Tag Archives: Reductio ad Absurdum

Project Logicality | Reducing to Absurdity

Screen Shot 2016-04-07 at 21.28.48Here we discuss what is otherwise useful and valid reasoning, known as the Reductio ad Absurdum. In its valid form it may be used to show an argument’s claim to be false by following it to its ultimate logical conclusion, revealing a contradiction, an absurdity, or it may be used as a form of Straw-Man argument, known here as the False Reductio. I’ll deal first with the latter.

This works by forcing a conclusion that while absurd, doesn’t use the actual reasoning of the original argument, such as:

If you’re skeptical of the existence of UFOs, Bigfoot, and ancient aliens, then you must also be skeptical of the existence of the Taj Mahal, the Sydney Opera House, and the Empire State Building, since you’ve never been there to see those places.

This is fallacious because the proportional nature  of the claims requires proportional standards of evidence. The criteria for each differ, and the argument itself ignores the use of evidence other than anecdotal testimony and grainy, low-resolution, or obviously photoshopped videos and photos.

Here is one of my favorites:

If you don’t believe in psychic abilities then you also disbelieve in dark matter and dark energy, so 90% of the Universe does not exist to you because you haven’t seen those either.

Again with ignoring evidence other than personally witnessing something. Also, it fails to consider the fact that though there is some question as to what dark matter and dark energy are, they have been reliably observed by their effects on the visible universe itself, and the evidence shows that they are real. Clearly, elusive supernormal psychic abilities and invisible but indirectly observable astrophysical phenomena are not analogous.

But all is not without a ray of light in the dark. There is an informally valid and intellectually honest use of this as well, to highlight the fallaciousness of some extraordinary claims. Here, the actual train of logic of the original argument is kept intact.

Here are a couple of silly claims I’ve come across:

The ancient Egyptians could not have built the pyramids without alien or Atlantean help. They were far too primitive a civilization.

In order to know what a human skeleton looks like, the Maya and Aztecs must have been given X-ray machines by ancient astronauts.

Such claims reek not only of thinly disguised racism and colonialist arrogance, but stupidity and historical shortsightedness as well.

And skeletons? Come on, that’s just silly!

Here, we may apply the same train of logic to what the proponents of these ideas, mostly whites of Western descent, dare not apply it to: early Europeans:

How could the Medievals possibly have had the intelligence to invent such marvels as the crossbow, stained glass windows, steel armor and weapons, and those massive cathedrals! They had to get their technology from aliens, because they were too inept to come up with them on their own! They must have gotten medical imaging technology from the aliens too, because Medieval art has lots of skeletons in it, and how could they have possibly known what those looked like without using it?

Absurd? Clearly it is, and in retaining as closely as can be the reasoning of the original applied to another subject, it shows that.

A side note: Technology is cumulative, and evolves over time, with earlier, precursor technologies leading to better, more advanced ones, with archaeological remnants to show this progression, no matter the location, or ethnic and cultural makeup of the civilization. This is true even dating as far back as the Paleolithic with stone tools.

Never underestimate human genius. There exists brilliance in every human era, with no need to gift early peoples with technology from super-civilizations for such tasks as constructing even impressive monuments, which require only engineering, tools, and social organization which we know they had, as opposed to the claims of pseudo-historians in massive, and dare I say, monumental, arguments from ignorance.

But I digress.

Reason is a tool. Use it well and it will serve you reliably, leading to the acquisition of more true conclusions than false ones. But abuse it, and the content of the claims you accept and promote becomes much more prone to error. Especially when you misrepresent the chain of another’s reasoning for ideological ends.

Project Logicality: The Reductio Ad Absurdum – Invalid & Valid

Let’s suppose that there are two men engaged in an argument, we’ll call them Mr. A and Mr. B.

They’re engaged in a rather spirited discussion on psi-phenomena, and Mr. A argues that psi is unlikely to exist because truly compelling evidence, in the form of successful replications of psi, regardless of the beliefs or level of enthusiasm of those attempting the replication of the initial studies, does not currently exist.

Note that he is not saying he doesn’t think it’s real because he hasn’t personally experienced it nor seen concrete, direct evidence of its existence, but that despite the immense volume of evidence in the literature, it just isn’t very convincing by reasonable scientific standards, and so one should remain skeptical for the time being.

Nor is he arguing that it’s impossible, only unlikely to exist until convincing evidence under reasonable conditions by reasonably objective research workers indicates otherwise.

In his rebuttal, Mr. B argues that Mr. A, in thinking that psi probably isn’t real, must also believe that dark energy and dark matter must not exist, because Mr. A hasn’t seen them either, and that he must therefore believe that 90% of the universe must not exist.

But wait…

Mr. A said nothing about needing to see psi himself, only that convincing evidence obtained under adequate conditions by non-believers in psi is not there, not yet, saying nothing at all about the evidence needed to establish dark matter or dark energy, both of which have different evidential requirements than psi does, for which almost the entire body of data consists of statistical quirks, convincing or not.

Mr. A’s argument has, as can be seen, been misrepresented, and in such a way as to carry it to an absurd conclusion, the claim that by his own reasoning, most of the universe doesn’t exist.

That last was an example of a fallacious Reductio ad absurdum, and of course there was probably much more said than simply the above. But Mr. B’s argument was fallacious because it led to an absurd conclusion without using the actual chain of reasoning of Mr. A’s argument, by misrepresenting that argument as a straw person.

Later, Mr. A and Mr. B get into a discussion of the nature of reality, in which Mr. B, not liking the direction of the argument, responds to what he feels are the overly absolutist statements of his opponent, in exasperation saying in a rather postmodern fashion, “Reality is nothing!”

There are several ways that this can be interpreted, but in this case, a clarification is not offered, and Mr. A cannot read minds nor thinks at the time to ask for a clarification, so the most likely interpretation, that B is claiming reality doesn’t exist, will have to do.

What does this mean? Can we carry this claim to it’s ultimate conclusion without merely misrepresenting it?

Let’s see…

What is reality? And I don’t mean what is its ultimate nature in fact, but what is the meaning of the word? How is it used?

Reality, by definition, is that which can truly be said to exist, no matter it’s nature or other properties:

a=a: reality is real.

To be real, this quality of existing is essential, whether the thing existing is directly observable or not. If something doesn’t exist, then it’s not part of reality, and if it’s not even imagined, it’s not fantasy either.

What is everything that is real?

We call it the Universe, or the Cosmos, take your pick, though myself, I’m partial to the latter, though for this discussion I’ll use “universe” for the totality of existence.

To say that reality is nothing, in this context implies that the universe doesn’t exist, 100% of it, not just 90% in the straw person argument above, since the universe is everything, with or without any supplementation to it by anything allegedly supernatural.

But if the universe is everything that exists, and everything currently within and originating within the universe, by definition existing as part of its totality, and therefore part of all reality…

Hmmm… I smell something funny about this, don’t you?..

If the ‘reality does not exist’ interpretation holds and the claim were true, then the claim could never be made, since neither of the two persons would even exist themselves in order to have their argument.

But if Mr. B exists to make his argument to Mr. A, and Mr. A exists to hear the argument, then the claim, assuming this interpretation, is simply, obviously, and demonstrably false.

Clearly this is an unacceptable conclusion, at least until such time as Mr. B offers a clarification of his statement that requires a different interpretation of what he said, we must assume what we did know and thus consider this a valid Reductio ad absurdum.

But personal debates among argumentative friends are often messy, impromptu, with little if any ‘rehearsal’ or ‘practice’ beforehand, and unless both are skilled arguers, it is unlikely that normative standards or ideals will reasonably be met without time and practice.

This is just one of the hazards of personal arguments, but it’s something that can be improved if done systematically and with time, skillfully and instinctively, but the rewards of rich and confident testing of our knowledge by argumentation far outstrip any annoyance that may result in the beginning.

Logical Fallacies — Notes on Common Fallacies & the Fallacist’s Fallacy

Identifying and labeling logical fallacies when they are used as argument strategies is useful — It weakens the rhetorical effect of the labeled argument, possibly even disqualifying it as viable support for a position.

But common fallacies can be used not only to legitimately point out truly inductively weak, logically invalid, or otherwise unpersuasive arguments, but may be overextended as well — they may be misapplied to label sound, cogent, and persuasive arguments as fallacies if and when this is not the case.

  • The appeal to authority — This is often used to dismiss a position as merely an argument from authority, if and when it is actually an argument by authority — that the claimed credentials and qualifications of the authority are both true and relevant to the matter discussed, and the authority appealed to has a genuine basis for making their statements.


“Oh, that’s just something that those Establishment archaeologists say to hide the Truth about the Mayan pyramids!”

  • Incorrect cause — This can often be used to deny an actual causative correlation that has been shown real, claiming even then that “correlation is not causation,” and invoking a more complex causative relation than needed when the evidence may well point to the simpler relation that A causes B.


“Actually, the warming of the climate is not caused by human industrial pollution, it’s really just a natural cycle that correlates instead with the warming of Mars…and cow farts!”

  • Ad hominem — This can be used to argue that the critic of an idea is attacking the proponent of an idea rather than the idea itself — note that an insult, by itself, is not an ad hominem. — it only becomes that when the insult is used as a reason that the one insulted is wrong without substantially addressing the argument itself. An ad hominem is not always a fallacy and can also be used in a legitimate way, as in pointing out a real and relevant conflict of interest or bias in the subject.


“You just say that because you’ve closed your mind to the very possibility of the unconventional.”

“I don’t trust anything you say…you’re in the pay of those well-funded liberal environmental lobbyists.”

“Scientists are arrogant for claiming they know anything.”

  • Reductio ad absurdum — Like some other fallacies, this may be used as part of an inductively strong argument or logically valid one and is often used in formal logical proofs. It becomes a fallacy, a false reductio ad absurdum, and a straw man(see below) when used to argue the silliness of a position without using the actual, original line of reasoning in the argument.
  • Straw man — This one is easy to commit, and easy to overextend when applied to a legitimate critique of one’s position using the premises and logic actually involved in the original argument. To avoid this, it is necessary to do whatever is required to understand an opponent’s argument and interpret it as charitably as possible, without over-generously ignoring non sequiturs and inconsistencies, or being too proud to ask for clarifications.

To overplay this fallacy and falsely accuse your opponent of a straw man is to commit one yourself through misunderstanding the counterargument given.

An example of both a false reductio ad absurdum and a common straw man:

“If you don’t believe in psychic powers, then you must also not believe in dark energy and dark matter, so 90% of the universe must not exist, because you haven’t seen those either!”

  • Special pleading — This form of reasoning is not itself innately fallacious, and can be a perfectly good logical strategy for constructing hypotheses for testing. The fallacy comes when it is used to dismiss fair criticism of an idea or used in an ad hoc manner to patch together a set of hypotheses in an overly limited fashion and render them untestable…neither falsifiable nor meaningfully verifiable. It is also over-employed when used to criticize a valid or strong argument as being ad hoc, when in fact the argument’s premises and assumptions are supported through prior evidence, arguments, or observations and the reasoning is not overly baroque in structure.


“Psi is real, and has been successfully replicated, but skeptical readers of journals these studies are published in use an unconscious, retroactive, and unobservable psychokinesis that reaches through time and causes the successful replications to fail.”

“The big bang model of cosmology can’t possibly be viable…it’s got too many patches like fairy-tale dark matter, undetectable dark energy, and imaginary inflation propping it up from falsification by protecting it from the data.”

There is also the Fallacist’s fallacy, which is to argue that because an argument is invalid or weak that the argument’s conclusion must therefore be false.

This shows a misunderstanding of the relationship between the truth value of the conclusion and the nature of validity or strength.

Validity means that if the premises are true then the conclusion must be automatically — There is no valid logical argument in which the premises can be true and the conclusion false, because the chain of reasoning follows with certainty, but it is possible for an argument to be fallacious and still have a true conclusion — it just doesn’t follow from the reasoning, requiring a better argument for one’s position.

The same applies to inductive arguments without the deductive certainty.

A conclusion can be false, even with true premises, and an argument therefore not follow, but not following from the premises does not imply the falsehood of the conclusion, only that the argument itself is not cogent, is unpersuasive, and cannot be used to support that position.

Arguments BTW, cannot themselves be true or false, only the individual statements making them up.

Logical Fallacies — Begging the Question & Other Fun Forms of Specious Reasoning

Specious reasoning...  ...I callz u on it!

This post deals with several forms of invalid reasoning, and the first of these is Begging the Question, additionally known as Assuming the Answer, a form of circular reasoning.

As an informal argument, this is borrows from the form of a tautological argument, and a common fallacy, in particular involving factual, definitional, value, or policy claims or arguments which the conclusion of the argument, is one of its own premises, or reasons given to support it.

With this fallacy, specious in claims of fact rather than its use in pure mathematics or strict symbolic logic, where this form of argumentation can be valid if sterile, the premise assumes the conclusion’s proof as a given when this is the very thing that has to be demonstrated, especially in those arguments where the conclusion is in some way controversial or otherwise uncertain.

  • I’ve heard that this house is haunted, and I saw a ghost last week when I was drifting off to sleep, so this house must be really haunted.
  • Psi abilities are defined as a significant deviation from the laws of chance, so any significant deviation from the laws of chance must mean that psi abilities are operating.
  • The uncanny precision of the fine-tuning of universal constants that allow life to exist requires the work of an intelligent agency to perform the fine-tuning, therefore an intelligent agency fine-tuned the universe.
  • My gods speak directly to me when I read Their holy Word, since Their holy Word states that They speak directly to me when I read it.
  • Of course Cthulhu will eat his brain if he reads that dangerous book, because if it wasn’t dangerous, Cthulhu wouldn’t eat his brain for reading it!

Employment of the phrase ‘begging the question’ in ordinary language isn’t a fallacy as long as no argument is being made, in the usage of ‘questions that beg for answers.’

Next in line we have…

…The Straw Man Argument:

This is a frequently encountered and generally rude flaw in arguments, from discussions to formal debates, though more conducive to annoying and heated quarrels than constructive dialogue, a common fallacy, and well-known as a red-herring strategy.

It’s use is most often appreciated by those who intentionally employ it, for this fallacy is incredibly easy to execute.

A quick and easy way to make it look like one won a debate is to deliberately misrepresent one’s opponent’s position, especially by distorting it to make it look ridiculous or weak and easily refuted to the target audience.

Once this is done, the user can argue against the misrepresented position and claim that the opponent’s actual argument has been summarily dispatched.

A Straw Man argument is an informal fallacy and its use is intended to avoid or distract from the real argument instead of actually addressing the position an opponent is actually taking, and for this reason is always a logically unsound, and often intentionally dishonest form of argument.

Included in this fallacy are such tactics as intentionally misdefining words, such as the following:

  • “Global Warming is a religion, and policies concerning it shouldn’t be undertaken by the Federal government…”
  • Misdefining ‘Gravity’ and ‘theory’ and ‘fact’ to declare that “Gravity is not a fact, just a theory,”
  • Putting words into one’s opponent’s mouth…
  • …and that all-time favorite of ideological apologists of all mutant strains, quoting one’s opponent out of context, even completely fabricating a quote, which becomes an Argument from Quotation.

Straw man arguments are often committed, not intentionally, but out of a genuine misunderstanding of an opponent’s position, so it is important to actually understand your opponent’s arguments before offering your rebuttal.

Believing that you understand an opponent’s position when in fact you do not is what psychologist Ray Hyman refers to as a Type III cognitive error. Needless to say, this is something to be avoided.

A few more examples of this fallacy are below:

  • If humans came from apes, then why are there still apes? (The question is a lot like “If children come from adults, why are there still adults?”)
  • “Evolution teaches that energy, such as heat or light, plus matter, eventually becomes new life.”
  • Mainstream cosmologists ignore any evidence that doesn’t fit their preconceived beliefs and deny that there is an electromagnetic causation for anything in space.
  • If you don’t think that psychic phenomena are real, then you must also disbelieve in dark matter and dark energy, because you haven’t seen those either, and therefore you deny that 90% of the universe exists!

That last is an example of a Reductio Ad Absurdum as well…

This fallacy probably takes its name from the idea of two individuals being at odds with one another, whereupon one builds a straw effigy of his foe, and destroying it, claims to have vanquished his actual opponent…

…but sources vary, and another probable origin for the term is the use of straw target dummies used by some military training camps for bayonet and combat knife practice by recruits, effigies that crudely simulate a live but immobile opponent for the purpose of repeated poking with sharp objects and other pointy things.

It is a straw man argument to claim that one’s opponent is committing a straw man, when the opponent is actually making a counterargument which deals with one’s argument using the definitions established from the beginning and in its true context.

And then there is…

…Shifting the Burden of Proof:

This is one of the more common intellectual strategies of anti-science contrarians, also called the Negative Proof Fallacy.

The intent is to attempt to shift the burden of proof for a claim away from oneself, and onto the critics, arguing that said critics must prove that the pet claim in question isn’t true, or to demand proof to an impossible standard of evidence that a widely accepted and otherwise well-supported theory is true. This last use is also a Moving Goalpost fallacy.

This is a fallacy because of a principle in science known as the Null Hypothesis, which demands that the burden of proof falls upon the party making a claim of fact that has yet to be established, not the claim’s critics.

Simply put, it demands that ‘Any new idea is to be considered probably untrue until it is tested and demonstrated true beyond the doubt of a reasonable person exercising critical judgment.’

This applies to all new theories, and any theory passing this gauntlet will become accepted by the scientific community at large, despite what you may hear from cranks. Any theory not passing this requirement is then relegated to the intellectual garbage heap of failed ideas.

Also, It is simply not possible to prove a universal negative, to prove absolutely that a claim of fact isn’t true with a finite data set. It may be possible to move the probability of something being true ever closer to zero, but you can never actually reach that with a finite amount of even negative evidence.

Nor is it possible to prove anything absolutely true, to a probability of exactly one excepting those singular documented events that have already happened, like life arising and evolving on Earth the way it has.

Repeatable phenomena can only be demonstrated beyond a rational doubt, which is really all that is needed in science.

Unfortunately, not everyone’s doubt is rational, thus leading to the commission of this fallacy by proponents of pseudoscience, who insist that critics explain away all of the data, to their satisfaction or demand that the critics explain absolutely any perceived ‘anomaly’ in a standard theory, such as evolution, relativity, quantum mechanics or such, again to a standard of satisfaction that cannot be met, arguing that if it is not, that the standard theory is ‘in crisis’ or ‘on shaky ground.’

It’s just a rhetorical stunt, and any attempt to thus improperly shift the burden of proof in these ways should simply be met with a refusal to comply with this intellectually dishonest tactic, and a firm reminder of on who the burden actually rests. It’s most often used when the proponent of a theory has no real positive evidence in favor of his own idea, which is usually the case in pseudoscience.

And finally…

…The Tu Quoque Argument:

Tu Quoque is a Latin term, and in English it means “you as well.” It is a subset of ad hominem in which one attempts to justify wrong doing by arguing that one’s opponent commits the same, that one’s opponent is no better. This is a way of cheaply dismissing an argument without actually addressing it, as per a normal ad hominem, by attacking the one argued with rather than the argument. A few examples are provided below:

Why should I accept your contention that global warming is real, and at least partly caused by human beings, when you drive a gas-guzzling SUV of the same make and model as mine? Your argument is bogus!

or another…

I do not feel compelled to hold free elections in this country to restore peace when your followers in the opposition party commit just as much violence against my militia and others of my own tribe as you claim mine do!

and a third comes to mind…

Your argument that the evidence for psi is not sufficiently robust to establish it’s reality carries no weight when your organization launches scathing personal attacks against my institute’s staff in response to our criticism of your blind materialistic ideology.

Needless to say, I find it amusing to go on forums and skim over the threads for these and other fallacies. It’s even fun to pick out and identify new ones, or new variations of familiar ones, and just as fun to construct counter-arguments for the examples you see there.

While you probably won’t spontaneously develop pointed ears, arched eyebrows or a black goatee, familiarizing yourself with invalid reasoning can make it easier to identify it in one’s own argument even without being a member of the Evil Spock school of logic.

Have fun.

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Logical Fallacies — the Reductio ad Absurdum

Hey, guys. This entry deals with a fallacious use of an otherwise perfectly decent bit of reasoning, known as the Reductio ad Absurdum, or ‘reduction to the absurd’ argument.

In its valid form it may be used to show an argument’s conclusion to be false in following it to its ultimate logical implication, and showing that to be well, absurd, or it may be used as a form of Straw-Man argument: this is also called the False Reductio ad Absurdum. I’ll deal first with the latter.

This is committed by misrepresenting and forcing a conclusion that while absurd, doesn’t use the actual train of reasoning of the original argument, such as the claim that if one is skeptical about the existence of cryptozoological creatures, one must also be skeptical of existence of the Empire State Building, since one has not witnessed that personally either.

It’s a fallacy because the requirements for evidence of the two are not the same. This particular example ignores forms of evidence other than eyewitness testimony and also the use of logical inference .

One of my personal favorites of this is the claim that because I am skeptical of psychic abilities I must therefore also be skeptical of dark matter and dark energy, and must therefore believe that, and I quote, “90% of the Universe must not exist because I haven’t seen those either.”

This ignores the fact that though there is some question as to what dark matter and dark energy are, they have been reliably observed through their effects on the visible portions of the universe around them, and the evidence shows that they are real to a high degree of probability, pending further and better evidence.

More and better observations in the future may invalidate current evidence of their existence, but for now they are useful ideas, even if they turn out to be incorrect at some later time.

Clearly, unobservable Psi phenomena and directly invisible but otherwise observable astrophysical phenomena are not analogous.

There are valid uses of this line of argument as well, when the actual train of logic is retained without misrepresentation. Some of the claims of pseudohistory, for example, such as that the ancient Egyptians could not have built the pyramids without alien help, or that in order to know what a human skeleton looks like, they must have been given X-ray technology from ancient astronauts. Arrgh! this necessitates the use of a suitable image from my media library….

Aiee! *Ahem*… Anyhoo, this line of thinking can be demonstrated as ridiculous by applying the same train of logic to what the proponents of these ideas, mostly whites of European descent, dare not apply it to: medieval white Europeans, as follows:

  • How could the Medievals possibly have had the intelligence and imagination to invent such marvels of technology as the crossbow, stained glass windows, steel armor and weapons, and those massive cathedrals! They must have gotten their technology from aliens, because they were obviously too inept to come up with them on their own! And what’s up with all those religious apparitions during the Middle Ages?? Misinterpretations of alien astronauts, of course!! They must also have gotten medical imaging technology from the aliens too, because Medieval art has lots of skeletons in it, and how could those stupid, credulous Europeans have possibly known what those looked like without it?

Without belaboring the point, I think you get the idea.

This is generally a valid line of argument in formal logic and often used in mathematical proofs. When it is used in a specious manner, however, this is generally because of distortions in the argument’s logical structure or problematic assumptions in the misrepresented argument.

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