PHIL 3120: American Philosophy
Dr. Robert Lane
Lecture Notes: Tuesday January 15, 2013


[2.1.4.] Against Individual Certainty.


C2. “the ultimate test of certainty is to be found in the individual consciousness.”


Descartes employed “clearness and distinctness” as a standard of certainty. On his view, any belief that is clear and distinct is epistemically certain (i.e., anyone who believes it cannot be wrong about it). And whether or not a belief is clear and distinct for an individual can reliably be judged by that very individual.


For example, when I reflect on my own thoughts and on my own existence, my belief that I am thinking and my belief that I exist appear to me as being clear and distinct. I am in a unique position to judge whether my own beliefs are clear and distinct and therefore to judge whether they are epistemically certain. And you are in the same position with regard to your beliefs. So on Descartes’ approach, each individual is capable of seeing for herself whether her own belief is certain. Peirce expresses this idea as: “Whatever I am clearly convinced of is true.” (71)


But he continues: “If I were really convinced, I should have done with reasoning and should require no test of certainty.” (71) In other words, if you genuinely believe something, then you would not be sincerely motivated to investigate whether it is (not just true but) epistemically certain. It’s almost as if he is saying: when a person really believes something, he does not bother checking to see how well-supported his belief is. A sincere belief is one that is settled—the believer is no longer motivated to look for evidence or reasons to support it. [In the next reading, we will see Peirce explain his concept of belief at greater length.]


Peirce goes on to assert that “to make single individuals absolute judges of truth is most pernicious.”


pernicious (df.): destructive; tending to cause great harm.


Why, on Peirce’s view, is Descartes’ standard of clearness and distinctness pernicious? It is pernicious for inquiry, and especially philosophical inquiry.


If each individual is the absolute judge of what is true, then there is no need to pay attention to the results of others’ inquiry, even when they disagree with you. When individual inquirers, such as philosophers, are intellectually isolated from each other, each caring nothing about the opinions of others, even when those opinions diverge dramatically from their own, there is no hope that agreement among those individuals will ever be reached.


By employing the Cartesian criterion, philosophers have failed to achieve the consensus (df.:  general agreement; unanimity) that is frequently reached in the physical sciences:


[M]etaphysicians will all agree that metaphysics has reached a pitch of certainty far beyond that of the physical sciences;—only they can agree upon nothing else. In sciences in which men come to agreement, when a theory has been broached it is considered to be on probation until this agreement is reached. After it is reached, the question of certainty becomes an idle one, because there is no one left who doubts it. We individually cannot reasonably hope to attain the ultimate philosophy which we pursue; we can only seek it, therefore, for the community of philosophers. (71)


And so here is the claim with which Peirce replaces C2:


P2. “...We individually cannot reasonably hope to attain the ultimate philosophy which we pursue; we can only seek it, therefore, for the community of philosophers.”


This passage suggests that progress in philosophy can happen only if individual philosophers begin to collaborate with each other the way that scientists do: sharing their results, taking account of the previous findings of others, noting when those findings disagree with one’s own, etc. No one philosopher, working in complete isolation from others, can build a complete philosophical system, any more than a single physicist could, on her own, arrive at a complete account of the physical universe.



[] Against Certainty, Period.


Lurking behind C2 is Descartes’ assumption that epistemic certainty is attainable.


Peirce’s view was that we will never attain the certain beliefs that Descartes sought. Even if it were possible voluntarily to doubt everything, this would not help us identify a set of certain beliefs.


Rather than the “pretend doubt” that (according to Peirce) Descartes adopted in his quest for certainty, Peirce advocates...


fallibilism (df.): the view that any belief, no matter how fundamental or seemingly secure, might turn out to be false.[1]


On Peirce’s view, no belief is ever beyond revision, and there is no such thing as (epistemic) certainty.[2]


In short, Peirce rejects two assumptions made by Descartes:

1.      that individual inquirers can attain epistemic certainty, and

2.      that epistemic certainty is possible for human inquirers at all, whether they are acting alone or in collaboration.

But in doing so he does not give up the belief that we can discover things about the world. Human inquiry is never guaranteed to be perfect, but it is frequently successful—it does frequently result in true beliefs.



[2.1.5.] Chain vs. Cable.


C3. In philosophy, it is acceptable to support claims with “a single thread of inference depending upon inconspicuous premises.”


P3. Philosophy should “proceed only from tangible premises which can be subjected to careful scrutiny, and ... trust to the multitude and variety of its arguments than to the conclusiveness of any one.”


Peirce is making two claims here:


The first claim is that the premises in philosophical arguments need to be clearly stated so as to be subject to careful examination. This is a sensible piece of advice not only for philosophy but for any area of inquiry.


The second claim is a bit more complicated....


Philosophical reasoning should be less like a chain constructed from single links, one link connecting only with the previous and the next, and more like a cable woven from many different threads.

·         A claim that is supported by multiple arguments is more warranted than a claim supported by only a single argument, just as a scientific claim, e.g., that exposure to a certain chemical tends to cause cancer in humans, is better supported if multiple studies by different researchers in different laboratories reach that conclusion than if only a single study by only a single group of researchers does so.[3]

·         If a given claim is supported by only a single argument, then that claim is only as secure as the weakest step in that argument. And if that single argument turns out to be unsound, then the claim will lack support altogether. On the other hand, if that claim is supported by several distinct arguments, than the failure of one argument does not leave the claim completely without support. The claim may still be sufficiently supported by the remaining arguments.

·         An example of “the multiform argumentation of the middle ages” is the approach taken by the medieval theologian and philosopher St. Thomas Aquinas (1225-1274) to prove the existence of God. Aquinas did not rely on only a single proof but instead gave five arguments each of which purported to demonstrate that God exists.[4]


Peirce rejects Descartes’ attempt to prove his own existence, an attempt that we can represent as follows:


1. I am thinking.

2. Therefore, I exist.


Peirce suggests that instead of this single-link Cartesian chain, an individual might employ an exceedingly thick cable to support the claim that she herself exists.


Let us suppose ... that a dozen witnesses testify to an occurrence. Then my belief in that occurrence rests on the belief that each of those men is generally to be believed upon oath. Yet the fact testified to is made more certain than that any one of those men is generally to be believed. In the same way, to the developed mind of man, his own existence is supported by every other fact ...[5]


An argument for one’s own existence can be built using as premises every other fact of which one is aware. This would form an enormously thick cable, in contrast to the feeble thread by which Descartes’ belief in his own existence dangles.




Stopping point for Tuesday January 15. We will finish Peirce’s criticisms of Decartes at the beginning of the next class. For next time, read through the end of section IV of “The Fixation of Belief” (pp. 107-15).





[1] Peirce coined the term “fallibilism,” although the idea was not new with him. For more information on fallibilism, see Stephen Hetherington, “Fallibilism,” Internet Encyclopedia of Philosophy, URL = <>, accessed January 14, 2013.


Cf. James Rachels’ discussion of philosophy done with “risk” (in which one’s common-sense beliefs about morality and other topics can be overturned) vs. “safe” philosophy (e.g., Moorean insulation, in which common-sense can never be shown to be wrong by philosophical arguments), in Can Ethics Provide Answers? pp.1ff.


[2] In Peirce's words: “people cannot attain absolute certainty concerning questions of fact.” (CP 1.149, c.1897; not in your textbook) But the fact that we cannot start from certain premises, or arrive at certain conclusions, does not mean that inquiry itself is pointless: inquiry, to have that completely satisfactory result called demonstration, has only to start with propositions perfectly free from all actual doubt. If the premises are not in fact doubted at all, they cannot be more satisfactory than they are. (p.115, CP 5.376. EP 1:115)


[3] As Peirce said in a 1898 lecture he entitled “Training in Reasoning,” “[d]etached experiments, like detached thoughts or detached soldiers, are of little account. It is when they are massed into squads, and companies, and battalions, and regiments, and brigades, and divisions, and armies that they become strong and stronger.” (RLT 188)


[4] Summa Theologica Qn.2 Ar.3.


[5] “Questions Concerning Certain Faculties Claimed for Man,” CP 5.237; not in your textbook.

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