Why I Can’t Be An Atheist

Almost a year ago I started posting about my exploration of what I see as the strongest arguments for and against the existence of God, and I started writing these posts several months earlier than that. Almost half of the posts on my blog so far have been directed at this question. (And on top of that, apparently my average word count per post has been higher this year than last!) So it has been a fairly long project.

Looking back over all of the thoughts I’ve gathered, here is where I find myself: I cannot be an atheist.

I can imagine why someone might be an atheist. I can imagine how you might weigh the considerations differently so that atheism is reasonable, even. But for me, that is not an option. For me, the arguments for God’s existence substantially outweigh those against.

What I Have to Believe to be an Atheist

Here is what I would have to believe in order to be an atheist:

  • The principle of sufficient reason is false, and the fact that the universe seems to work like it is true is just one huge coincidence. Abductive and inductive reasoning is invalid, and most of our scientific reasoning is undermined.
  • There is ultimately no reason why the universe (or anything at all) exists, or is the way that it is.
  • There is no explanation for the finely-tuned structure of the physical universe, except perhaps for vastly improbable chance.
  • The existence of consciousness is inexplicable, and in fact, because of this, the connection between our experiences and any external reality becomes dubious.
  • There is no such thing as objective morality, no right or wrong. Morals are just subjective impressions foisted upon us by our evolutionary and cultural history, and we have no fundamental obligation to follow them.
  • There is no such thing as objective beauty. Any sense of the transcendent we have in the sight of something beautiful; any experience of awe and wonder at the world around us; is empty and illusory.
  • There is even no such thing as objective rationality, and it is dubious whether our ways of reasoning, even deductively, are capable of reliably producing truth.
  • In a universe void of the transcendentals of truth, goodness, and beauty, with no teleology in our creation, living insignificant lives in the overall scheme of things, and universally destined for non-existence no matter what we do, life is ultimately without value, purpose, or meaning. (And we can pretend otherwise, but it doesn’t change the reality.)

In contrast, in exchange for the meaningfulness, explanatory coherence, and firm foundation that theism brings to one’s worldview, I only have to accept these tensions in order to be a theist:

  • I cannot fully understand why God would create a world containing evil and imperfection (though I can come up with some plausible reasons why he might do so, in general).
  • I cannot fully understand why God would not make more complete revelation of himself universally available, instead revealing himself in particular places and times in history and allowing many false religions and ideas about him to propagate (though again, I can come up with some plausible reasons why he might do so, in general).
  • I cannot fully understand how God has acted in regards to salvation, eternal life, and those who are excluded from that destiny (but logically, I see no barrier to things turning out in a way that accords with his goodness).

I could, perhaps, be accused of playing things up a little bit here for rhetorical effect. I am not saying that these conclusions are obvious and rationally compelling for everyone. I don’t think all atheists are inherently irrational. But at the end of the day, I do think they are mistaken. Under the light of the arguments for God’s existence, I find that atheism results in absurdity.

I admit haven’t spent as much time exploring and responding to the arguments against God’s existence on this blog as I would have liked to – there is much more that could be said (and has been said, elsewhere on the internet) regarding those subjects. And ideally, in a wrap-up post like this I would be including a quantitative assessment of the cumulative strengths of the reasons for and against belief in God, accounting for the degree of dependence or independence between the different arguments.

I will at least attempt to do that quantitative assessment, briefly, here. (“Briefly.” Ha.)

Quantifying Belief

In the comments on a post a few weeks back, one gentleman (who his own blog worthy of reading) suggested a high-level categorization of the arguments for and against God’s existence, and I think it is a good way of looking at things:

  • Argument from Reality: theism is the best way to explain some fundamental features of reality (encompassing the cosmological, teleological, noetic, and axiological arguments).
  • Argument from Imperfection: atheism better explains the fact that reality is full of imperfection (encompassing the problem of non-god objects, the problem of evil, and dysteleological arguments).
  • Argument from Revelation: theism is supported by experiences of God and the evidence of God’s actions in history (encompassing the epistemological and historical arguments).
  • Argument from Indifference: atheism better explains the apparent indifference of religious revelation (encompassing the problem of divine hiddenness, the problems of religious pluralism and religious disagreement, and the problem of exclusivity).

The argument from imperfection is paired against the argument from reality, and the argument from indifference is paired against the argument from revelation. (One further category, which I’m not going to consider in this analysis due to the difficulty of casting them as abductive arguments, would have the ontological argument on the side of theism, and contradictions in the concept of God on the side of atheism.)

Now what I want to do is run a Bayesian analysis of the odds for theism over atheism, considering each of these arguments in turn: reality (R1), imperfection (I1), revelation (R2), and indifference (I2). Using the odds-ratio form of Bayes’ theorem, and iterative use of the fact that P(A & B) = P(A|B)*P(B):

\frac{P(G|R1,I1,R2,I2)}{P(\sim G|R1,I1,R2,I2)}=\frac{P(I2|G,R1,I1,R2)}{P(I2|\sim G,R1,I1,R2)} \times \frac{P(R2|G,R1,I1)}{P(R2|\sim G,R1,I1)} \times \frac{P(I1|G,R1)}{P(I1|\sim G,R1)} \times \frac{P(R1|G)}{P(R1|\sim G)} \times \frac{P(G)}{P(\sim G)}

To make estimating these probabilities a more reasonable task, I am considering them all to be conditional on some level of background knowledge which frees us from having to consider the probabilities of many irrelevant specific contingent data about the world. In this way the focus can be on whether each worldview in consideration (theism or atheism) has the resources to explain the high-level facts we are interested in.

Even with that, it is hard to pin down some of these numbers, so I will actually model them as a distribution of probabilities. More on that below.


First, I think it is fair to consider the prior odds of theism (and atheism) to be one to one, or approximately so. I mentioned Paul Draper’s “low priors” argument a few posts ago, but as I said then, I don’t think it is successful. The intrinsically symmetric alternatives that he considers, “source physicalism” and “source idealism,” both need to be further specified to account for the full range of data. And I see no reason to think that theism must be further specified from source idealism than a viable form of atheism must be from source physicalism.

So P(G)/P(~G) = 1.


Now, does the existence of God provide a solid ground for the fundamental features of reality (e.g. existence, appearance of design, consciousness, objective value) that need to be explained? Without considering any of the imperfections in reality – that is the next argument, not this one – I would say the answer is a solid yes. So I will set P(R1|G) = 1.


The argument from reality is atheism’s weak point, in my mind. In order to explain these fundamental features of reality, it faces all the difficulties that I raised above. (And I’m trying to stick to the rational difficulties, but there are serious existential difficulties as well.) My initial impulse is to rate this probability no higher than 0.01, with 0.001 being closer to what I would put it at on most days. Just the failure of the PSR alone, I think, is worth putting it below 0.01.

That is probably a bit extreme, so I will ease off by a factor of 2 and say P(R1|~G) = 0.002 to 0.02. (Median value 0.006.)


Of the considerations that could go under the argument from imperfection, I have only specifically addressed the problem of evil on this blog. But the others, the problem of non-god objects (why would God, a perfect being, create anything at all?) and dysteleological arguments (why would God create things that appear poorly designed?) do not add much weight to it, honestly. And given what I think are good responses to the problem of evil, I don’t think this probability needs to be much lower than 0.5.

But recognizing that the argument from imperfection does cause some tension for theism, I will estimate P(I1|G) = 0.1 to 0.4. (Median value 0.21.)


Assuming atheism could overcome the argument from reality, can it explain all the imperfections and evils that we see? Yes, completely. P(I1|~G) = 1.


The question here is whether it makes sense for God to provide some revelation of himself and whether theism can account for the kind of examples of revelation that we see. I think the answer is yes, in general, and that this probability is pretty close to 1. To make things simpler, any doubt about this can be transferred to a boost to the next probability. So P(R2|G) = 1.


For me, this probability would be pretty close to 1 (making the argument from revelation quite weak) if it were not for the events surrounding Jesus’ death and the origin of Christianity. I do think atheism has difficulty explaining the evidence that we have for what happened there.

Nevertheless, assessing the argument for the resurrection is a complicated matter, and I am fairly uncertain about just how much force it has. My initial thought is to put this probability anywhere from 0.01 to 0.5. To offset the value of 1 given to the corresponding probability on theism, I will set P(R2|~G) = 0.05 to 0.6. (Median value 0.22.)

(*Note: in an earlier version of this post, I instead set P(R2|~G) at 0.15 to 0.75, wanting to be generous to the other side. But upon later reflection, I felt this really underrepresented my assessment of the strength of the evidence, even taking my uncertainty about that into account. With the original numbers, the median value for my overall probability for God’s existence was about 91.5% instead of 95.3%.)


The question that theism has to face now is why God’s revelation of himself is apparently so ineffective and localized. Why would God not make his existence more obvious? Why is there so much religious confusion? How could God leave people in this state of uncertainty, and then condemn them to hell?

The kinds of considerations that I have raised in response to these things in that past few posts go a ways to reducing the tension that the argument from indifference brings to theism – but I find it more difficult to overcome than the argument from imperfection. Let us say that P(I2|G) = 0.05 to 0.3. (Median value 0.13.)


Finally, can atheism explain the apparent indifference of religious revelation? Again, it can do so perfectly. P(I2|~G) = 1.

For each of the four probabilities with a range of values, I have modelled them using a logit-normal distribution with the upper and lower values listed above set to the 10th and 90th percentiles. These are what the distributions look like:


subjective distributions

And once these random values are put into the Bayesian equation, and the result converted into a distribution for the posterior probability that God exists (using 10,000 sets of randomly generated numbers to estimate the distribution), this is what I end up with:

subjective distribution output smoothed

This ranges from 82% at the 10th percentile to 98.8% at the 90th percentile, with a median probability of 95.3%. (An equal probability for theism and atheism, at 50%, is down below the 1st percentile in this distribution.)

So, there you have it. Given how I’ve weighted the above arguments, I should on average be a bit more than 95% confident that God exists.

Faith and Reason

This value (or distribution of values) represents an assessment of the strength of the rational justification for belief in God. Obviously, it is a product of several subjective judgements, and different people could weight the arguments differently and get a different number out as a result. On a different day, I myself might feel that different numbers are more appropriate than the ones I have given here. So this number shouldn’t really be thought of as any kind of precise determination of my level of belief in God.

But even more than that, while rationality is extremely important, at the end of the day I have to admit that it isn’t the only consideration that goes into forming one’s beliefs. There are existential considerations as well: considerations about finding meaning and purpose in our lives, and about how our beliefs are going to impact the way we live. So while I definitely think that there are good reasons to believe in God – 95% isn’t insignificant, after all – there is more than that. And the meaning and purpose of life that I find in the theistic worldview draws me, essentially, to commit to what I see as the truth.

The existence of God is too important, and the implications too far-reaching, for it to be practical to be indefinitely weighting the reasons for and against theism, holding that left tail of the distribution in mind and wondering if it will change. This gets back to something I wrote about at the very beginning of my blog: we need critical thinking, but we also need epistemic faith. When we see good reasons to accept a belief – as I see good reasons to believe in God – we should trust that, and not linger in unnecessary skepticism.

Basically, what I am saying is that I am willing to take that last 5% on faith, and I think it is proper to do so. I will trust what I have good reason to believe.

This does not mean that I think I should seal up the issue of belief in God and never subject it to scrutiny again. If something comes up that makes me think about how I’ve weighed the evidence, or if I come across some new consideration that could affect the balance, I am willing to take a look at it. (Granted, given the scope of my exploration of this issue so far, I admit that I find it unlikely that something will ever impact my belief so much as to make me change my mind. But I want those who disagree with me to be open to changing their mind, so I should probably exhibit the same attitude!)

So, that is why I am not an atheist. In my next post, I will write a little bit more on why I believe that Christianity, specifically, is true.

Science, Philosophy, and Religion

What do you think of when you think about how we, as a society, learn and acquire new knowledge? It seems like the dominant mindset in our culture finds the pursuit of knowledge to be closely associated with the activity of science. Science is upheld by many as the epitome of rationality, or even as the only valid way of justifying our beliefs and gaining knowledge.

In contrast, the field of philosophy is now widely held to be useless, having been eclipsed by science as a means of finding out the truth. This attitude is expressed by none other than physicist Stephen Hawking in his book, The Grand Design (co-authored with Leonard Mlodinow):

“Traditionally these are questions for philosophy, but philosophy is dead. … Scientists have become the bearers of the torch of discovery in our quest for knowledge.” – Stephen Hawking and Leonard Mlodinow

And close on the heels of these kind of statements, there is the popular belief today that religion is the exact opposite of science, the epitome of anti-rationality. Religious faith is thought of as being, by definition, belief without evidence, or even belief in spite of the evidence. Religion and science are believed to be incompatible at a fundamental level.

These ideas – that science is the only source of knowledge or that it has eclipsed all others, that science and religion are incompatible, and that religious faith is opposed to reason – are, to put it bluntly, completely wrong.

Science and Knowledge

“You are right in speaking about the moral foundations of science, but you cannot turn round and speak about the scientific foundations of morality.” – Albert Einstein

It seems to me that the most appropriate way to define science is as the rational and empirical study of nature (including humans and their activity within nature). This definition encompasses the physical sciences, such as physics, chemistry, biology, geosciences, and astronomy; as well as the social sciences, such as history, economics, political sciences, psychology, and sociology.

Note that this definition does not include the formal sciences, logic and mathematics, as these lack the empirical methodology that characterizes science proper. Nor does it include the practice of the applied sciences, such as engineering and medicine, as they are aimed at applying knowledge rather than discovering it. (However, research activities in the applied sciences do properly fall under science as I have defined it here. Which is why you can get a M.Sc. in engineering.)

What all of the disciplines within science proper have in common is the scientific method. This is not really a single method, but a group of interrelated methodologies, including observation, hypothesis, prediction, confirmation or disconfirmation of theory through evidence and experiment, and peer-review to eliminate error and bias as much as possible. Scientific theories are prototypically falsifiable and open to discussion and criticism.

And science works. It has shown itself to be incredibly successful at discovering the workings of the natural world. It works well precisely because it embodies the virtue of critical thinking, by demanding justification for its beliefs in the form of evidence. But the fact that science is successful does not imply that it is the only way to acquire knowledge about reality, or even that we should hold it up as a model that all other ways of acquiring knowledge ought to resemble.

The simple reason for this is that science rests on philosophical foundations that cannot be justified by science itself. Let’s say you want to use science to study the electromagnetic interaction between electrons and protons. Before you can do that, you need:

  • epistemological beliefs about what is rational and what is not;
  • further epistemological beliefs about the validity of deductive, inductive, and abductive reasoning;
  • metaphysical beliefs about the existence of the physical world and its relation to our perceptions of it;
  • further metaphysical beliefs about the uniformity and predictability of the physical world, for example, that electrons and protons in the same conditions will always behave in the same way;
  • even further metaphysical beliefs about the nature of causation, if you want to move from merely describing what happens to electrons and protons (the particles moved in a certain way) to explaining why it happens (because the electromagnetic field exerted a force on them);
  • ethical beliefs about the right way to conduct science, for example, that you must report your research truthfully and that you must not plagiarise.

The scientific method presupposes all sorts of philosophical beliefs like these, and none of them can be justified by the scientific method alone. But if these beliefs that underlie science are not justified, then science itself cannot justify any other beliefs.

Scientism, which is the belief that science is the only valid source of knowledge, is itself a philosophical belief rather than a scientific one. And scientism is self-defeating. If it were true, the philosophical presuppositions of science, and therefore science itself, would be unjustified. So science would not be a valid source of knowledge after all – if scientism is true, then it is false. It’s unfortunate that even incredibly intelligent scientists like Hawking can apparently fail to recognize this.

So, science is not and cannot be the only source of knowledge. Good thing, too – so far in this blog, all I have been doing is philosophy, and it would be a shame if all of that effort had gone to waste. Now, I don’t want to give the impression that philosophy is the foundation of all knowledge, either. Really, what I have argued is that the foundation of our knowledge is common sense.

(That being said, philosophy is an invaluable resource in clarifying the foundations of knowledge and the implications and interrelations of knowledge from all sources. You can’t really avoid doing it if you undertake to build a coherent and comprehensive belief system, as I am doing.)

Science and Religion

“There is superficial conflict but deep concord between science and theistic religion; and superficial concord but deep conflict between science and naturalism.” – Alvin Plantinga

To give an overly simple definition, religion is a set of beliefs about the supernatural (and more broadly, about all of reality as it relates to the supernatural). Religious faith is trust or confidence in those beliefs. If science is a way of getting knowledge from the natural realm, religion could be considered a way of getting knowledge from the supernatural realm. This kind of knowledge comes about in much the same way as other knowledge: people have religious experiences and intuitions, they draw conclusions about the supernatural from other beliefs through reason, and they pass on their beliefs to others through testimony.

If religion refers to a set of beliefs, or even if it refers to the practices and rituals associated with those beliefs, it should be evident that religious faith is not necessarily opposed to reason, or to science. The concept of faith that seems to be widely held outside of religious circles (and unfortunately, by some within them) is that it is irrational belief without justification, even going so far as celebrating ignorance as a virtue. But this is a caricature of the concept of faith as it is understood by many believers of different religions.

I am most familiar with the Judeo-Christian tradition, so that is where I will speak from. The kind of faith in God that is commended in the Bible is not irrational confidence in belief without evidence. Rather, it is confidence in one’s beliefs specifically because of the evidence that supports them. In the Old Testament, the nation of Israel is commanded to remember how God brought them out of Egypt, as evidence of his power and faithfulness. In the New Testament, the writers of the Gospels say they wrote what they did specifically to give evidence for belief, through testimony. And the apostle Peter writes that Christians should be ready to give reasons for their faith.

So the biblical concept of religious faith is complementary to critical thinking, not opposed to it. Which is one of the reasons I think that, if they are understood properly, science and religion are united by a common purpose: to conform your beliefs to the truth. Science is about doing this for truth we can discover in the natural world, religion for truth we can discover in the supernatural. Of course, there can be overlap between these two pursuits, for example, if you believe that God created the world and has revealed some things to us about it. But because truth cannot contradict truth, true science and true religion cannot contradict each other.

Of course, religion can find truth in the supernatural realm only if the supernatural exists. Whether or not it does is a question for a later time. But for now, I just want to recognize that there will be a conflict between science and religion only to the extent that science is seen to be inextricably linked to metaphysical naturalism, the belief that there is nothing supernatural in reality.

But I don’t think you can show that doing science requires you to accept naturalism: many scientists are also adherents to one religion or another, without feeling that science compels them to abandon religion, or vice versa. And naturalism, as a fundamentally philosophical belief, is not one that science can justify: merely studying nature cannot prove that nothing outside of nature exists.

Nothing about studying the natural world requires that we deny the existence of the supernatural. Certainly, beliefs about the supernatural can affect how we do science. If you have a pagan conception of the universe that deifies the forces of nature and hosts a pantheon of capricious, conflicting gods, who were ultimately born from a primeval chaos – well, then, science might be a non-starter, since everything is effectively supernatural. Conversely, though, a belief in a rational and transcendent God, separate from the universe He created, can produce or strengthen a scientific belief in the order and predictability of nature.

Arguably, it has done just that, for at least one scientist:

“The chief aim of all investigations of the external world should be to discover the rational order and harmony which has been imposed on it by God and which He revealed to us in the language of mathematics.” – Johannes Kepler

So I think we can move on from the ideas that science and religious faith are fundamentally opposed to each other, or that science is the only fount of knowledge that we can drink from. Instead, let’s search for truth, with critical thinking and epistemic faith, wherever it is to be found.


A little post-script: there are a lot of authors who have explored, much better than I have, the idea that science and religion are not really in conflict the way that they are often proclaimed to be. Here are some good books to read about this, if you’re interested:

  • Galileo Goes to Jail and Other Myths about Science and Religion, by Ronald Numbers
  • God’s Undertaker, by John Lennox
  • Where the Conflict Really Lies, by Alvin Plantinga

How to Seek Knowledge

If the different ways that we justify our beliefs are the building materials for a structure of beliefs, then perhaps I can call the process by which we evaluate and adjust our beliefs the scaffolding for that structure. That is the topic of this post.

First, though, I want to make a couple of observations about the principle of critical trust that I presented in the last couple of posts. The essence of this principle is found in the two intellectual virtues that I explored earlier, critical thinking and epistemic faith. In using this principle, we extend initial trust to the beliefs that we naturally form from conscious experience, intuition, and testimony. Then we sift through those beliefs to try and discard the ones that are false, and strengthen the ones that are true.

The first observation I want to make here is that the principle of critical trust is not an “anything goes” principle. It does not mean we can believe whatever we want. Rather, it means we start by believing that things are the way they seem to be, on the basis of our conscious experience, intuition, and testimony – these initial beliefs must still have some kind of justification – and then we use reasoning to try and figure out the way things actually are.

The second observation is that, although the justification for these initial beliefs is not free, it is not all that costly either. We can usually find justification for what we want to believe, if we look for it. That is why it is important to weigh the justification both for and against a belief, rather than just looking at one side.

As a third observation, a corollary of the principle of critical trust is that when a belief is defeated by reasons to disbelieve it, it is rational to retain as much of the content of the belief as possible. For example, if you think you recognize your friend John on the street, but then later find out he was not in the city, you wouldn’t immediately think you had hallucinated the whole experience. You would think you had just seen someone who looked like John.

Worldview Formation

When I talk about constructing a belief system, what I principally have in mind is the formulation of a worldview, a comprehensive theory or perspective for categorizing, explaining, and interpreting all of reality. A belief system is essentially a worldview and the outworking of that worldview in the way that it interprets the world.

Everyone has a worldview, whether consciously or not – we all go through the process of creating an explanation and interpretation of everything we experience. We don’t have the capacity to deal with all of the diverse truths about reality independently. A worldview allows us to deal with all these truths in a unified way.

So, the principle of critical trust, and the need for a worldview, together suggest the following approach for forming, evaluating, and adjusting our whole belief system.

  • Presumptive Data: as presumptive data, accept that things are the way they seem to be, based on the sum of one’s conscious experiences and intuitions, and the testimony received from others. All of these data have a small amount of initial justification.
  • Initial Sifting: some of the presumptive data are likely to conflict with others. Sort the data into maximal consistent subsets (sets that contain as many beliefs as they can without containing a contradiction), and believe the subset with the most initial justification (rejecting the beliefs that conflict with this subset).
  • Worldview Formation: based on the beliefs accepted from sifting, form a worldview that explains as many of one’s beliefs as possible (principally, using inference to the best explanation).
  • Feedback Sifting: based on one’s worldview, some of the initially accepted beliefs may be rejected, and some of the initially rejected beliefs may be accepted. New presumptive data may be brought into consideration from re-interpretation of one’s experiences, intuitions, and received testimony in light of the new worldview. These two principles are important here:
    • Principle of Epistemic Defeat: reject beliefs that are in conflict with the best explanation of a vast number of other accepted beliefs. When beliefs are defeated in this way, retain as much of their content as possible that is undefeated.
    • Principle of Epistemic Enhancement: when an accepted belief is coherent with or suggested by the best explanation of a vast number of other accepted beliefs, its justification is enhanced.
  • Re-evaluation: New data or new understanding of old data may challenge one’s worldview, eventually forcing a re-evaluation and re-formation of the worldview when the data that cannot be fit into it acquires enough weight.

By going through this process, forming and re-evaluating our worldview and the whole system of beliefs associated with it, we will (hopefully) come to believe more and more truths, and disbelieve more and more falsehoods, in a validly justified way. That is, we will come to acquire more and more knowledge.

But the key to this process being successful in the long run is having the right worldview. If your foundational beliefs are true, you are more likely to interpret the data correctly, leading to further knowledge. If your foundational beliefs are false, your interpretation of the data is more likely to be wrong, impeding the search for knowledge.

Pilate’s Question

So I think I have adequately covered the nature of knowledge, and when it is reasonable to hold a belief. Now I come to a question that has been hovering in the background for a while. Belief is an attitude of accepting a proposition as true. Knowledge is validly justified true belief. I have claimed that it is important to hold a true worldview. And all throughout, I have been upholding the value of rationality – but the value of rationality is just that it allows us to know what is true.

But what is truth?

That is the topic I will turn to in my next post.

Building Materials (I): Deductive Reasoning

I’ve been surveying the ground on which to build a comprehensive belief system. Here are the main conclusions that I have come to so far:

  • A belief is an attitude of accepting a proposition as true.
  • Knowledge, the kind of belief that we want to hold, is validly justified true belief.
  • Justification for a belief is valid if it is appropriately connected to the truth of the belief.
  • Some beliefs are justified by other beliefs, and some beliefs are properly basic, that is, justified without reference to other beliefs.
  • Some of our properly basic beliefs are things we just know intuitively; among these are beliefs about what counts as knowledge and what doesn’t.

Now I am going to take a look at the “materials” out of which a belief system can be built: the ways that we actually use to justify our beliefs, in practice. I think the different forms of rational justification can be grouped into five categories:

  • Deductive reasoning
  • Abductive or inductive reasoning
  • Experience
  • Intuition
  • Testimony

In other words, there are five different ways to answer the question, “How do I know that?”

  • “It follows logically from these other things I know”
  • “It is the best explanation of these other things I know”
  • “I directly observe it in my conscious experience”
  • “I just intuitively see that it is true”
  • “Someone told me so”

The different forms of reasoning justify beliefs using other beliefs, while experience and intuition are ways of forming properly basic beliefs. Testimony can also be treated as a source of properly basic beliefs.

I am focusing here on rational justification, but I think in some cases there can be pragmatic justification for a belief. That is, sometimes you can be warranted in holding a belief, even when you do not have sufficient rational justification for it, because of the useful consequences of holding that belief. In fact, I think there are probably situations where you can’t actually find rational justification for a belief until after you have accepted that belief on pragmatic grounds. (You could argue that my project here of trying to discover the nature of knowledge and justification is such a situation.) But for now I want to try to keep pragmatic and rational justification distinct, and build my belief system using rational justification where I can. (And I also think that it is only rational justification, not pragmatic justification, that confers knowledge.)

Alright. With that preamble, the first “building material” that I will look at is deduction.

Deductive Reasoning

Deductive reasoning is the use of logic to derive a conclusion from one or more premises. Here is an example of a deductive argument:

  • Premise: If it is raining, then the ground is wet outside.
  • Premise: It is raining.
  • Conclusion: Therefore, the ground is wet outside.

Deductive arguments derive conclusions from premises using certain logical rules, called rules of deduction. If those rules are followed correctly, and the premises of the argument are true, then the conclusion of the argument is true. (Deductive reasoning can also be used where the premises are not certain, but where they are thought to have some probability of all being true: then a valid deductive argument guarantees the conclusion is at least that likely to be true.)

The above argument correctly uses the rule of conditional elimination (often called by its classical name, modus ponens) to derive its conclusion from its two premises. So, if those two premises are true, then the conclusion is guaranteed to be true. But the conclusion could still fail to be true if either of the premises is false. (For example, maybe it isn’t raining, or maybe rain doesn’t make the ground wet because the ground happens to be made of a super-absorbent material.)

Deductive arguments can also fail if they do not correctly follow the rules of deduction. For example:

  • Premise: If it is raining, then the ground is wet outside.
  • Premise: The ground is wet outside.
  • Conclusion: Therefore, it is raining.

This argument is invalid, because the truth of the conclusion is not guaranteed by the truth of the premises. (There could be another reason that the ground is wet; for example, maybe it isn’t raining but someone decided to dump buckets of water on the ground.) An incorrect use of the rules of deduction is called a formal fallacy. This example commits the fallacy called affirming the consequent.

Logical arguments can also suffer from informal fallacies. These have to do with the content of the argument, rather than its structure. For example:

  • Premise: Either pigs can fly, or the Earth is approximately a sphere.
  • Premise: Pigs cannot fly.
  • Conclusion: Therefore, the Earth is approximately a sphere.

This argument is logically valid and its premises are true. But the only reason you have for believing the first premise is that you already believe the conclusion; so this argument tries to support the conclusion using the conclusion itself. This is an informal fallacy often called begging the question.

So, if a deductive argument is free from any fallacies, and you justifiably believe the premises (or at least think it is likely that they are all true), then the argument provides good justification for its conclusion. Because the truth of the conclusion rests on the truth of the premises, for such justification to be valid, the premises should be true and themselves validly justified.

That is the first form of justification. In my next post, I will look at other forms of reasoning that we can use to justify our beliefs.

Belief and Meaning

With this post I am commencing an ambitious construction project. I am attempting to build an entire belief system from the ground up, making sure that each of the beliefs I hold is supported by a firm foundation. And as with any structure, the first thing that needs to be built is the foundation itself.

I think an obvious place to start building a belief system is simply to ask: what is a belief?

In this context, I am not talking about belief in something or someone, which is roughly synonymous with trust. Rather, I am talking about belief that. I believe that the Earth is approximately a sphere, for instance. This sentence expresses the fact that I have a certain attitude towards the proposition that the Earth is approximately a sphere. Specifically, an attitude of accepting this proposition as true.


Here I think it is useful to introduce a concept for describing the content of beliefs, truth, and knowledge. We can express beliefs and the like with assertions, which are spoken or written sentences which assert some state of affairs. “The Earth is approximately a sphere” is an assertion. So is “Die Erde ist ungefähr eine Sphäre.” Of course, these assertions mean the same thing (at least according to Google Translate), and if I believe one, then I believe the other. The content of the belief is not the specific expression, but the intended meaning behind it.

Philosophers use the term proposition to refer to the meaning of an assertion, abstracted away from its expression. Often, propositions are represented as subordinate clauses headed by that: such as the proposition that the Earth is a sphere. This is just to make it clear that we care about the meaning behind the assertion, and not the assertion itself.

One of the reasons we make this distinction is that assertions, taken literally, are just sound waves in the air or ink marks on a page. Sound waves or ink marks by themselves cannot be true or false. For it to make sense to talk about the truth or falsehood of an assertion, or the reasonableness of believing an assertion, it has to have an understood meaning. Propositions represent this meaning.

The other reason we make this distinction is that human language is often redundant, imprecise, or ambiguous. More than one assertion can refer to the same proposition, most obviously between different languages, but this is the case even within the same language. Even more problematically, more than one proposition may be the intended meaning behind some assertion. “The missing painting was found by the art gallery” has more than one possible meaning, for example. (It could mean that someone found the painting near the art gallery, or that the art gallery found the painting.) Since the meaning is what we care about, we use the concept of propositions.


A belief, then, is an attitude towards a proposition that accepts that proposition as true. In other words, it is a mental state of accepting as true the meaning behind some assertion. So, believing something is roughly the same as thinking that it is true.

Of course, understanding that definition of belief requires that we understand the meaning of truth. I am going to go into more detail about that, but not just yet. For now, I will give the common-sense notion that when we say something is true, we mean it is the way things are. (Even when I go into more detail, the common-sense notion pretty much sums it up.)

Belief comes in degrees. We can have different measures of certainty or doubt about the truth of any given proposition, though these measures are subjective, and typically more qualitative than quantitative. You can be certain about a belief, or uncertain but think it is more likely true than false, while still believing it. The degree of certainty that you need for a belief isn’t something that can be precisely defined, and it may vary depending on the gravity of the belief in question. In some cases you can be entirely uncertain about a proposition, but still accept that proposition as true for pragmatic reasons.

These degrees can go in the direction of doubt instead of certainty. Disbelieving a proposition is just believing that it is false, and disbelief can also range between entirely certain and entirely uncertain. Finally, you can suspend belief in a proposition, meaning that you neither believe nor disbelieve it. This may be because you are evaluating the evidence for it, or just because it is not a matter of concern.

What kind of beliefs do we want to hold? And why do we care about the level of certainty we have in our beliefs? Well, since belief is accepting a proposition as true, we want to have beliefs that are, in fact, true. We want our beliefs to line up with the way things really are. That is where reasons come in. If I had started this whole discourse by saying that I wanted to explore merely my beliefs, I doubt it would have sounded as interesting to you. (Maybe it didn’t sound interesting anyways, in which case, why have you read this far?)

We intuitively understand that just having a belief is not enough. We want reasons to think that what we believe is true. Moreover, we want those reasons to be good ones, reasons that justify us in holding those beliefs. Part of critical thinking is aligning the level of certainty that we have in our beliefs with the level of justification that we have for them.

This concept of the kind of belief we want to hold is important enough that we usually give it its own word: knowledge. We want to do more than believe. We want to know.

So my exploration of what I believe, and why, is really an exploration of what I know, and how I know it. Which is why, over the next few posts, I am going to spend several thousand more words going a bit more in depth on what knowledge is and how we get it.

Beliefs and Reasons

“A reasonable person believes, in short, that each of his beliefs is true and that some of them are false.” – W. O. V. Quine

I have been thinking about writing this blog for the past few years. I spend most of my free time these days thinking, and reading, and writing; I thought I should eventually share what I have been doing all this thinking about. So what have I been thinking about? In as few words as possible: everything I believe.

I’ve become burdened with a desire to clearly articulate the beliefs that I hold, and the reasons that I have for holding them. In the process, I’m trying to make sure that I have good reasons for what I believe. It’s my hope that you will find it interesting to learn what I believe, and why, whether or not you hold the same beliefs. And whether or not my reasons convince anyone that I am right, I hope that by sharing my thoughts, I can encourage others to engage in a similar exercise. What we believe is important, because it affects the way that we live. So thinking critically about our beliefs is an important aspect of life.

The quote above is a nice summary, to me, of what critical thinking entails. It means having thought carefully enough about each of our beliefs so as to be convinced of their truth, but also recognizing our own limitations so as to realize that we are probably wrong about some things. This requires knowing not just what to think, but how. And in the era of “post-truth politics,” it seems like the skill of critical thinking is becoming less common. Echo chambers abound, and in more arguments than not it seems like the opponents don’t even understand each other’s positions. I don’t think I am so much better than all of the other voices out there – but I want to try to be. I think we all must, if we are to bring more civility and substance to the rhetoric of our times.

So that is the main purpose of this blog: to explore my beliefs and my reasons for holding them, and in doing so, to hopefully encourage rational thinking. A secondary purpose that I want to accomplish is to show how I can construct my whole belief system from the ground up.

Of course, when constructing a belief system from scratch, the temptation to avoid is to simply take the beliefs I already hold and support them however I can. What I hope to show instead is that the beliefs that I have come to hold, after evaluating the options, are the ones that I have found to be the most rational. That is the goal: not simply to prop up my own beliefs, but to conform my beliefs to the truth.

Building the Foundation

Before I can construct a belief system, though, I need to lay its foundation. Trying to do that raises some deep questions:

  • What does it mean to believe something, and when is it reasonable to do so?
  • What kind of beliefs do we want to hold?
  • What is knowledge? How can we know things?
  • What is truth?
  • What is the nature of reality?

Yes, when I said foundation, I meant all the way down. Though philosophers have pondered these questions for millennia, I will begin by attempting to answer them. But before I do that, let me say a bit more about how I want to approach this, in my next post.