It is sometimes claimed we all must begin our investigation of the world with assumptions held with full certainty, often called “presuppositions”. These presuppositions are not based on evidence, but are claimed by many to be necessary untested axiomatic notions without which we can not make sense of the world. We must just accept them before any inquiry about the world can get off the ground. The list of alleged necessary presuppositions varies from person to person, but they often include the following:
- The infallibility of logic
- The infallibility of mathematics
- The comprehensibility of an actual world
- The reliability of our minds
- The accurate reflection of an actual world by our senses
- The continued efficacy of induction
What do you think? Must we accept without evidence these axiomatic notions before we can explore our reality? And is accepting anything without evidence such as these allegedly necessary presuppositions rational?
The answers are “no” and “no” We do not need to accept anything as a given before exploring our world. And full epistemic confidence in any notion that deviates from the degree of the evidence is always irrational.
Let’s explore this in depth.
We can imagine scientists prior to Einstein accepting with absolute confidence that time and space were immutable constants. Was this absolute confidence warranted? No. Why not? The familiarity scientists had with time and space was based on induction. In their experience, the constants of time and space had never been violated. But that inductive experience with time and space does not warrant absolute confidence. High regularity warrants only high confidence, and high confidence is qualitatively different from absolute confidence. Absolute confidence is something for omniscient minds (should they exist) who need not inductively assess notions such as time and space. Human minds can not escape their subjectivity, and therefore are confined to inductive assessments for everything apart from their immediate sensations. The scientists who accepted the constants of space and time as absolute presuppositions were irrational. Their absolute certainty prevented them from imagining space and time as relative as Einstein revealed.
What is the lesson learned from these irrational scientists holding as immutable presuppositions the constants of time and space? Less-than-omniscient minds must rely on induction in any assessment of their external realities, and induction never reaches absolute evidential certainty. And where there is no absolute evidential certainty, there can be no rational epistemic certainty.
Imagine these irrational scientists holding as immutable the constants of time and space arguing that, if we can not have absolute confidence in measurements of time and distance, we can not do science. We have since discovered that this quite intuitive notion is simply untrue. We have been able to arrive at even more precise measurements of physical phenomena now that we accept the relativity of time and space.
Imagine these irrational scientists claiming that, since we can not imagine a world in which time and space was not immutable, we are justified in placing absolute confidence in their immutability. Would this argument get them off the hook for irrationality? No. Their familiarity with time and space was based on induction, and their lack of imagination or understanding does not magically justify accepting the immutability of time and space as a presupposition. Only a high degree of certainty that time and space is immutable, arrived at through induction, was warranted prior to Einstein’s seminal paper. There were perhaps many capable scientists who, had they not presupposed the immutability of time and space, could have also arrived at the notion of relativity prior to Einstein.
The relevant point is, human minds have no business accepting anything with full certainty. Accepting anything as a axiomatic epistemic presupposition is irrational.
But what about logic or mathematics? Are we not justified in placing absolute certainty in their continued efficacy? No. From the time we was born, few of us have experienced a violation of logic and mathematics. Does this inductive assessment with zero violations warrant absolute epistemic certainty? No inductive assessment warrants absolute epistemic certainty. It must remain a less-than-absolute high degree of confidence.
But we can’t begin to imagine what a violation of logic or mathematics would look like, some might respond. That’s irrelevant. The fact that pre-Einstein scientists could not imagine a violation of absolute time and space did not warrant a presupposition. Neither does our lack of imagination or understanding warrant an absolute presupposition in the inviolability of logic and mathematics.
The suggestion that the comprehensibility of our reality is a necessary presupposition prior to exploring our world is more easily shown false. The universe has no obligation to make itself comprehensible. If no regularities appear to a particular mind, that mind simply can not abstract facts about the nature and composition of the reality it finds itself exploring. What is not justified is for that mind to presume the universe must necessarily be comprehensible. Such a presupposition is intrinsically irrational.
What about the reliability of our minds. Must we not start with the presupposition that our minds are reliable prior to exploring our reality? Once again, no. Even those who claim they presume their minds are reliable admit their minds were quite unreliable when they were infants, and will again become unreliable when they are old. How will they determine their minds’ degree of reliability? By finding a passage of scripture that outputs the degree of cognitive reliability for a particular age? No. They will inductively assess how forgetful they have become, and how capable their cognitive functions currently are at accomplishing their daily objectives. Presuming the reliability of your mind is both foolhardy and irrational.
What about the notion that the regularities we perceive reflect an actual external world. Surely we can presume this, right? No. We still have not been gifted omniscience, and we are therefore still dependent upon our inductive exploration of our reality. We could be dreaming or hallucinating our reality, but that possibility does not justify abandoning rationality and presuming that we are not dreaming or hallucinating. For as long as our apparent decisions in our apparent reality accomplish our apparent desires, we are warranted in a high sub-absolute degree of confidence there is something substantive about that apparent reality. But presuppositions are not justified.
But are we not guilty of circularity since we have presumed the absolute and eternal reliability of induction as foundational to our epistemology? We have not presumed the absolute and eternal reliability of induction. Rationality, at its very basic is following what works. We have goals, and we are rational when we employ what we perceive to work to accomplish those goals. Induction seems to be a very reliable way to determine what will work in the future by assessing what has worked in the past. Does this not mean we must place absolute confidence in the continued reliability of induction? No. That is neither necessary nor rational, our inability to conceive of a failure of induction notwithstanding. If some newly-found epistemic method were to accomplish our goals better than our inductive assessment of our reality, then it would be irrational not to replace the inductive method with that new method. And the simple fact that we can not imagine what a failure of induction might look like will never justify a presupposition that induction will never fail.
In summary, epistemic humility requires the subjective mind to reject all proposed presuppositions, and to simply inductively map epistemic certainty to evidential certainty. Invariance in logic and mathematics does not warrant a presupposition. This invariance merely warrants a high sub-absolute degree of confidence that maps to the degree of that invariance. The difference between a presupposition and a high sub-absolute degree of certainty is not insignificant. It is a difference that allowed Einstein to conceive of a new paradigm that more accurately reflects our reality.
Some Christian leaders suggest Christians are justified in presupposing the infallibility of the Bible and the existence of God. Why would anyone neglect their epistemic responsibilities and accept the Bible or God as presuppositions immune to the scrutiny of rational inquiry? Doing so would (and does) protect the Christian perspective from criticism, but this is no virtue. Both the Bible and the Christian notion of God are testable, and to accept these as presuppositions off-limits to assessment and reassessment is precisely opposite what an honest seeker would do.
This suggestion by some Christian leaders that we may justifiably accept God and the Bible as presuppositions immune to assessment and reassessment can not be more misguided. To default to presuppositions is to forfeit the standing of an honest seeker.