Last Thursdayism (alternately Last Tuesdayism or Last Wednesdayism) is the idea that the universe was created last Thursday, but with the physical appearance of being billions of years old. It's also a counter to the creationism theory. Under Last Thursdayism, books, fossils, light already on the way from distant stars, and literally everything (including your memories of the time before last Thursday) were all formed at the time of creation (last Thursday) in a state such that they appear much older.

Last Thursdayism functions both as a philosophical point on how our observations may not match with "reality" and a reductio ad absurdum of the young-Earth creationist idea of the omphalos hypothesis: if the world was created 6,000 years ago with the appearance of being made billions of years ago, what is there to stop us from claiming it was made Last Thursday?

The debate on whether Last Thursdayism is true has raged on ever since the creation of the universe last Thursday.

(source: Last Thursdayism - RationalWiki)

In short, Last Thurdayism is put forward as an attempt to do a reductio ad absurdum of the Young Earth Creationist notion that the universe was created relatively recently with the appearance of age.

How do Young Earth Creationists go about showing that this attempt isn't successful?

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    I wonder if this theory is stronger or weaker now than it was when I heard it last week.... =) Commented Feb 28 at 3:08
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    "The 'reductio absurdum' is, itself, absurd as it is plainly false and can be dismissed without argument as a vain and foolish thesis." I don't follow you, can you elaborate why it is absurd, plainly false? Commented Feb 29 at 12:53
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    The idea that God had the Bible created with a false history to mislead us is no more absurd than the idea that he created light already on the way with only the appearance of being billions of years old to mislead us. (That is to say, both are absurd.) I write this as a Bible-believing Christian.
    – Ian Goldby
    Commented Mar 1 at 11:45
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    @NigelJ You still haven't explained why you think that Last Thursdayism is a "disgraceful insult to the Creator". Do you also consider that "the creation was created in such a way that it had the appearance of a long-functioning universe" is a disgraceful insult? If not, what, IYHO, is the essential difference that makes one an insult, but not the other?
    – user59106
    Commented Mar 2 at 7:19
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    Palpably and demonstrably false are LastThursdayism, LastWednesdayism and LastTuesdayism because the truth is LastFridayism. Commented Mar 4 at 18:30

4 Answers 4


IMHO, "last thursdayism" not only does not rebut the Creationist position, but strengthens it by illustrating the inability of science alone to make conclusive statements about history. While generally rejected as a serious hypothesis, it does go to demonstrate the impossibility of determining past events with certainty. Rather, historical investigation relies on assumptions and past testimony.

Some of these assumptions — for example, that the universe was not created 'last Thursday' — are philosophical. The Materialist assumption that no Creator exists is likewise a philosophical assumption. These assumptions cannot be verified scientifically; at best, we can say the evidence is consistent with them. By definition, the evidence will always be consistent with 'last Thursdayism', but almost no one gives that position serious consideration. In contrast, the evidence is poorly consistent with the absence of a Designer, yet a great many people do subscribe to that dogma.

It's worth asking "why?". Often, one finds that those holding to such position have philosophical objections to the existence of a Creator. But philosophical objections are a very poor basis for determining Truth.

Another point worth bringing up is the poor characterization of reality as described in the above quote. Specifically:

the universe was created last Thursday, but with the physical appearance of being billions of years old

The reality is that most of the universe does not appear billions of years old. In fact, there are only two lines of evidence that seriously point to such ages; that light from very distant stars is visible, and that evidence of significant radiometric decay exists. Both, however, have alternate explanations. The horizon problem already tells us that our understanding of how radiation propagates through the universe is incomplete. As for radiometric decay, while we can say with confidence that such-and-such amount of decay occurred, assigning a time over which it occurred is rife with assumptions, and there is much evidence that such decay in fact occurred over a very short period of time. In addition, the many inconsistencies and obviously-false results obtained in the field of radiometric dating similarly indicate that our understanding of the field is far from complete.

Nearly every other process alleged to take significant amounts of time has been demonstrated to occur extremely quickly under proper conditions, and in some cases, rapid occurrence is a more likely explanation than occurrence over long periods of time. "Millions of years old" fossils contain 14C, intact soft tissues, and even DNA. Ocean salinity, continental erosion, recession of the moon, and many other lines of evidence place a maximum age of thousands or tens-of-thousands of years on the Earth. Other processes similarly limit the ages of other planets. The rate of supernova (non-zero) compared to the rate of observed star formation (zero) suggests not only that the stars were not formed naturally, but recently.

It's true that there exists evidence which can be interpreted as implying millions or billions of years, but these are interpretations, and are almost always based on the a priori philosophical assumption that God does not exist. Despite media sensationalism, such beliefs cannot be proved, and a great many serious problems remain unsolved.

By comparison, those who believe in God have an eyewitness testimony of His Creation, which places the same at roughly 4,000 BC. Despite claims to the contrary (and billions of dollars spent), this history has never been falsified and is strongly consistent with the observable evidence with very few unsolved puzzles.

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    @Mark I'm puzzled how this is a good answer. The opening paragraph is simply untrue - "Last Thursdayism" does not demonstrate an inability to make statements about history, it merely demonstrates an inability to tell whether there was a history if a malicious entity has put enough effort into faking the starting point (which includes our own memories). The only assumption required is the continuity of time.
    – Graham
    Commented Feb 29 at 19:04
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    @Mark ... As regards the last sentence, this is not only untrue, it is so untrue that it literally requires the active rejection of a large plurality of evidence. Can we prove a negative? No. Does every piece of evidence ever gathered on the subject point to the Young Earth claim being either false or at the very best unproven? Yes.
    – Graham
    Commented Feb 29 at 19:14
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    @Graham, you seem to be conflating the concepts of true and apparent history. If we have "an inability to tell whether there was a history", then any statement about history is necessarily uncertain (or, as I wrote originally, "inconclusive"). As to "no scientist, as part of their subject matter, makes an assumption that God does not exist"... fine, but "exist" and "participate" is a gratuitous quibble that is effectively without distinction.
    – Matthew
    Commented Feb 29 at 19:17
  • Let us continue this discussion in chat.
    – Matthew
    Commented Feb 29 at 19:36

I'm not a Young Earth Creationist, but from the YEC perspective it is very straightforward to reject "last Thursdayism".

YEC derives the age of the universe not from the light of distant stars, extrapolating expansion backwards, or other uniformitarianism-based arguments, but from the Bible. The YEC position is not that God couldn't have created the universe last Thursday, but that He didn't, based on what He revealed in Genesis.

There are those who read the Bible and conclude that the universe is something times 10^3 years old. Others come up with something times 10^4 years. Others come up with larger numbers. But there is literally nobody claiming that the Bible supports a creation of the universe last Thursday.

In order to successfully argue a reductio ad absurdum it is necessary to accept, for sake of argument, the premises of one's opponent. The "last Thursdayism" argument fails because it does not do so. It selectively accepts the "created with the appearance of age" premise while rejecting the premise that Genesis is revealed truth.

[from a YEC perspective] what is there to stop us from claiming it was made Last Thursday?

The Book of Genesis.

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    Comments have been moved to chat; please do not continue the discussion here. Before posting a comment below this one, please review the purposes of comments. Comments that do not request clarification or suggest improvements usually belong as an answer, on Christianity Meta, or in Christianity Chat. Comments continuing discussion may be removed.
    – Peter Turner
    Commented Mar 2 at 17:48
  • Just curious, what's stopping you from being a YEC? Do you think a strong case can be made against YEC?
    – Mark
    Commented Mar 7 at 17:36
  • @Mark you want me to tackle that one in the comments!?! =) Commented Mar 7 at 18:34
  • @HoldToTheRod How about the chat above?
    – Mark
    Commented Mar 7 at 18:35
  • @Mark - I shared a few thoughts but apparently it doesn't let me tag you there. Commented Mar 9 at 2:48

Not a YEC myself, but I see major problems with using Last Thursdayism as presented here to level a reductio attack on YEC.

In the first place, there is a problem with the origin of false memories. If the universe were created last Thursday, just looking really old, then I really do have false memories. How and why do I (and literally everyone older than a week) have false memories? How is it that my wife and I share many identical memories that are (or appear to be) years old at this point? And not only general memories, but very specific ones. I can tell you where my parents sat at our wedding, as can she. I can tell you what wine we had on our first date, as can she. Why do animals around us also appear to have memories? Why does my dog know what sit means? Why did he know what it meant last Thursday, at the moment he was supposedly created? I remember teaching him to sit years ago. The Last Thursdayist has a much tougher job to do in explaining this phenomenon than the YEC, because the YEC doesn't claim that anyone has false memories. The universe was created in media res, and only then was man introduced, on the sixth day.

Another problem is that YEC is rooted in a certain and somewhat common interpretation of Sacred Scripture. While that may not mean much to an atheist, it should to a Christian. Unless a competent authority has explained how and why such an interpretation is incorrect, as may be done at Church Councils, the interpretation is open for belief among Christians. Last Thursdayism does not derive from any sacred texts, Christian or otherwise, and so has less objective support.

In short, I think Last Thursdayism, at least as presented above, comes with its own additional difficulties that YEC does not come with, and that YEC has historical and textual support that Last Thursdayism lacks.

  • Just curious, what's stopping you from being a YEC? Do you think a strong case can be made against YEC?
    – Mark
    Commented Mar 7 at 17:37
  • I don't think there's enough evidence to conclude an old earth or a young earth.
    – jaredad7
    Commented Mar 10 at 18:42

My earlier answer was deleted even though it is expressly a YEC answer. Bolded for clarity because a moderator overlooked this fact and I can't undelete.

How do Young Earth Creationists go about showing that this attempt isn't successful?

Because the doctrine of ex nihilo is false.

Interestingly both the current mainstream Christian argument and the secular pseudo-science that evolved from it claim that matter poofed out of nothing, the only difference being that mainstream Christians say it was God who spoke the universe into being, while secularists say it was some physically impossible "singularity" or something like that. Both are incorrect.

The materials of which our bodies are made are in fact very old. It is literally true that we are made from stardust. This does not make atheists like Carl Sagan right.

The age of the universe is in fact infinite. But no one can falsify that this Earth was formed from those materials around 6000 years ago. The Earth is quite young. This is simply using the correct definition of the word "create".

This makes the theology of the Church of Jesus Christ of Latter-day Saints the only one that is compatible with known conservation laws of physics. It is the only belief system that affirms conservation laws even when we include what people call "science" and "physics" (because many "scientists" will tell you to your face that "the laws of physics cease to apply" in the purported big bang, which is a disingenuous argument). Ex nihilo theories presuppose conservation (and the laws of physics generally) to be false. But there is no evidence for such an opinion anywhere. It is just a made-up idea. Language itself does not admit any such thing as "ex nihilo creation".

My take on the subject is my own, but the very meaning of the Hebrew word bara' used in Genesis 1:1 already proves that ex nihilo always was a false doctrine. Every argument to the contrary requires special pleading.

Therefore in answer to the question, How old is the universe, or the matter in the universe?:

The answer is 'infinite'.

The Bible gives us an idea of when this Earth was formed, but it does not say when the stars and other worlds were made. It only says "God made the stars also". Of course He did! Once we take the Scriptures and the known meanings of words to be true, we can dispense with the debate and strife on the subject.

We can then ask a more intelligent question: When was the Earth organized into a globe orbiting the Sun?

Since modern theories don't even allow the Earth to exist, the question of when the Earth was organized is up for grabs. Two hundred years from now someone discovering the ruins of our civilization might find some few articles in an excellent state of preservation. The question of when they were made in part begs the question of how they were made. One must actually have a model for how a thing is made, what it is made of and how it ages in a natural lifecycle in order to begin to estimate its age from its present appearance and condition. Which of us were there when this Earth was formed? Have we witnessed even one complete lifecycle of a planet like our own to use as a model for the age of our own? Until secular "scientists" have an actual, plausible model for how the Earth was formed, they will have to punt on this question. In fact the video documentary link above highlights dozens of evidences that the Solar System is much, much, much younger than modern scholars say it is.

Even if one has a model for how a thing is made and how it normally ages, there is still no such thing (short of a manufacturer's label) as an infallible way to tell how old a manufactured article is in general. If you have a hubcap made twenty years ago, can you reliably differentiate it from one made last Thursday?

This Earth bears its manufacturer's label in Genesis chapter 1.

The Creation is ongoing. My physical body has the appearance of being young because it is young. The materials it is made of are ancient; the matter it is composed of has always existed. Fossils having some extraordinary age is an illusion; the only reason why many think they must be terribly old is because Darwinian textbooks say they are, while ignoring the vastly more credible hypothesis that there was in fact a global Flood.

So everything materially is old eternally, and yet part of it may be newly organized (literally, "created" into something, of things which are not seen as Paul states, speaking of the Creation) as of last Thursday or 6000 years ago and this violates nothing but some people's preconceptions.

if the world was created 6,000 years ago

I have every reason to believe that it was.

I believe this Earth was formed about 6000 years ago as the Bible states, not millions or billions of years ago.

  • To the mods, if you do not understand how a belief system that does not accept ex nihilo can posit a young Earth, please read more carefully and ask clarifying questions rather than downvoting or deleting.
    – pygosceles
    Commented Mar 7 at 17:18

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