has found its last and perfect formulation.  Peirce does not accept any of the above as a sufficient reason to terminate inquiry, because he envisions these as temporary situations and not as having the final say on the matter. These obstacles to the path of inquiry are not specifically related to religious belief and they cannot be attributed solely to Christians.   Indeed, many forms of scientism, skepticism, and rationalism are avid proponents of the aforementioned roadblocks to the path of inquiry. For the purposes of this paper, however, my interest lies with Christianity and whether there is something inherent in its nature that blocks the path of inquiry. In this paper, I will argue that there is a fifth obstacle to the path of inquiry that is inseparable from Christianity (at least in a majority of forms of religiosity), namely, the mingling of practical reasoning with theoretical reasoning. 

2. To Want to Learn the Truth: The distinction between practical and theoretical reason.

        Peirce emphasized the importance of method and how each discipline required a distinct method. He was aware of the Aristotelian distinction between theoretical knowledge and practical knowledge and the different methods of reasoning that accompanied each. Peirce began his 1898 Cambridge lectures by drawing on this distinction:

This theoretical science was for him [Aristotle] one thing, animated by one spirit and having knowledge of theory as its ultimate end and aim. Aesthetic studies were of a radically different kind; while Morals, and intellectual activity, radically foreign in its nature and idea, from both the other two. Now Gentlemen, it behooves me, at the outset of this course, to confess to you that in this respect I stand before you an Aristotelian and a scientific man, condemning with the whole strength of conviction  [my emphasis] the Hellenic tendency to mingle Philosophy and Practice. 


Not only did Peirce believe it vital to draw the distinction between theory and practice but also he thought it was just as important to maintain it in a conscious and reflective manner, for he realized that there is a strong human tendency to conflate practical affairs with scientific issues. Peirce claims that concerning matters of "Vital Importance" or practical matters, whether of everyday business or great crisis, theoretical reasoning is of very little use. These matters are better handled by human sentiment and instinct than by reason.  He says,  "A Logica Utens, like the analytical mechanics resident in the billiard player’s [instinctual] nerves, best fulfils familiar uses."[8] A great billiard player does not understand the theoretical explanations behind his great shots at the pool table. Moreover, his having this theoretical knowledge would probably benefit the pool player’s game very little. It should be clarified that ratiocination may be embedded in human sentiment and instinct but these natural cognitive acts are not the same as theoretical reasoning. For instance, a person may employ many logical deductive theorems in conducting business throughout the day, such as disjunctive syllogisms, without recognizing that he or she is doing so, and thus without theorizing.

       On the other hand, Peirce believed that just as theoretical reasoning is not and should not be involved in practical matters, sentiment should not be involved in the resolution of theoretical and scientific affairs. Peirce says: "I would not allow to sentiment or instinct any weight whatsoever in theoretical matters, not the slightest.  Right sentiment does not demand any such weight: and right reason would emphatically repudiate the claim if it were made."[9] The only exception to this would be the role of instincts in offering hypotheses.  Peirce says, "True we are driven sometimes in science to try the suggestions of instincts; but we only try them, we compare them with experience, we hold ourselves ready to throw them overboard at a moment’s notice from experience."[10] Ironically, even though Peirce was asked by James to talk about things of Vital Importance in his 1898 Cambridge Lectures, Peirce insisted in his lecture that things of Vital Importance are not relevant to theoretical reason or science. But why is it so important to maintain this distinction between reason and sentiment?

First, Peirce believed that Metaphysics was an abstract science and thus required theoretical reasoning. As a consequence, sentiments and instincts had no place in philosophical thought. Second, it is very easy to confuse and mingle sentiments and reason. Peirce realized the powerful influence human sentiments and instincts have in human affairs. Indeed, he says, "It is the instincts, the sentiments, that make the substance of the soul. Cognition is only its surface. Its locus of contact with what is external to it."[11]  In addition, the need to act on vital issues concerning practical matters along with our egotistical nature to believe that we are acting from reason produces fertile ground for self-deception.  Therefore, the confusion between practical reasoning and theoretical reasoning may not be one that a person is conscious of.

Men many times fancy they act from reason when, in point of fact, the reasons they attribute to themselves are nothing but excuses which unconscious instinct invents to satisfy the teasing "whys" of the ego. The extent of this delusion is such as to render philosophical rationalism a farce.[12]


Let us grant Peirce the foregoing description of the human condition. Let us grant him that sentiments and instincts should not get involved in scientific matters and that the conduct of everyday life is probably best handled by sentiments and instincts. The question remains why is this distinction so crucial to Peirce’s Highest Maxim of Logic, namely, to want to learn the truth? Or, in other words, why is the mingling of theoretical reasoning and practical reasoning a roadblock in the path of inquiry?

            Peirce claims that belief does not pertain to scientific thought but only to practical thought.  Belief has three properties, according to Peirce:  "first, it is something we are aware of; second, it appeases the irritation of doubt; and, third, it involves the establishment in our nature of a rule of action, or, say for short, a habit."[13]  Peirce explains, "our beliefs guide our desires and shape our actions."[14] Thus, "We belief the proposition we are ready to act upon. Full belief is willingness to act upon the proposition in vital crisis, opinion is willingness to act upon it in relatively insignificant affairs." [15] If actions are connected to beliefs and if beliefs do not pertain to scientific thought but only practical thought, then science must have nothing to do with actions. This is Peirce’s conclusion: "But pure science has nothing at all to do with action."[16] The notion that science has nothing to do with action may seem startling, however, Peirce’s intentions need further clarification. 

The proposition it [science] accepts, it merely writes in the list of premises it proposes to use. Nothing is vital for science; nothing can be. Its accepted propositions, therefore, are but opinions, at most; and the whole list is provisional. The scientific man is not in the least wedded to his conclusions. He risks nothing upon them. He stands ready to abandon one or all as soon as experience opposes them.  … There is thus no proposition at all in science which answers to the conception of belief.[17]   


Peirce claims that scientific inquiry never reaches an absolute stopping point, since in science we never arrive at full belief.  Instead, all true scientific conclusions are open to questioning and their falsity is always a possibility. Science or the attitude of "wanting to learn the truth" requires that one always be in a questioning posture.[18]

I have argued that the foundation of the method science, according to Peirce, consists in simply "to want to learn the truth." I have also argued that this is the highest maxim of logic.  Even if my arguments are correct and we accept the foregoing conclusions, it still needs to be spelled out why they lead to the conclusion that the method of science is incompatible with Christianity. Why can’t a devout Christian be a true scientist or philosopher?   

3. The incompatibility of the Scientific Spirit and Christianity    


            Peirce believes that some forms of religion and/or Christianity are compatible with science. On the other hand, he also believes that some are not.   Since I argue that it is impossible that the same person be both a Christian and a scientist (or philosopher), it is necessary that I define the Christian person. To differentiate between the Christian person whose religiosity is reconcilable with the scientific method and the Chrsitian person whose religiosity is not, I will refer to them as the "Christian thinker" and the "Christian believer," respectively. 

3.1 The Christian Believer

            Who is the Christian believer whose religiosity is an obstacle to the road of inquiry? What is the form of religiosity that precludes the Christian believer from engaging in the scientific method? The Christian believer is one who has come to belief in the existence of God through either a scientific method or a non-scientific route and holds on to the truth of that belief at all cost. It is irrelevant whether the Christian believer has come to the belief in God through rational argumentation or faith; instead, what is important is the tenacity with which the Christian believer sustains the belief.  Thus, a person that believes in God and adamantly clings to the belief is the Christian believer.  The Christian believer, therefore, is not willing to give up her belief even if a critical assessment of the evidence for the truth of the belief would warrant her to do so. For the Chriatian believer, the possibility that God does not exist can never be a part of his or her contemplations. The Christian believer’s faith is so unshakable that the possibility of unfaith never enters his or her mind. The problem of the existence of God is never a real problem for the Christian believer. This assessment of religious beliefs and religious faith is not meant to be a negative one; instead it is meant as an accurate assessment of the inherent nature of many Christian’s belief in a personal savior and creator who loves His creation. Why are there Christian believers? 

Religious beliefs are not ordinary beliefs insofar as they implicate a radical and substantial personal commitment on the part of the believer. The radical and substantial commitment Christians have for the belief in God is evident in three elements that accompany this belief. The first element that accompanies religious beliefs is the act of worshipping on the part of the believer. Indeed, it is not simply that Christians believe that God exists, they also worship Him. They conceive of God as a being worthy of worship and thus as all-powerful, all-knowing, perfectly moral, and the loving creator of the universe. Compare this with the belief in the Big Bang Theory. The content of the latter belief does not lend itself in the way the belief in God does for worshipping. Indeed, there are view temples in honor of the Big Bang. The second element that accompanies the belief in God is that it implicates an entire way of life.  The belief in God, therefore, is not an isolated belief, but one that permeates a person’s heart and soul and embraces the most intimate details of his way of thinking and living. It is a belief that extends into a moral theory that ethically binds the believer. The third element that accompanies the belief in God is that salvation is embodied in the belief. Thus, the hope for eternal and everlasting happiness creates a momentous personal interest in the truth of the belief in God.  These three elements that accompany religious belief give some insight as to why there are Christian believers, i.e. why there are Christians who would do anything to protect and defend their belief from refutation. 


        I have argued that, according to Peirce, science and metaphysics should be pursued through theoretical reasoning alone. Peirce argued that practical reasoning, or thought guided by the sentiments and instincts, had no place (with the exception of positing hypothesis) in scientific research. The main reason for the exclusion of practical reasoning from science is because practical reasoning blocks the road of inquiry and this violates the scientific spirit and the highest maxim of logic. Therefore, contra William James, Peirce argues that the scientific person should never, under any circumstances, will a belief. Instead, the scientific person, when doing science, should not have full beliefs concerning the research in question; she should be open to all possibilities and be ready to go where the evidence leads.  According to Peirce, the scientific person exhibits the scientific spirit only if her personal interests are detached from the issues and/or possible conclusions being considered to the extent that the evidence can have a real effect on her belief forming process.  Thus, the scientific person never acquires full belief, let alone an unwavering and unshakable full belief, but rather all opinions are open to temporary status and he or she should be willing to throw them out as soon as evidence to the contrary is made available. This conduct is impossible for the Christian believer, who practices a common version of religiosity in which faith in God can be interpreted as an unwavering and unshakable full belief in the existence of God and all of the Christian doctrine provided by revelation. Is the concept, therefore, of a "scientific-theologian" an oxymoron? That Peirce answered the latter in the positive is easy to illustrate. He says:  

In my opinion, the present infantile condition of philosophy, – for as long as earnest and industrious students of it are able to come to agreement upon scarce a single principle, I do not see how it can be considered as otherwise than in its infancy, - is due to the fact that during this century it has chiefly been pursued by men who have not been nurtured in dissecting-rooms and other laboratories, and who consequently have not been animated by the true scientific Eros, but who have on the contrary come from theological seminaries, and have consequently been inflamed with a desire to amend the lives of themselves and others, a spirit no doubt more important than the love of science for men in average situations, but radically unfitting them for the task of scientific investigation.[19]





[1] CP [5.363]

[2] CP [6.428-6.434]

[3]  Charles S. Peirce, "Reason and the Logic of Things," 28.

[4] Peirce says: "Logic is itself a study of signs. Now a sign is a thing which represents a second thing to a third thing, the interpreting thought." Charles S. Peirce, "Reason and the Logic of Things," 146

[5] Peirce says: "Upon careful analysis, I found that all three triads [ that make up the principle part of Logic] embody the same three conceptions, which I call after Kant, my categories [Firstness, Secondness and Thirdness]." Charles S. Peirce, "Reason and the Logic of Things," 146.   

[6] Charles S. Peirce "Pragmatism as a Principle and Method of Right Thinking: The 1903 Harvard Lectures on Pragmatism"110.

[7] Charles S. Peirce, "Reason and the Logic of Things," 178.   

[8] Charles S. Peirce, "Reason and the Logic of Things," 109.   

[9] Charles S. Peirce, "Reason and the Logic of Things," 111-2.   

[10] Charles S. Peirce, "Reason and the Logic of Things," 112.   

[11] Charles S. Peirce, "Reason and the Logic of Things," 110.   

[12] Charles S. Peirce, "Reason and the Logic of Things," 111.

[13] In "The Fixation of Belief" he provides a similar definition of Belief: "the feeling of believing is a more or less indication of there being established in our nature some habit which will determine our actions." [5.371].

[14] [5.371]

[15] Charles S. Peirce, "Reason and the Logic of Things," 112.   

[16] Charles S. Peirce, "Reason and the Logic of Things," 112.   

[17] Charles S. Peirce, "Reason and the Logic of Things," 112.   

[18] The implications of Peirce’s view for philosophy of religion are controversial. According to Peirce’s view, if faith implies full belief, then a person of faith could never be a philosopher.  

[19] Charles S. Peirce, "Reason and the Logic of Things," 107-8.