Asking whether a belief X is justified can lead to very opinion-based answers (e.g., Does life have a natural or supernatural origin?), but I don't think this necessarily has to be the case if we constrain the scope of the question to be answered from very specific epistemological theories of justification, namely, evidentialism and process reliabilism.

First, some definitions:


Evidentialism in epistemology is defined by the following thesis about epistemic justification:

(EVI) Person S is justified in believing proposition p at time t if and only if S’s evidence for p at t supports believing p.

As evidentialism is a thesis about epistemic justification, it is a thesis about what it takes for one to believe justifiably, or reasonably, in the sense thought to be necessary for knowledge. Particular versions of evidentialism can diverge in virtue of their providing different claims about what sorts of things count as evidence, what it is for one to have evidence, and what it is for one’s evidence to support believing a proposition. Thus, while (EVI) is often referred to as the theory of epistemic justification known as evidentialism, it is more accurately conceived as a kind of epistemic theory. In this light, (EVI) can be seen as the central, guiding thesis of evidentialism. All evidentialist theories conform to (EVI), but various divergent theories of evidentialism can be formulated.

Source: https://iep.utm.edu/evidentialism/

Process reliabilism

Reliabilism encompasses a broad range of epistemological theories that try to explain knowledge or justification in terms of the truth-conduciveness of the process by which an agent forms a true belief. Process reliabilism is the most common type of reliabilism. The simplest form of process reliabilism regarding knowledge of some proposition p implies that agent S knows that p if and only if S believes that p, p is true, and S’s belief that p is formed by a reliable process. A truth-conducive or reliable process is sometimes described as a belief-forming process that produces either mostly true beliefs or a high ratio of true to false beliefs. Process reliabilism regarding justification, rather than knowledge, says that S’s belief that p is justified if and only if S’s belief that p is formed by a reliable process. This article discusses process reliabilism, including its background, motivations, and well-known problems. Although the article primarily emphasizes justification, it also discusses knowledge, followed by brief descriptions of other versions of reliabilism such as proper function theory, agent and virtue reliabilism, and tracking theories.

Source: https://iep.utm.edu/reliabilism/


Abiogenesis is the natural process by which life arises from non-living matter, such as simple organic compounds. The prevailing scientific hypothesis is that the transition from non-living to living entities on Earth was not a single event, but a process of increasing complexity involving the formation of a habitable planet, the prebiotic synthesis of organic molecules, molecular self-replication, self-assembly, autocatalysis, and the emergence of cell membranes. The transition from non-life to life has never been observed experimentally, but many proposals have been made for different stages of the process.

Source: https://en.wikipedia.org/wiki/Abiogenesis

Is belief in abiogenesis justified under evidentialism and process reliabilism? Is the belief justified according to one epistemological framework of justification but unjustified according to the other? Is abiogenesis simultaneously justified according to both frameworks?

  • 7
    I suspect this question will lean too far into what the actual evidence is, which would be a question of science, not philosophy. The philosophy question might be whether some hypothetical scientific theory or hypothesis, supported by some abstract set of evidence, would meet the criteria for these frameworks. But I don't really know how one would ask that abstractly. Otherwise one might ask more broadly how one would go about evaluating claims under those frameworks, but the answer might just be "with evidence" and "via reliability", respectively.
    – NotThatGuy
    Commented May 26 at 19:29
  • 4
    Science split off from philosophy and might technically fall under it, but modern-day philosophy operates outside and around science. A philosopher wouldn't be the best person to ask about microbiology or whatever (unless they also happen to be a biologist).
    – NotThatGuy
    Commented May 26 at 20:33
  • 5
    Abiogenesis is justified evidentially, just not to the same degree as more established theories, like evolution by natural selection. Biologists synthesized requisite organic molecules in conditions similar to primordial oceans, and there are plausible models (RNA world) of how those could combine into proto-organisms. Stronger evidence would be experimental production of such proto-organisms in a lab, but that is currently beyond reach for practical reasons. As the evidence is obtained by scientific methods, presumed reliable, abiogenesis is also justified under reliabilism.
    – Conifold
    Commented May 27 at 4:40
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    You'd better define what "abiogenesis" means. From my own knowledge and a couple of dictionary definitions I just looked up, it means whatever process turned nonlife into life. There is ample evidence that life hasn't existed forever (there were not even any atoms 13.8 billion years ago), so abiogenesis happened. Wikipedia (which you linked) unusually says abiogenesis has to be "natural", in which case this seems the same as the other question you linked, and of course it gets into the problem of what counts as "natural".
    – benrg
    Commented May 27 at 17:38
  • 3
    And what's a natural process? A thing that happened in nature? A thing that happened without a human-like agent? A thing that happened in a way well-modeled by already well-supported physical principles? A thing that happened mechanistically, without the involvement of an agent who supervenes upon the mechanism but does not fundamentally alter and is not itself determined by the mechanism? The answer to this question could easily change from "yes" to "no" to "category error, we're just comparing ontological commitments" depending on the definition.
    – g s
    Commented May 27 at 20:36

5 Answers 5


The wikipedia article cited in the question clearly states:

The prevailing scientific hypothesis is ...

Meaning currently, science makes only weak claims about this being the current hypothesis, as opposed to something considered a fact. The main current open issue is also explained:

The precursors to the development of a living cell like the LUCA are clear enough, [...]. The process after the LUCA, too, is readily understood: [...] The derivation of living things such as the LUCA from simple components, however, is far from understood.

So a strong belief that abiogenesis must have happened cannot be fully justified by reliabilism, since the source supporting abiogenesis itself does not make such a strong claim.

Therefore a belief in abiogenesis as a fact is not justified only based on immediate evidentialism and process reliabilism, but also on something like naturalism (roughly the idea that "everything that exists" can be explained using the vocabulary and/or methods of the natural sciences).

Though naturalism itself might be justifiable in reliabilism, as over the last 2000 years, betting on naturalism rather than gods as cause would have been a winning bet many many times.


Abiogenesis literally just means "life arising from non-life." The term does not inherently place any restrictions on how this process played out, how quickly it happened, or at what time it happened. Strictly speaking, even divine intervention or some other supernatural explanation would constitute an instance of abiogenesis. Scientists routinely ignore such supernatural concepts under the broader principle of methodological naturalism, but that is not what you asked about. (And, as I have explained previously, methodological naturalism is not a factual claim in the first place, so you can't meaningfully ask whether it is "true" anyway.)

Under any epistemology, it seems very hard to argue that life does not currently exist. Similarly, if we take as given certain basic facts about the universe's cosmology and history (particularly the existence of the big bang), it seems very difficult to argue that life could have existed in the environment of the very early universe (everything was a soup of very hot subatomic particles, and there was no organized matter as we would recognize it today). From those two facts alone, it logically follows that abiogenesis of some kind must have happened at some time. Your question therefore boils down to whether evidentialism and process reliabilism are compatible with our current understanding of the early universe.

The big bang is principally supported by various astronomical observations, especially the cosmic microwave background, as well as mathematical tools like the Lambda-CDM model of the universe. The close correspondence between the CMB observations on the one hand, and the mathematical theory on the other, provides strong evidence that the big bang theory is a correct explanation of the early universe, and so most versions of evidentialism would hold this to be enough for a person to believe the big bang happened, and therefore for abiogenesis to have happened.

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    What "close correspondence"? Are you talking about how the observed CMB seems impossible according to present models? (Without, at least, introducing completely ad hoc pretzel-twists into the same?) In any case, I think Mark is asking whether abiogenesis without "help" is a reasonable belief.
    – Matthew
    Commented May 27 at 20:22
  • 2
    @Matthew: No, I'm talking about the entirely more prosaic fact that the CMB looks strikingly like a redshifted black-body radiation curve, and the amount of redshift matches up really, really well with what has been modeled. As for "without help" - that falls under methodological naturalism. Science does not assert that the explanation must necessarily be natural. It merely asserts that investigating natural phenomena subjectively appears to be a better use of scientists' time. You can't tell people that they're wrong about something like that.
    – Kevin
    Commented May 27 at 22:35
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    Solid answer. It's not obvious, but the original question is fundamentally about the definition of "bio-" and "life", and this answer gets closest to pointing out how any definition of "life" has to contend with the universe starting out lifeless.
    – Corbin
    Commented May 28 at 2:36

It's not belief in abiogenesis.. because there is no detailed candidate explanation to "believe"...(YET).

Abiogenesis is the name we use to describe the event that we cannot yet describe in detail.

Should it be accepted as "it did occur"?

It makes sense to do so... without an exact explanation... because there are...

... absolutely zero credible alternatives that make more sense.

So... the placeholder exists... and we seek to explain it exactly.

That's the whole story on abiogenesis to date... a placeholder and a "continue to try to figure it out exactly" situation.

  • We're just trying to fill in all the places on the blackboard where it says, "then, a miracle occurs."
    – Scott Rowe
    Commented May 28 at 2:09
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    @ScottRowe: The problem with the "God of the gaps" argument is that, over time, God gets smaller and smaller as we learn more about how things work. This has caused it to attract scorn from atheists and theologians alike.
    – Kevin
    Commented May 28 at 2:48
  • @Kevin I was referring more to the idea of unknowns as 'placeholders'. It is far more honest to say, "I don't know", than to say you've had the answer in your hip pocket all along. Have you seen the comic? (maybe God is like Ant-Man, incredibly powerful because He is so small) (shhh!)
    – Scott Rowe
    Commented May 28 at 2:54
  • @Kevin: Another perspective is that gods with Jehovah's power level were disproved some 2500 years ago via basic syllogisms and we have borne witness to the longest period of bargaining in history.
    – Corbin
    Commented May 28 at 17:58
  • @Corbin I've never before thought of Despair as something I wanted to move people towards, but perhaps it is necessary to get to Acceptance?
    – Scott Rowe
    Commented May 29 at 2:22

The way you are asking is hard to answer because you are asking about "belief in abiogenesis". Abiogenesis is not a proposition, it is just a term.

Let's construct some propositions:

Thesis 1: Life on earth started by abiogenesis (i.e. not through influence of mystical spiritual entities, aliens etc.)

Evidentialism cannot answer this question. If life started by abiogenesis, our best theories predict that that was billions of years ago. It is nearly inconceivable that we will ever find actual evidence about anything (that is not of geological time scales itself, i.e. things like the formation of the earth's crust, large scale changes like the advent of oxygen at large scale and so on) that happened that long ago.

Also, the way life works, it is in the habit of consuming/recycling itself - so whatever were the precursors of life as we know it today has very likely been consumed by slightly more evolved life; which is a further reason that it is incredibly unlikely to find actual visible evidence.

Process reliabilism, if I understand it correctly, stands a bit of a better chance; it would solve this question by scientifically answering ever more questions about the diverse possibilities in which life or close-to-life molecular structures could spontaneously come to existence; together with a good dose of Occam's Razor. The thing that speaks "pro" the thesis is the immense, unfathomable scale of time and space we are talking about here. Even incredibly small probabilities become significant if you multiply them by the time scales (literally billions of years) and available space (the whole volume near the top of our oceans). So Process Reliabilism would argue that it is all very plausible and any alternative would be kicked out by Occam's Razor.

Thesis 2: Abiogenesis is possible at all

Evidentialism can easily get closer to answering this with each experiment done in a lab which creates predecessor molecules. The Wikipedia page you linked shows several approaches. If science continues like this, eventually some lucky lab might just make a random breakthrough.

Process Reliabilism's answer is basically the same as for any other scientific endeavour that's still in the stage of being worked on - it would look at whether all the work on it is happening to true scientific standards, and if we were convinced that there are no shady shenanigans going on, nothing much would stand in the way.

In both cases, the probability argument of the previous thesis speaks kind of against us - since the probability is obviously very low (or we would have found it already), and since the time/space volume on Earth was so very high, we cannot really judge thesis 1 from the results of thesis 2, unfortunately. I.e. even if we never find proof for thesis 2, this does not rule out thesis 1.

  • 1
    Even incredibly small probabilities become significant if you multiply them by the time scales (literally billions of years) and available space (the whole volume near the top of our oceans) - Speaking of probabilities, this paper might be relevant: philosophy.stackexchange.com/a/109968/66156
    – Mark
    Commented May 28 at 13:23
  • The probabilities mentioned are exponentially small, which means that multiplication by large constants does not make them non-small. You need a different explanation for how complexity arises. One happens to come from non-equilibrium thermodynamics: because we sit next to a hot star, our chemical species are constantly increasing in complexity. Origin-of-life research is aware of this; each abiogenetic experiment assumes that the precursor chemicals evolved through other reactions already, with the exception of Miller–Urey.
    – Corbin
    Commented May 28 at 17:54
  • Interesting molecules apparently form in open space, so forming them in a nice warm ocean seems quite likely.
    – Scott Rowe
    Commented May 29 at 2:25
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    Since we're in Philosophy.SE here and not in Chemistry.SE or Biology.SE, my point is that exactly discussions like this ("it is very unlikely" - "but there is so much time and space" - "but the one is exponentional, the other polinomal" - "but entropy from the sun helps" - etc etc.) is exactly what makes Process Reliabilism "work" to build beliefe in this. Obviously with a bayesian mindset (i.e. we don't know until we know, but we can put a probability on it, and P.R. helps us to judge where on the scale of likelihood we might be).
    – AnoE
    Commented May 29 at 8:30

My two cents opinion:

The matter of "abiogenesis" depends heavily on what we consider "life" or "living" to be (*). This is the main point.

In other words, genesis or transformation of this to that, has been observed has been proposed (**), but is it interpretable as a-bio-genesis, or rather as bio-transformation from one form of living to another (similarly to how energy is not created nor lost but only transformed)?

One can be equally well justified, from the same observations, to take the stance of bio-transformation instead of a-bio-genesis, simply extending the definition of "bio".

The definition of life has long been a challenge for scientists and philosophers. This is partially because life is a process, not a substance. This is complicated by a lack of knowledge of the characteristics of living entities, if any, that may have developed outside Earth. Philosophical definitions of life have also been put forward, with similar difficulties on how to distinguish living things from the non-living.

Life, Wikipedia (*)

The transition from non-life to life has never been observed experimentally, but many proposals have been made for different stages of the process.

Abiogenesis, Wikipedia (**)

  • Yes, we could solve the problem by saying that everything is alive. People have tried that. So then the question becomes, how did everything gain life? Through a natural or supernatural process?
    – Scott Rowe
    Commented May 29 at 14:40
  • @ScottRowe we had this discussion in the "Big Bang" post, remember?
    – Nikos M.
    Commented May 29 at 14:56
  • Well, it is comforting to know that we can define problems away by changing definitions. Unfortunately, we can also define problems in to existence that way. We have to be careful with words. We could redefine 'supernatural' to something innocuous and everyone could then agree.
    – Scott Rowe
    Commented May 29 at 16:20
  • @ScottRowe if the problem is in how to define something it means : either a) we don't yet know the correct definition else b) we have freedom in defining something as this or that. In both cases we don't have an absolute truth to claim.
    – Nikos M.
    Commented May 29 at 16:49
  • @ScottRowe still another option c) is when the various definitions are not that different eventually but related from different relative perspectives. Then it can be said that, in a sense, state the same thing.
    – Nikos M.
    Commented Jun 1 at 18:44

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