You know - the idea that the universe could have been brought into existence instantaneously as a complete thing last Thursday (and thus all of your memories from before this point are merely a clever construct).
An interesting philosophical exercise, I’m sure, but does anyone really believe it? if so, will you still believe it next Thursday?
Of course, but I only believe it on alternate Wednesdays.
Since there are people who believe there are little cities on the moon that NASA is covering up, we can probably find someone who actually ascribes to Last-Thursdayism.
I believe all our brains are in vats.
Certainly some people believe it, at least for a while.
Don’t you recall when people told you earnestly about Crystals or Pyramid Power? The actually got into it, on the premise that “Science can’t describe everything, thus nothing is certain”. The Cartesian dilemma for lowbrows.
They have no trouble believing the earth was formed 4,000 years ago.
I have heard Christian creationists say that they believe in something that amounts to Last-Thursdayism, if not literally the same at least they are in the same philosophical vein. Their argument says that the light from stars was created in transit, even light from stars that would have never existed in the first place if the universe was younger than 6,000 years (like supernova millions of lightyears away that we just are beginning to see now). Fossils created in ground, tree created with rings ect.
The justification for this is that the universe was created to be mature, just like Adam and Eve were created as adults. Of course, the only way they can judge maturity of the universe is to look at the universe now and judge it to be mature.
There was a glitch in the Universe’s creation. I was provided with vivid memories of my life right up until “last night,” when I was provided with the memory of walking into a bar.
Then, nothing until this morning. Ergo, the actual creation was last night shortly after 10:00 pm and took approximately seven hours.
QED
When I was a little kid I used to try to convince myself of it, just to freak myself out.
I’ve never seen anyone claim to actually believe it. I’ve only seen it as a reductio ad adsurdum argument against omphalos creationism.
And, thank you, dear sir, for giving me the opportunity to use “omphalos” in a sentence! Love that word! OOOoooomphalos! “He really puts the ‘oomph’ in ‘omphalos’!” Hey, baby, wanna see my omphalos?
Er. Sorry. Right then. On with the debate.
Actually, the only person created last Thursday is me. You don’t exist. And I’m not writing this post, I’m only dreaming it.
Don’t worry about it manny, you were REAL good. 
and thanks for the sapphire necklace!
jarbaby
So the universe wasn’t created last night, I just saw God?
Whew, that’s a relief. I thought the universe had it in for me, creating itself with all those bills for me to pay.
Last-Thursdayism is the underlying tenant of the “moon-walk didn’t occur” and “the Persian Gulf War was staged on a sound-stage in Burbank” -type conspiracy theories. If it didn’t happen in front of me, it didn’t happen.
Admittedly, it is tempting. I really didn’t believe in the existence of L.A. until 1998, when I visited. I mean, could something that bizarre really exist?
Sua
Hey now, what have I missed in this Last Thursdayism? Sounds like something as relevant and fun as the Flat Earth Society.
Anyone have a link so that I may become more informed on the theater of the absurd?
Last Thursdayism is weak and underpowered. I believe in Last Quantum Microinterval. Since quantum fluctuations go on all the time in vacuum, it is exceedingly improbable, but not a zero chance, that something like an apple will suddenly appear out of nothing. It is even more improbable that it won’t then immediately dissolve back into quantum foam before stabilizing out of virtual-particle land.
But over a long enough timespan, even extremely minute non-zero probabilities can occur. Even, say, an entire Universe randomly popping up out of vacuum, with light in transit, stars chugging away, planets in their orbital geodesics, and so forth.
But even that’s a weak and underpowered outlook. Now say that universe blips, then dissolves back into quantum vacuum. Enormous amounts of time will pass on before another one does, and then another, but they’re likely to be radically different than the previous ones; no continuity of consciousness would be possible. Eventually, over a truly staggering length of time, another universe will pop up that was like one of the previous ones, only different in tiny tiny details–photons have “moved” a smidgeon and whatnot. Picture frames on a film strip, only they’re separated by several billion miles of blank strip between each one–but if a projector is made that blips through those blank strips faster than can be perceived–since only the universe-frames are–their length doesn’t matter, and a continuity of motion and existence is perceived.
Well all right, I don’t actually believe that. But by gob, if you’re going to believe in something like Last Thursday, too much is always better than not enough!
I don’t think anyone seriously believes it, but the rational man has to recognize its possibility.
Actually, a game I play sometimes is to just sit there and observe my own consciousness – you know, just be aware of your thinking. Then wait a few seconds. You remember that a few seconds before you were aware of yourself existing in that moment, which proves that the universe existed back then. EXCEPT, you can’t be 100% sure that that is not an implanted memory. So while you’re doing it, you know the universe exists, but once you get past it, you can’t be sure if you actually did it or not.
Anyway, I think it’s fun.
–Cliffy
OK, seriously. There are lots of creationists who purport to believe that the earth is really 6000 years old, but that God created it to LOOK older. Light from distant galaxies created on the way to the earth, Adam and Eve with navels, the first Bristecone pine created with thousands of years worth of tree rings, geological strata arranged just so, fossils lovingly created in situ.
Of course, God is God, and he can do whatever he wants. If he wants to create a universe that appears to be billions of years old but is really 6000 years old there’s nothing stopping him.
One cannot argue against this idea by using evidence, since the evidence is whatever God says it is. It can only be refuted metaphysically, by pointing out that God can create the world this way any time he likes. He could have created it last Thursday and only made it LOOK like it existed before then. If one accepts the postulate of an omnipotent God that is in the habit of creating misleading universes, then Last Thursdayism makes just as much sense as Young (but old looking) Earth Creationism.
Since Last Thursdayism is obviously very hard to believe, Young (but old looking) Earth Creationism is similarly hard to believe.
Shirley Ujest wrote:
The Flat Earth Society doesn’t go nearly far enough in its Biblical literalism. You should immediately rush right out and join The International Square Earth Society if you want to uncover THE TRUTH![sup]TM[/sup]
I’m going to go with the answer: “Everyone believes this. It just depends on your definition of belief.”
This seems to me to be one variation of a class of paradoxes that I read about in a Martin Gardner book a long time ago. He frames it this way:
We define the color “grue” to be green before the year 2010 and blue thereafter. I tell you that a particular object “X” is green. Every bit of evidence that we can gather about X goes equally to support the theory that
a) X is green, and
b) X is grue.
I forget what explainaition he gives in the book (anyone else remember?) but here’s my take:
It’s a frame of reference thing. Right now you probably believe that you are standing still. But to someone sitting on a train going past you, you appear to be moving while they stand still. This is one aspect of Einstein’s theory of relativity. I propose that “Last Thursdayism” is the same deal. As far as I can tell, Last Thursdayism violates no known laws of nature (in fact some laws seem to hint at a deeper relevance for it as Drastic points out) and leads to no new predictions. There’s absolutely no distinction between Last Thursdayism and consensus reality. Just like there’s no difference between sitting still and moving at a constant velocity. Therefore, to say that you believe in one (Last Thursdayism or consensus reality) directly implies that you believe in the other. It’s simply a matter of perspective.
I could never get the hang of Thursdays.
It has also been said that no one actually believes in solipsism, but that doesn’t philosophically matter as the idea must still be contended with.
Myself, I take a bit more serious view of Drastic’s post (when I’m not busy solving the problem of ubiquitous happiness for a single Consciousness or rambling on about how Eris’s existence is proven by the 2nd Law of Thermodynamics and the HUP; that is, when I’m not busy believing something else) that our universe is a quantum fluctuation which only exists because an interaction occurred which forced the universe into solid exsitence.
Indeed, did the neutron exist before we observed it? Did quasars exist before we looked for them? That is, did the act of observing (hint: not necessarily by a conscious observer) force the waveform to collapse when previously there was no need for the universe to behave one way or the other? Did we create the big bang? Did we create ourselves?
I say: yes. Science can never be complete because nothing exists until we look for it; we aren’t proving scientific theories (theorems) we’re discovering new axioms which didn’t exist beforehand. A direct consequence of the HUP.
Signed,
A Quantum Mystic
Sex, sex, sex, is that all you ever think of?