Let’s call B(p) the set of all beliefs a person p holds. We can denote S(B(p)) as the subset of beliefs held by p for which they can provide a scientific justification, and NS(B(p)) as the set B(p) minus S(B(p)). Can p be said to be epistemologically self-consistent if both S(B(p)) and NS(B(p)) are non-empty?

More colloquially, is it legitimate for a person to hold some beliefs justified by science while simultaneously holding other beliefs not derived through the scientific method?

For example, Blaise Pascal contributed to many justified beliefs using the scientific method in fields like fluid dynamics. However, Pascal is also well-known for his wager and for the phrase "The heart has its reasons which reason does not know" (related), both reflecting his belief in God, which certainly was not justified through scientific means.

A more recent example might be Francis Collins, a renowned "American physician-scientist who discovered the genes associated with several diseases and led the Human Genome Project." He also wrote the book The Language of God: A Scientist Presents Evidence for Belief, which argues for Christian theism using points beyond the purview of science, such as the argument from morality.

Is it epistemologically self-consistent for a person to use the scientific method to justify some of their beliefs and rely on non-scientific justifications (or no justification at all) for others?

And if it is, how can we determine which method of justification is the right one to be used for any given specific belief?

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    The idea that science can be used to solve every problem was given up half a century ago by almost all serious thinkers. It was never a well-justified position. Commented Jun 15 at 15:45
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    Probably most all beliefs humans have or have ever had have not been justified scientifically. Probably the vast majority of beliefs are either unconscious or people are only somewhat conscious of. If you want to justify something, you need to know exactly what it is you believe, and use a method that provably gets a result that you will attest to. Otherwise, seeking justification is not... Justified. Any method that provably gets a result is perfectly ok. But what is proof? Probably that it yields consistent results, not just for yourself, but for others you trust more than yourself (?)
    – Scott Rowe
    Commented Jun 15 at 16:39
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    @tkruse See the comments below
    – Rushi
    Commented Jun 16 at 6:10
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    The scientific method is the wrong tool to use to justify beliefs.
    – Neil_UK
    Commented Jun 16 at 12:49
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    @Neil_UK Is belief in gravity justified? Is my belief in the existence of my hands justified?
    – user66156
    Commented Jun 16 at 17:58

6 Answers 6


You begin your question with the term 'epistemological self-consistency'. I believe that such a term simply reduces to rationality, thus we can re-write, particularly paraphrasing the latter half of the question:

Is it rational to use other forms of justification besides scientific justification?

The answer is an unqualified yes. It is absolutely rational to be pluralistic in one's application of justificatory methods. It makes a lot of sense to perform mathematical justification in the domain of mathematics, scientific justification in the domain of science, economic justification in the domain of economics, etc. This naturally carries to the logical end that it makes sense to use religious justification in the domain of religion, a topic you seem highly interested in reconciling with contemporary philosophical thinking.

The real thrust of your question is, if the epistemological success of science is so irrefutable, then shouldn't it essentially be applied to all domains of discourse? Here, you have broached the central concern of what constitutes the thinking of scientism. From WP:

Scientism is the view that science and the scientific method are the best or only way to render truth about the world and reality... While the term was defined originally to mean "methods and attitudes typical of or attributed to natural scientists", some scholars, as well as political and religious leaders, have also adopted it as a pejorative term with the meaning "an exaggerated trust in the efficacy of the methods of natural science applied to all areas of investigation (as in philosophy, the social sciences, and the humanities)".

Here then we have a serious metaphysical issue; to what extent should science predominate our thinking? That answer varies by thinker, and as a quietist, I don't believe that any metaphysical position is inherently logically superior to another; rather, one gravitates towards the answer that benefits one on a deeper emotional level in the same way that Ayer's non-cognitive emotivism interprets ethical theorizing as a Wittgensteinian language-game played on top of a series of boo's and yay's about elemental questions.

However the answer to your question has a straightforward response itself because rationality is understood and can be explained and defended in a broad, epistemological manner consistent with goal-oriented truisms. If we take a broad theory of rationality to encompass the position that human rationality is both bounded (SEP) and instrumental (SEP), then what we are saying is that human beings are not rational calculators in the spirit of Homo economicus, but rather are limited, sometimes conflicted agents who have often conflicting priorities and beliefs. Many aspirant philosophers have a deep-seated belief that they are the former, but any amount of life experience aided by some horse sense invalidates such a belief.

Thus, there is nothing irrational about segregating one's beliefs about the physical universe such that they require scientific justification apart from one's mental and spiritual life using another means, such as natural theology. This point of having broadly distinct philosophical domains for fact and value had a defender in the person of Stephen Jay Gould who posited they existed as non-overlapping domains of magisteria which presupposes that scientific justification is not the only form of worthwhile justification.

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    TIL I am a Quietist. Finally, a name for how I tend to function! Thank you.
    – Scott Rowe
    Commented Jun 16 at 19:16
  • Gould's advice is good, but there is a problem that Gould's "Non-Overlapping Magisterium" claim is explicitly false. There is significant overlap between science and religion, between different sciences, and between bot science and religion and various non-science disciplines like math and history. Pluralism is -- something we need to accept. But it is better when the justifications for pluralism are not clearly false.
    – Dcleve
    Commented Jun 17 at 20:49
  • @Dcleve I understand your point, but systems of semantics should be held to accurate or inaccurate, valuable or invaluable, and precise or imprecise according to their utility with respect to the purpose of the user, at least if one understands pluralism fully. It's ironic to claim we need to accept pluralism, but then reject a member of the plurality, especially one which many people find useful. ; )
    – J D
    Commented Jun 17 at 21:46

Assertion: I probably ought not leave the Mona Lisa in the middle of a busy road.

This is a claim I have never subjected to direct experiment. Indeed, it is a hypothesis I never intend to test. Even so, I have elevated it to the level of belief. I wouldn't say that's irrational.

I was originally going to respond to your question with "Yes: mathematics." After all, calculating the integral of a function is not done by experiment but by pure logical inference. The notion that there is a special category of a priori knowledge which transcends the physical world is as old as Aristotle. However, it seemed worth going a step outside pure logic and into reasonable everyday beliefs.

If you asked me to justify my assertion at the start, I could say something about hard sciences like the amount of momentum in the typical car. I could say something about softer sciences, like the psychology of drivers' attentiveness. I would need to draw on logic and mathematics to link things up and ground that word "probably". I would need some sort of aesthetic and historic disciplines to explain why the Mona Lisa differs in significance from a toddler's crayon scribbles. I would also need to draw on some sort of metaphysical axioms to ground that "should", recognising David Hume famously argued that "you cannot derive an ought from an is".

All that is to say, there are many fields of study which do not readily lend themselves to the scientific method. We can and do validly draw on many of them together to make richer sense of the world and our place in it.

You focused your question on scientists talking about religion, so I'll leave just one comment specific to your examples. Although it can be valid for one person to think scientifically in one case and more metaphysically in another, that doesn't mean they're automatically any sort of authority in both. As you say, Francis Collins is a renowned scientist. For balance, I'll suggest we add Richard Dawkins to that camp. Both have written books which strayed from Science into Philosophy of Religion, albeit with famously different positions. They're allowed to do that. Still, they could also either, or both, be wrong.

  • When two people make contradictory assertions, I tend to say that they are both wrong. A correctly stated case should be convincing. Keep trying until you convince the other, and everyone (who is sane). Short of that, "I don't know" is the answer.
    – Scott Rowe
    Commented Jun 16 at 12:32
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    @ScottRowe They actually debated each other once, without managing to change each other's mind: Richard Dawkins & Francis Collins: Biology, Belief and Covid
    – user66156
    Commented Jun 16 at 15:40
  • +1 "Yes, mathematics".
    – J D
    Commented Jun 16 at 17:32

It's not necessarily inconsistent to have beliefs justified by different methods. It's part of the human condition that life sometimes requires to make decisions based on beliefs which cannot be based in the scientific method.

As an example several forms of body-mind dualism hold that mind is something real which persons experience but which has aspects defying scientific analysis (qualia), while body being something utterly scientifically understandable.

It is epistemologically invalid to cherry-pick justifications to satisfy some personal convictions, there must be some objective standars foe when to all which method, else no 2 people would be able to agree on anything. There may be various such standards though.

To make matters simpler, in modern times writers are expected to keep writings on science and writings on non-science separate, so no discussions on where to draw the line would be necessary.


Is it consistent? It depends...

One would need to address consistency on a method-by-method basis. But if we're talking about the general principle:

If one uses the scientific method for some S but not NS, a consistency objection could potentially take the form of one or more of the following:

  • The scientific method can reasonably be used for NS but it isn't being used, and there's no good differentiating criteria that justifies using it for S but not NS.

    One might consider "alternative medicine" as an example: we can scientifically test the efficacy of some medicine, so if someone holds that some medicine is effective despite science failing to support that, that might be inconsistent. Although alternative medicine proponents may not generally explicitly stand by the scientific method for other things, in which case there may be a bigger discussion there about what inconsistency exists there, or how their position is otherwise unreasonable.

    One could also consider that we can scientifically investigate some underlying basis of NS. For example, our investigation might demonstrate that dreams in general lack objective truth value, which would undermine someone saying a dream supports NS.

  • The NS method can reach a conclusion about S that's different from the conclusion reached through the scientific method.

    In this case, one might say there's a conflict or an inconsistency in trusting both the NS method and the scientific method.

    This is very similar to the first point, but it just flips it around.

  • The NS method might be inconsistent independent of the scientific method.

    For example, someone might hold up some religious text to support their own religious belief, in which case one might point to someone with a contradictory religious belief using comparable evidence to support their belief. They may be inconsistent to use that as justification for their belief without accepting that as justification for beliefs they reject, and this also points to potential unreliability of the method (which is closely related to consistency).

  • The NS method could also be bad for some other reason, of course. This reason doesn't necessarily need to invoke consistency (although one might argue that just about every logical fallacy ultimately boils down to consistency, and at least my own objections to other epistemologies tend to relate to consistency, and thereby reliability).

Which method of justification is "the right one" to evaluate any given claim?

Well, that would be a question for anyone who wants to have multiple methods that can be applied to the same claim. They would need a justification for using one method above the other, otherwise their choice could be considered arbitrary and thus likely inconsistent.

Side note: The argument from morality

You mentioned the argument from morality for God's existence. I wouldn't directly argue about consistency there, but rather:

  • That tends to boil down to wishful thinking (or fallaciously appealing to consequences): saying God exists because you dislike the consequences of God's non-existence, which would entail the non-existence of objective morality. (Some people make a positive case that objective morality exists, rather than just claiming that it does, but I haven't found any such argument to be compelling nor consistent with demonstrable reality.)
  • Objective morality arguably doesn't exist even if God exists (since God's morality is still mind dependent, therefore subjective).
  • The mere existence of a person's sense of morality is better explained by evolution and social or environmental influences. Theism tends to just assert that it accounts for morality, which isn't much of an explanation, and doesn't explain the method by which this happens and the theist claim isn't backed up by good evidence.
  • The reality of morality tends to be more of a problem for theism: there are very different views on what people think are right and wrong, which could be considered incompatible with the existence of an all-powerful being who wants us to follow certain rules.

Related: According to atheistic/agnostic worldviews, what is the basis for morality?

Side note 2: Pascal's wager

As for Pascal's wager, that has a fair amount of criticism, and the general idea of basing beliefs on what your heart says certainly has consistency problems. You can wish with all your heart that you have a million dollars in your bank account, but that doesn't say much about whether it's true. Most people would ultimately use reliable empirical and rational means to come to a belief about how much money they have in their account, and that might point to an issue of consistency if they are using their heart for some beliefs.

  • @Mark Well, how I get to trusting science in the first place is because it's built on principles of reliability/coherence, parsimony and explanatory and predictive power, and those are certainly principles I try to apply consistently throughout my epistemology, whether I'm evaluating things using the scientific method or not.
    – NotThatGuy
    Commented Jun 16 at 0:35

I would argue that it may be "possible" (or, rather, "non-problematic") in some cases, but that, as a general and practical consideration, no, it's not consistent.
Or, rather, it's not consistent to do that, for a given level of stakes in justifying the various beliefs in question.

Let me explain.

Because of reality, even the most deluded of people should have an intuitive understanding that there are things which are "true", and things which are not "true". Most of people would get familiar with this when reality places them in situation that they don't like. Ex: as a child, you fall down, and you get hurt. It's unpleasant. You'd rather not experience that. And yet you do. Clearly there is something out there, independent from you and from your preferences, that impacts you, whether you like it or not. You may decide to deny it, but if you do, sooner or later reality will catch up, and something bad will happen to you. Because of that, it was useful as far as evolution is concerned to develop a concept of truth, and to use it adequately to survive and thrive.
With that, we may define "truth" (at least in the frame of this discussion) as the property of a world model such that it allows to properly represent and make accurate prediction regarding reality. Also, practically speaking, one way to be able to say that something is true is if it can be observed / measured independently from the observer and their own preferences.

So here we see that everyone (unless they are intellectually impaired maybe) should have an understanding a what "truth". Notably, "truth" is what allows them to navigate reality in order to achieve their goal and try to maximize their interest (or at least strive to do things or activities which ultimately "feel good"). That's why people don't like to be deceived. They understand, at least intuitively, that doing this to them causes them some kind of harm, insofar as it prevents them from achieving their goal, or from doing it optimally.
That's where we introduce the concept of stakes. The "level of harm" caused in the situation described above depends on how important it was for the person to achieve the goal in question. Lying to you about the schedule of the ice cream truck is "less bad" than accusing you of a serious crime that you did not commit in froint of a jury, because in the former case, the stakes are just the ability to get a sweet treat and the associated small pleasure, whereas in the latter case, the stakes are your ability to still spend your life as a free person, outside of prison (the stakes being here proportional to the number of years that you'd spend in jail if found guilty).
That's why truth, and establishing it properly, is so important in judicial matters, because the stakes of not punishing an innocent person, or to punish a guilty person only with a proportionate penalty, carry a lot of weight for the recipient.

So at this point we have defined a concept of truth, and a concept of stakes related to taking decision (based on beliefs).
Now, it should be easy for most people to understand that taking a decision based on a belief that is not true may lead to harm being caused to someone else, right?
Let's make the reasonable assumption that people don't like it when something bad happens to them or when they pay an opportunity cost (being prevented from achieving their goal) because someone took a decision based on a belief that is false (let's put aside for now the consideration that sometimes it's just very hard to know whether something is true or not / things may be uncertain, yet a decision must be taken). Ex: being falsely accused of murder.
Then, it seems like people should find it reasonable to decide that one of rules that needs to be followed when living in a society (as soon as there are two people or more) is that one should not do this (take a non-justified, harmful-for-someone-else decision), right? Of course, in practice, the application of this kind of "non-harm" rule is still subject to the balance between it and the individual stakes of the people. For instance, though I would still not like it, I would understand if someone were to falsely accuse me of murder, if the alternative for them was being killed by the real bad guy. The stakes for them (their own life) is in balance with, or even heavier than, the harm that they may cause to me.
Of course, such a rule is derived from an important axiom: the one that says that nobody is special, and so that the desire for people to "do what they want", and to be protected from adversity, is worth the same level of respect and consideration.

But then, why would people hold beliefs which they don't know are true in the first place? Well, there can be a lot of reasons.
Because it's convenient for them.
Because it makes them feel good.
Because they built their identity around it (and may not have had any choice in the matter in some cases, e.g. children).
Or maybe because it has never been important enough for them to validate or disprove properly (<=> because the stakes associated to that belief have never been high). After all, sometimes it hard to determine whether something is true or not, so it's understandable to hold some things for tentatively true until the times comes when it becomes important.

So then, we have seen / we can assume that:

  • People can hold beliefs which are not true.
  • People can harm other people by holding as true beliefs which are not.
  • People don't like to be harmed in general, and in particular in that specific way.
  • People can understand when one harms someone else, when the stakes for one is high enough, as long as the interests of everyone stay in balance.

So it follows that it's inconsistent to "hold for true a belief without enough justification with regards to the harm that may come to someone else from taking a decision based on that belief".

In more details, it's "fine" for one to believe in a supernatural being without reasonable evidence, as long as one does not make it someone else's problem, or, in general, as long as one does not create stakes for other people out of that yet-to-be-justified belief.

But I would argue that, for a non-negligible (or very vocal) proportion of the population, it's hard to do that, and sometimes they don't even care. For them, at least one of the hypotheses / considerations described above does not apply.
Maybe they consider themselves more important than other people, and that their interests trump that of other people (=> unbalance between their own interests and that of some other people, and less beholden to properly justifying their own beliefs compared to what they would ask other people to do if the roles were reversed). Maybe they lack the ability to put themselves in other people's shoes, in order to properly evaluate the balance of interests.
Or maybe they underestimate the potential of harm to other people associated to holding a belief as true when it's false or when it has not been demonstrated enough to be true.
Or maybe they are just wrong / deluded, and they let their own preferences impair their ability to reason regarding the topic which is the object of the belief.

So, to answer your questions:

  • Given the importance of truth in order survive, strive, and achieve one's own goal, coupled with the need for people to live in society, and the understanding that no one is special, then no, it's not consistent.
  • However, achieving truth is sometimes hard, so in practice it's understandable and "fine" to not do it, as long as the stakes are low.
  • So, to use your words, the choice of the "method of justification" depends on the level of the stakes in achieving the truth for people who will be impacted by a decision taken based on the belief that is the object of the justification. I'd say that one way to evaluate this level is to try to put ourselves in the shoes of those people, and to actually ask them what those stakes are for them.
  • Very nicely worded and argued! Regarding proportionality, fairness and justice: "With what measure ye mete, it shall be measured to ye again."
    – Scott Rowe
    Commented Jun 18 at 23:28
  • Thank you : ) And yeah, that's basically it! Commented Jun 19 at 21:40

Not really.

Science doesn't lead to beliefs.

Science leads to informed, supportable, repeatable/reproducible coherent conclusions.

Beliefs are not typically conclusions, but instead are typically founded by or invoke leaps of faith. A choice to believe.

Some will argue the point... but it is fact that one can live with zero beliefs.

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    "Look before you leap."
    – Scott Rowe
    Commented Jun 18 at 23:34

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