Tuesday, March 30, 2021


I used to read the Proverbs a lot when I was a kid and into my 20's. It was one of my favourite books in the Bible. I thiink everybody should read it whether they are a Christian or not, because it can inspire you to be a more virtuous person. You may not even agree with all of them, but you can still get something out of it.

The Proverbs have something for everybody. I think almost anybody who reads the Proverbs will find some that address their own vices. So if you're lazy, dishonest, prideful, stubborn, unreasonable, prone to anger, or you talk too much, there's a Proverb for you.

The other day, I was feeling angry about something. I don't remember what it was. But I was so rattled, I read Proverbs 10 through 30 in one sitting. There were lots of Proverbs about anger. For example, "A fool shows his annoyance at once, but a prudent man overlooks an insult." Reading things like that make me want to be the wise man. I find it calming. It gives me that extra incentive I need to strive to be patient, slow to anger, etc.

So I highly recommend reading the Proverbs. You are bound to find yourself in there somewhere. When I was younger, I would put a mark besides some of the Proverbs that jumped out at me, and I'd go back and read them later. Sometimes I'd quote them in discussions with other people, and eventually I'd have them memorized without even trying. Memorizing them brings them to mind whenever there's a situation in the real world where they apply.

The only liability with reading the Proverbs is that sometimes you recognize not only yourself, but also some of your family and friends. That can lead you to be judgmental. So you have to be careful with that. Otherwise, it's a great collection of Proverbs, and I highly recommend it.

The first time I read the Proverbs, it was in the NIV. I memorized a lot of them in the NIV, but then I read them in the NKJV. I had one of those little New Testaments they pass out on college campuses that include the Psalms and Proverbs. I used to sneak it to work with me and read the Proverbs when I could. I ended up memorizing a lot of them in the NKJV, too. Now-a-days, I read the NASB. Some of them aren't quite as pithy or memorable in the NASB. That may just be because they're not what I'm used to. I don't know. But it seems easier to read them in the NASB and not be sure what you just read. But give it a go, whether you have the NASB, ESV, NIV, RSV, NRSV, or NKJV, you'll probably get something valuable out of it.

Friday, March 19, 2021

Catholic Tradition

Whereas Protestants think the Bible is the only source of God-breathed information available to the whole church, Catholics think both the Bible and Tradition are God-breathed sources of information available to the whole church. Tradition is supposed to exist alongside the Bible and be equally authoritative.

Let's grant for the sake of argument that there was an oral Tradition in the early Church that was every bit as authoritative as the written scriptures. It's not an unreasonable thing to believe because (1) we know there were oral Traditions because some of them are quoted in the New Testament (e.g. 1 Corinthians 11:23-25 & 15:3-5), and (2) Paul tells the Thessalonians to hold firm to the Traditions they were taught whether by word of mouth or by letter (2 Thessalonians 2:15). I get the impression from passages like 1 Corinthians 11:2, 2 Thessalonians 2:15, and 2 Thessalonians 3:6 that oral tradition was the primary way Paul conveyed essential Christian doctrines to the churches he established. The letters always came after the new Christians had already been taught what Christianity was all about. Paul sometimes quotes oral traditions to remind people of what they had already recieved. There were probably a lot more oral traditions than what got quoted in Paul's letters. So I don't think it's unreasonable to believe that besides the written words of the Bible, there is also an oral Tradition that's just as authoritative.

But that isn't any reason to think Catholic Tradition carries the same authority as the Bible. In the case of the Bible, if we want to know what was originally written, we have to use the tools of textual criticism. Thankfully, we've got lots of copies we can compare, and that allows us to reconstruct with a good degree of confidence what was in the originals. But whatever oral Traditions there were in the first century obviously weren't preserved in the same way or even in an analogous way. If they were, we should expect the Catholic Church to be able to give us a written collection of these oral traditions. Or, if we accept the Catholic idea of apostolic succession, we could ask all the Bishops of the Catholic church to write down the oral traditions they received, then we can compare them to each other and reconstruct the original wording.

But it looks like none of the oral Traditions that supposedly existed were preserved in their original wording. The wording is completely lost. Now, what the Catholic Church appears to mean by "Tradition" is not a fixed memorized oral Tradition, but an interpretation of those original oral Traditions. The doctrines of the Catholic church, however they are explained and conveyed, are supposed to capture what the oral Traditions taught. How can we know that the interpretation is correct if we can't go back to the original wording? In the case of the Bible, we can at least go back to the original wording if we want to settle disputes about interpretation.

Well, it turns out that the Catholic Church claims to have interpretative authority that applies both to Tradition and to Scripture. I'll come back to this in a minute.

The idea that Tradition has been preserved in an oral form by passing it down from one Bishop to another or one Pope to another is a myth. There are no fixed oral traditions in the sense that Paul quoted them in the New Tesatment. They are all lost. All we have are the Scriptures. And besides that, if there were some fixed collection of oral Traditions that were accuratedly passed down from one Pope to the next Pope, we should expect more uniformity from Pope to Pope. The reality is that there have been Popes who were heretical. There's no point at which an out-going Pope sits down with an in-coming Pope and hands down oral Traditions they received from the previous Pope. That doesn't happen with Bishops either. Usually, a Pope dies, and the Cardinals vote a new Pope in, so the out-going Pope doesn't even know who the in-coming Pope is going to be. How can they pass down Tradition in the idealized way Catholics portray it happening?

It is hard to look at the history of the Church and believe there was this unbroken passing down of a fixed oral Tradition that's just as reliable as the written words of Scripture.

Nevermind for the moment whether Sola Scriptura is theologically correct. It strikes me as being necessary on a practical level. We know what the New Testament originally said because of how it was preserved. We have nothing comparable with oral Tradition. So even if there was oral Tradition that carried the same weight as Scripture in the earliest years of the Church, that oral Tradition is lost. It's possible that some of the teachings of the Catholic Church are reflections of an ancient Tradition that used to be passed on by word of mouth, but there's no way to confirm it with any degree of confidence. Without being able to confirm it with any degree of confidence, it can't carry the same authority as Scripture.

Catholics trust both oral Tradition and the written scriptures because of a third source of authority, namely the teaching magisterium of the Church itself. But why think the Catholic Church has this authority? Well, that's because of Scripture and Tradition. Yes, it is circular reasoning, as I explained in this post.

Catholics think Sola Scriptura is problematic because before you can know which writings are Scripture, you need an outside source of authority. They have the Church, but the protestants don't. This assumption is what leads Catholics to circular reasoning. If you need one source of divine authority in order to tell you about another source of divine authority, then you've either got to engage in circular reasoning or else an infinite regress of divine sources of authority. The only way to break out of that is to argue for a divine source of authority using premises that are not divinely inspired. That's essentially what protestants do. When the church tried to settle disputes about canonicity, they used arguments, not fiat. Protestants accept the canon because we believe the best arguments won out, not because the Church is infalliable. If Catholics try to establish the authority of one of their sources (the Bible, Tradition, or the teaching magiesterium), not by appeal to another source of divine authority, but by using reason, evidence, and argument, then they are basically arguing like protestants, and they have lost their basis for objecting to Sola Scriptura or for saying potestants can't know the canon.

James White accuses Catholics of subscribing, in practice, to Sola Ecclesia--the Church is the sole infalliable rule of faith. I think he's got a point. From a Catholic point of view, it all goes back to the teaching magisterium of the Church. That's what tells us what writings are Scripture, what they mean, and what is contained in Tradition and what it means. If Scripture and Tradition are subordinate to the Church (since the Church determines what Scripture and Tradition are and what they mean), then for all practical purposes, Catholics subscribe to Sola Ecclesia. But, as soon as they try to establish the authority of the Church by appealing to Scripture and Tradition, they are engaging in circular reasoning, and I'm not sure you can accuse them of Sola Ecclesia anymore.

If we accept the divine authority of the teaching magisterium of the Church, then the accurate preservation of Scripture and Tradition shouldn't matter that much. The Church knows correct doctrine even if it has forgotten the original wording. As far as I know, the Church doesn't claim to have an infallible critical text of the New Testament. They still rely on secular fallible means of preservation. We can know the original wording only insofar as we can use textual criticism to reconstruct it, and the Church doesn't claim this process is infallible. All they claim that's infallible is what the Church claims the Scriptures teach. But just as they lack the original wording of the oral Traditions and have preserved only the teachings supposedly contained in those Traditions, so also could they preserve the teachings of the New Testament without having the actual New Testament. The wording of the New Tesatment is really secondary when it comes to sound doctrine. It all basically comes down to what the Catholic Church teaches, and not to the original wording of the Bible or the oral Traditions. That's Sola Eccelsia.

I had more to say, but after taking a break, I've forgotten what it was. Maybe I'll edit this post later if it comes back to me.

Tuesday, March 16, 2021

Knowingly doing something wrong

There have been a handful of times when I've run into somebody who could not wrap their head around the idea that somebody would do something wrong if they knew it was wrong. Two of them thought it was impossible. Just as they could not wrap their heads around such a thing, I could not wrap my head around how they could think such a thing. It seemed obvious to me that people can knowingly do what is wrong. I've done things I knew were wrong. Who hasn't? I remember talking to somebody about this a couple of years ago, and both of us were dumbfounded at each other. It made me wonder if there was some big misundertsanding going on. How could he be unaware of something that was so obvious to me? Or how could I be unaware of something that was so obvious to him?

Anywho, I was just watching This Crime Watch Daily video on YouTube about a murder for hire plot. There was one part of it that caught my attention. The woman who was hiring an undercover cop to kill her husband said, "This is such a horrible thing to do," and yet there she was doing it. Clearly, she was doing something wrong, and she knew it was wrong.

If you are reasding this, and you are one of those people who doesn't think a person can knowingly do something they think is wrong, can you explain this to me? I feel like there's something I'm missing. Nevermind the fact that I disagree with it. I wonder if I've just got some kind of misunderstanding about what people mean when they say they hold this position because it seems so obviously and demonstrably false to me.

Saturday, March 13, 2021

Thomas Crisp's evolutionary argument against naturalism

There's this new YouTube channel called Parker's Pensées, and he has some excellent content. Earlier today, I watched this video where he interviewed Thomas Crisp and Tyler McNabb. They talked about an article Thomas wrote for The Blackwell Companion to Naturalism. I googled Thomas Crisp and found the article: "On Naturalistic Metaphysics" I just finished reading it and thought I'd share my initial thoughts.

I only read it one time, so this is an off-the-cuff response. I may feel differently about it if I read it some more and think about it, but here's my thoughts for now.

Whereas Plantinga said that given naturalism and evolution, the probability that our belief-producing cognitive faculties would be reliable is low or incrutible, Crisp made a more modest claim. He didn't claim that all our beliefs would be unreliable, but that certain kinds of beliefs would be unreliable. He said the probability that our belief-producing cognitive faculties would give us reliable abstract metaphysical beliefs given naturalism and evolution is inscrutible. The reason is because we haven't evolved significantly from when we were cave men, and those kinds of beliefs would've been completely useless to our cave man ancestors. This avoids a certain criticism that Plantinga's argument has gotten--that surely we'd be better off with true beliefs than false beliefs. In the case of abstract metaphysical beliefs, that's not the case since they lack any practical application for cave men.

Well, naturalism is an abstract metaphysical belief, and it requires a high level of thinking to arrive at it. If our cognitive faculties are unreliable when it comes to these kinds of questions, then we can't rely on them to tell us that naturalism is true. So if naturalism is true, then we can't be rational in affirming it.

That's the arument in a nutshell. He did go into possible responses, but I'm not going to address those since I have my own responses.

My initial impression is that it's an interesting argument worth thinking about, but I'm not totally persuaded just yet. I have a few objections.

First of all, it seems to me that with just a little bit of imagination, we might be able to come up with an evolutionary advantage to having the capacity for abstract metaphysical reasoning. Maybe being able to do philosophy could help you reproduce since "smart" has always been sexy. Suppose we can't come up with a use for it, though. Wouldn't that have more to do with our lack of imagination than with there not being any use for it?

Second, I don't see that it requires a great deal of abstract thinking to arrive at naturalism. All naturalism requires is that you believe what you see and don't believe what you don't see. All we see is physical stuff, and it's easy to see why, on naturalism, we'd believe in it. But the belief that that's all there is doesn't require much abstract thinking it seems to me. It would seem to me that supernaturalism would be less likely than naturalism since supernaturalism requires belief in things we don't usually experience.

Third, abstract metaphysical thinking and reasoning is actually hard, which is what we would expect if evolution is more concerned with practical beliefs that affect our every day lives. The fact that it's hard is evident in the diversity of opinion among brilliant people on metaphysical questions. So maybe our metaphysical beliefs aren't that reliable. Or maybe it just takes a lot more effort to arrive at true conclusions when it comes to metaphysics because evolution didn't equip us that well for thinking about those kinds of things.

I still think Plantinga's argument is better. Plantinga's argument relies on the premise that naturalism leads to semantic epiphenomentalism. As long as that argument goes through, then Plantinga's EAAN is sound. For the time being, I'll stick with that. But if you want to talk about this new argument, you might ought to read the article by Thomas Crisp first. There's more to it than what I've explained, and it's always possible I missed some stuff or misunderstood some stuff. I'm more curious what you think about his argument the way he explained than how I explained it after a first reading. I'm also curious what you think of my objections after reading his paper and if you have any objections of your own. Or do you think it's a sound argument?

Monday, March 08, 2021

What is consciousness?

I always find it odd when I hear people say, "We have no idea what consciousness is." Unless you're a philosophical zombie, you know exactly what consciousness is because you experience it directly. It's the one thing you can't be mistaken about.

Maybe what people mean is that they don't know what causes consciousness or what the underlying physical mechanism is. There's got to be some kind of misunderstanding going on. I used to think maybe it was just in the difficulty of giving a precise definition of consciousness. There are a lot of words that are hard to define but that we nevertheless have no problem understanding. Maybe consciousness is one of them.

If you are a philosophical zombie, maybe I can help. Consciousness is first person subjective experience. Hmm. I guess if you're a philosophical zombie that probably isn't any more clear. I tried, though.

Friday, March 05, 2021

A PhD in Christian apologetics

I only found out a few years ago that there were PhD programs in Christian apologetics. I knew there were MA programs. I figured those MA programs existed either for personal edification (Christians just want to have a deeper grasp of Christian apologetics so they can be better apologists in their ordinary lives) or to prepare people to go into an apologetics ministry. Nothing about that struck me as weird.

But when I found out that there were PhD programs, it did strike me as being weird. There are two reasons.

First, when I think of a PhD in some field, I think of somebody who is an expert in some specific subject, like physics, history, philosophy, or whatever. But apologetics is an interdisciplinary field that borrows from physics, history, and philosophy. If, hypothetically, a PhD program were divided evenly between those three fields, then a PhD in apologetics would have about 1/3 of the exertise in any of those fields as somebody who had a PhD in one of those fields. So, if a PhD in apologetics were to try to do research in one of those fields so as to publish a paper and contribute to the scholarly conversation, they would be severely handicapped. It just strikes me as being weird that there would be a PhD program for such a generalized field when PhD programs are usually very focused on a narrow field of interest.

Second, in just about every other field of inquiry where you could get a PhD, the purpose is to contribute to answering questions in that field. In Physics, you want to know the laws of nature--how the universe operates. In Philosophy, you want to answer the big questions and maybe gain a deeper understanding of past thinkers. In History, you want to find out what actually happened in the past and why. But in Christian apologetics, you already have the answer to the big question--Christianity is true and competing worldviews are not. The only question is how to prove it. So, in what sense is it really a field of inquiry? Maybe you could think of it as an inquiry into the history of apologetics literature and the authors and arguments involved, but in that case, why not call it a PhD in Christian rhetoric? If it were Christian rhetoric, you wouldn't have to be committed to the conclusion that Christinaity is true, and anybody could get a PhD in it whether they were Christians or not. But to have a PhD in an academic field that only exists because of already having an answer to the major question in that field strikes me as being weird.

Why would anybody even want a PhD in Christian apologetics? Who is qualified to awared somebody with a PhD in Christian apologetics? What kind of scholarship does having a PhD in Christian apologetics allow you to produce that you couldn't produce better by having a PhD in some other field, like physics, biology, philosophy, or New Testament history?

The only person I know of who has a PhD in Christian apologetics is Sean McDowell, although I'm sure there are others. He did his dissertation on the question of whether the disciples of Jesus died as martyrs. That strikes me as being an historical question, and somebody who got a PhD either in New Testament or early Christian history or something along those lines would be far more equipped to do that kind of research. I wonder if Sean's PhD even involved him having to learn ancient languages like Greek and Latin in order to delve into the primary sources like a scholar in ancient history ordinarily would.

I'm curious if Sean has published any scholarship in any professional journal. I was just looking at his CV, and it shows a lot of books he either wrote or contributed to. With the possible exception of The Fate of the Apostles they look to all be popular level books. The Fate of the Apostles is published by Rutledge, which does publish some academic books, but has Sean's book been peer reviewed? Does any PhD in Christian apologetics contribute to professional journals? If so, what kind? I have a hard time imagining somebody with a PhD in Christian apologetics doing original research in physics, cosmology, biology, etc.

I don't mean this post to be a criticism of a PhD program in Christian apologetics. I don't even know what's entailed in the program. I am just expressing my own impression that it seems weird. It isn't like a PhD program in any other field that I know of.

Wednesday, March 03, 2021

An argument for Christianity

I've never laid out my full case for Christianity (although I'm writing three books that do that, and I'm almost finished with one of them) until now. Starting on January 1, 2021, I started a new YouTube channel called Introverted Christian. I made 50 videos and just finished the last one today. With the exception of the introductory video and the third video, they are all part of my argument for Christianity.

First, I talked about epistemology. Then I talked about idealism vs. naturalism vs. dualism. Then I gave arguments for the existence of God. Then I made an historical case for Jesus claiming to be the messiah, then rising from the dead. Finally, I made a video tying it altogether and making my case for Christianity.

But don't expect anything great. I did these videos almost entirely off the top of my head. The reason is because defending Christianity was secondary to my main purpose which was to improve my ability to speak. You see, over the last several years (especially the last three), it has become increasingly difficult for me to talk plainly and clearly without stuttering over my words, losing my train of thought, and just getting my words out. About two years ago, Kyle Hendricks interviewed me on his podcast. I was not at all happy with how it went, and it got even worse when I listened to his other interviews. The other people spoke clearly and smoothly, and it really embarrassed me because of how terrible I was at speaking. So I decided to fix it.

Originally, I was going to do my own podcast, but I put it off for a long time and finally decided to do a YouTube channel instead. I wanted to do a bunch of videos where I just monologued so I could hopefully overcome my inability to speak. I decided to do Christian apologetics because that's the one thing I can monologue about.

I did it all off the top of my head because the object was to learn how to speak clearly and fluently without losing my train of thought, or misspeaking, or using the wrong word, or not being able to think of words, etc. Using notes or an outline would be like using a teleprompter, and we've all seen how the use of a teleprompter can make a huge difference when certain politicians are speaking. I didn't want to cheat because that would defeat the purpose.

So the quality of these videos is pretty bad. I do lose my train of thought, I struggle with how to word things or explain them, I often can't think of words or think of what I was going to say, and sometimes I'll use the wrong word without even realizing I did it until editing the video later. In some cases, I would edit out my long stairs into space or my stuttering or whatever. But sometimes I would leave them in for the sake of transparency. Sometimes, if I accidentally used the wrong word or couldn't think of a word, I'd write it in during editing so you can see it. There are a few factual mistakes I made because I was doing it off the top of my head. Sometimes I'd make corrections on the screen, but sometimes I'd just let it go.

So, those are my disclaimers. If you are interested, you can go watch those videos. I made some playlists to make it easier for people to watch things in order. The whole series is meant to be one sustained argument for Christianity. In other words, the videos are not meant to be stand-alone videos. Each one builds on the ones that came before, and they're all important to my overall case.

I made two videos by way of introduction and explaining my problem:

Introduction to the Introverted Christian channel

Speaking as a socially anxious and introverted Christian

I made a few playlists, and there is overlap between them. For example, all the stuff in the playlist on the moral argument are also contained in the playlist on the arguments for God, and then again in the playlist for the whole argument for Christianity.

This playlist is the entire 48 video argument for Christianity in the correct order:

An argument for Christianity

This playlist contains all of my videos on epistemology


This playlist contains all my videos comparing and contrasting the three worldviews: idealism, naturalism, and dualism. I defended dualism.

Idealism vs. naturalism vs. dualism

This playlist contains all my videos on the Kalam Cosmological argument.

The Kalam cosmological argument

I also made videos on the argument from contingency, biological complexity, fine tuning, and the ontological argument, but I didn't make playlists for those since I did them in single videos. They are included in the playlists for the existence of God and for the overall argument for Christianity. I didn't necessarily endorse all these arguments. I just talked about them.

This playlist contains all my videos on the moral argument.

The moral argument

This playlist contains all my videos on the arguments for God together.

Arguments for God

This playlist contains all my videos on the Bible as an historical source.

The Bible as an historical source

This playlist contains all my historical arguments about Jesus (e.g. his claim to be the messiah and his resurrection from the dead).

Arguments for the christology and resurrection of Jesus

And finally, there's my last video that ties everything together, gives my final argument for Christianity, then briefly explains the gospel, the practical implications, and makes an argument for the divine authority of the Bible and the deity of Jesus.

An argument for Christianity

And that's about it. During the course of recording these videos over the last two months, I began to change my mind about what the cause was for my speaking problem. Originally, I thought it was all due to my social anxiety and my lack of social interaction (especially since the pandemic). But now I'm beginning to wonder if I have aphasia. If it's aphasia, I'm afraid doing this kind of thing probably won't help. During the course of shooting these videos, I became a lot more comfortable talking in front of the camera, but I really don't think I made much improvement at all in my ability to speak smoothly. It's very discouraging. But I am proud of having finished it. There are a few videos where I used short lists so I wouldn't have to rely entirely on my memory, but for the most part, I did this whole thing off the top of my head. While I'm happy with having gotten through all that, like I said, the quality is lacking, so don't expect much. Hopefully my books will be better if I ever finish them.

Tuesday, March 02, 2021

When are we justified in saying something is possible or impossible?

I saw a clip with Matt Dilahunty yesterday in which he was telling a caller to his show that if somebody says something is possible, they have to demonstrate that it's possible just as somebody would have to demonstrate impossibility if they said something was impossible. My initial reaction was to disagree with him because it seemed to me the default position in most cases is that we should think something is possible until it is demonstrated to be impossible. I was thinking of logical possibility and impossibility at the time. Unless some scenario is contradictory, then it's logically possible. Logical possibility only requires that there not be any contradictions, so as long as no contradictions jump out at you, you're warranted in thinking it's possible. With that in mind, you shouldn't have to demonstrate possibility since to demonstrate possibility, you'd be required to demonstrate a universal negative--there are no contradictions. It seemed to me that as long as no contradictions presented themselves to you, that's all that's required for you to be justified in thinking something was possible.

That was my initial reaction. But there are different senses in which we say things are possible or impossible. Logical possibility/impossibility is just one of them. There's also physical possibility/impossibility. But when is something physically possible or impossible. At first, it would seem that something is physically impossible as long as the laws of nature allow for it and it doesn't violate any of the laws of nature. But consider the question of whether it's physically possible for me to outrun a healthy cheetah. That seems physically impossible, not becuase it violates any of the laws of nature, but because I lack the physical strength in my legs or whatever. I'm not sure how to characterize that. Maybe we could say something is physically possible as long as (1) it doesn't violate the laws of nature and (2) you have the physical conditions to bring it about. If there were just that first condition, then I would think physical possibility/impossibility would be just like logical possibility/impossibility as far as whether there's a default position or what that position is. But given that second condition, that woudl seem to place a higher burden of proof on somebody who claimed that somethign was physically impossible. You'd have to demonstrate or explain somehow why my legs are incapable of allowing me to outrun a healthy cheetah. After all, for all we know, there may be animals in the future that will be able to outrun cheetahs. Maybe gazelles already can sometimes.

Another difficulty with physical possibility/impossibility is that whereas we probably have the basic laws of logic nailed down (especially the law of non-contradiction which is the most important one when it comes to possibility and impossibility), the laws of nature are a bit more complicated. We don't know all the laws of nature, and the laws of nature we do know are only provisional. Take general relativity for example. It does a good job of explaining most things. But we know it can't be the whole pictures because it predicts singularities which are physically impossible. So we know it breaks down at some point and we need a new theory to explain those cases. General relativity is, at best, an approximation. Since we don't know all the laws of nature, it's harder to say whether things are physically possible or impossible. General relativity makes it seems like backward time travel is physically possible, but it may be physically impossible due to unknown laws of nature. (Nevermind whether it's logically possible.) So it seems like physical possibility would have to be demonstrated or justified in some way even if logically possibility doesn't.

There's a third kind of possibility--epistemic possibility. A thing is epistemically possible or impossible when it's possible or impossible for all we know. You could say that backward time travel is possible for all we know as long as there's no reason to think it's impossible. In that case, there doesn't seem to be a big burden of proof for somebody who claims it's possible. As long as there are no known laws of nature that prevent backward time travel, that's enough to say backward time travel is possible for all we know.

What do you think about all this? Do you think the claim that something is possible carries the same burden of proof as the claim that something is impossible? Does it depend on the kind of possibility we're talking about? In general, how would you go about showing that something is possible, whether logically or physically or in some other sense? Does it require demonstrating a universal negative--that there's nothing to make it impossible? Do you think there are ever default positions to certain questions in which we should assume one thing is true until it is shown to be otherwise?