Sunday, 16 September 2012

WLC takes us for a ride

I first heard of the “Taxi-Cab Fallacy”, invoked by William Lane Craig while debating against Lawrence Krauss.  Follow me on a journey of discovery to see what this term means.  Once we arrive at an idea of what it means, we can look to see if Craig’s opponents really are guilty of committing it.

Craig first makes reference to the “Taxi-Cab Fallacy” in his first rebuttal:

He says, “Well, is the universe contingent? Perhaps the universe doesn’t exist necessarily.” My argument was that the universe doesn’t exist necessarily, that it’s contingent in its being. Scientists regularly discuss other models of the universe that are logically possible, universes governed by different laws of nature. And clearly the universe is not ultimate in the sense of being self-explanatory. And you can’t say that it’s contingent and yet ultimate-without-explanation because that would be arbitrary and unjustified. It commits what’s been called the Taxi-Cab Fallacy, which is thinking you can dismiss the need for explanation when you arrive at your desired destination. And it’s simply arbitrary to apply the explanatory principle everywhere else in life but then deny it when you get to the existence of the universe itself.

This Taxi-Cab Fallacy doesn’t seem to exist outside of Craig’s world (Christian Apologetics), so nailing down precisely what it means is a little difficult.  When Craig uses it in this context, it’s not totally clear what he means.  Note that he makes reference to “the explanatory principle”.

Later in the debate, in the second rebuttal, Craig invokes the “fallacy” again:

What about the first point of evidence that the existence of contingent beings is more probable on God’s existence than on atheism? He didn’t deny the point. Remember, I explained, to deny the explanatory principle of the universe is to commit the Taxi-Cab Fallacy: it’s arbitrary and unjustified.

O-kay.  This is no explanation either.

Craig calls on it again, in his closing speech:

First of all, we looked at the existence of contingent beings, and I explained that given the existence of God, it is more probable that contingent beings would exist than on atheism because on atheism there is no explanation for the existence of contingent beings. And to try and say that there need not be an explanation for the existence of the universe is arbitrary and unjustified. It commits the Taxi-Cab Fallacy. So I think the very existence of contingent beings makes God’s existence more probable than it otherwise would have been.

Hang on, are we talking about the existence of “contingent beings” or “the existence of the universe”?  Craig veers wildly between the two.

The universe exists and we know that because we are in it.  Our lack of an explanation for the universe clearly doesn’t prevent us from being here anymore than an inability to explain cosmology affects existence of slugs.  Craig seems to be arguing for a God on the basis that our having an explanation for the universe (that is, God) would make the existence of contingent beings (that is, us) more probable.

But Dr Craig, just in case you haven’t noticed … we exist.  The probability of us existing, given that we are doing the calculation of the probability, is 100%.  The probability of us existing is:

·         100% if God made us

·         100% if the Flying Spaghetti Monster made us and

·         100% if we arose due to processes entirely consistent with materialism

Only if you were a God, sitting outside the universe making these calculations could you arrive at any other probability.

But, back the “Taxi-Cab Fallacy” …

In the closing speech, Craig fails again to clarify what he means by the term.

In the Q&A session, Craig invokes the “fallacy” one last time:

Well, what’s lazy is to stop arbitrarily when you get to the universe. That’s what’s committing the Taxicab Fallacy: to accept the Principle of Sufficient Reason everywhere else until you get to the universe, and then arbitrarily stop there. The theist doesn’t arbitrarily stop when he gets to God as the explanatory ultimate. God has an explanation of his existence. “Everything that exists has an explanation, either in the necessity of its own nature, or (if it’s contingent) in an external cause.” God exists by a necessity of his own nature. Even the atheist recognizes that. If a being has a cause, it isn’t God because God by definition is the metaphysical ultimate. So when you get to God, you’ve reached a metaphysically necessary being which has no cause of its existence, and its existence is explained by the fact that it exists by a necessity of its own nature, just like mathematical objects and other abstract objects. And that’s why you don’t run into the slushy crush or whatever it is that you were talking about. It would be logically impossible for God to be caused by slushy crush or whatever it is.

At this point, Craig has still not explained his “fallacy” properly.  What he has done, however, is to make reference to the “Principle of Sufficient Reason” (which he also fails to explain, but we can look up) and exposed what he probably means by invoking the “fallacy”.

This was my thesis: Craig meant that for an atheist (and a materialist), the metaphorical “taxi-cab” is the use of science and materialism to explain everything.  The atheist likes to use this explanation all the way up to the existence of the universe, which is the metaphorical “destination”, but then the atheist will say, metaphorically, “I got here using the taxi-cab (science and materialism), but I don’t want to use it anymore, I want to switch to a new argument”.


A little more on the origin of the fallacy and then we can look to see if its use has been appropriate.

If you use Google and limit the search to before the end of 2007, you can find the first appearance of the term – William Lane Craig’s website (we will get to it shortly).  If you widen the search out to the end of 2010, there will be two websites with the term, but the second is a blog which has a mention of the “fallacy” only in a comment which was posted towards the end of January 2011.

2011 was a golden year for the term, with a total of maybe a dozen new sites referring to the fallacy – Google seems to say more but a couple of blogs inflate the numbers significantly such as and  This year, 2012, has seen another dozen or so appearances (of which, this shall be another).

Tip for those who are new to Google, click on the last o in Gooooooooooogle and do it again.  At the time of writing, rather than approximately 19700 mentions (shown just to the right of the word “Search” in the top right hand corner), you end up with 121.  You can then click on the “repeat the search with the omitted results included” (at the bottom of the last page) to see an estimate of 8440 results.  Then repeat the clicking on the last o process and you arrive at a grand total of … 177 mentions.  This strange bouncing around of numbers seems to be a standard feature of Google’s search engine (you can get the same sort of result with “Loki is angry”, so it’s nothing to do with this particular search string).

The bottom line with this is that Craig’s fallacy is poorly known, despite the apparent 19,700 mentions that a na├»ve use of Google implies.  Craig should have clearly explained what he meant by the term.

The extent of Craig’s dishonesty is already apparent in the first appearance of the fallacy, which was phrased as a response to a reader’s question (it might have been Craig himself though, the fellow being called “William”).  Craig says:

Premise 1 is the premise that the atheist typically rejects. Sometimes atheists will respond to premise 1 by saying that it is true of everything in the universe but not of the universe itself. But this response commits what has been aptly called “the taxicab fallacy.” For as the nineteenth century atheist philosopher Arthur Schopenhauer quipped, premise 1 can’t be dismissed like a hack once you’ve arrived at your desired destination!

(He’s referring to the first premise of his Cosmological Argument from Contingency:

1. Everything that exists has an explanation of its existence (either in the necessity of its own nature or in an external cause).)

But hang on, “has been aptly called “the taxicab fallacy”?  By who?  This is the very first appearance of the fallacy.  But to be fair, he sort of attributes it to Schopenhauer (more about that in a later article).

Craig’s first use seems to be consistent with my thesis.  But being a thorough sort of person, I looked for a better explanation, which I found in the second direct appearance of the fallacy at Street Apologetics – led by Greg Laurie, who holds an honorary doctorate from Biola University, which just happens to be Craig’s University:

The “Taxi-Cab Fallacy” is committed when one hops in and assumes a certain system of thought or worldview in an attempt to make a particular point but then jumps out of the system of thought when it suits their fancy. Such practice lacks logical consistency and is therefore a logical fallacy.

A detractor of the Christian worldview cannot hop into the Christian system of thought by erecting an objection grounded in the Bible and then demand an answer be given without the use of a Bible. Again, they cannot appeal to the Bible in raising their question and then insist we throw our Bible out of the equation when we give an answer!


Ok, we now have a verified definition of the “fallacy”.  It’s not quite how Craig is using it though, since here the “fallacy” seems to be related to asking for a non-Biblical explanation of an objection based on what is in the Bible.  Laurie’s version of the fallacy seems fair enough.  So long as an apologist never steps out of the Bible, and argues entirely within the narrative framework of the Bible, she is invulnerable.  No problems with that.

If she steps outside of the Bible, however, and tries to apply anything Biblical in the real world, she is fair game.

However, this is not how Craig uses the “Taxi-Cab Fallacy” in his debate with Krauss.  He implies that he is specifically talking about how atheists try to explain everything in the universe with science and then they switch arguments when it comes to the universe itself.  Are atheists guilty of this?


Put briefly, no.

But perhaps I am biased, so let’s not accept the brief explanation.

The trouble with Craig’s argument is the fact that the atheist doesn’t switch arguments.  At each and every stage up to and including the existence of the universe (which is notionally a question about the origins of the universe), the atheist can say and is fully justified in responding with “I don’t know” to a question if there is no evidence on which to base an answer.

There is no sudden change of tactics when arriving at the existence of the universe.

Also, science uses the evidence gleaned from the universe to explain things in the universe.  If we live in a universe which is part of a multiverse, then we can possibly explain more about the universe, because we are also in the multiverse.

However, if we live in a more classic universe which includes all there is, all there ever was and all there ever will be, then it is not possible to fully explain the universe using the universe.  Self-reference invariably opens the door to paradox, even if the self-reference is indirect.  For example, the next sentence is a lie.  The previous sentence is true.  This sentence, however, is certainly a lie.
So, the long answer is no.  Atheists would not be guilty of employing the “Taxi-Cab Fallacy”, even if there were such a fallacy


  1. Great post. A little while ago I tried to make sense of this "fallacy" as well. Ultimately I gave up as it seemed to me that WLC basically uses it as a catch all. I think he keeps it slightly ambiguous on purpose.

    You did a much better job looking up the history of this thing, I particularly like the google magic you worked. At the end we seem to have come to the same conclusion, this "fallacy" is BS.

    1. Thanks.

      It is worse than you thought though, as I explain further in the next article ... this was the fun bit. The next bit explains why Craig makes a lot of people angry.


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