What is the so-called "Inductive Fallacy"?

This phrase, “inductive fallacy” has been used a couple of times (at least) in discussions on this board. Some clarification will help me. I am familiar with induction as it is discussed in philosophical contexts. I am also familiar with the so-called “problem of the justification of induction”. But the phrase “inductive fallacy” is a new one to me, and it seems to be used on this board in different ways.

Does one commit the inductive fallacy whenever one uses inductive reasoning?

I reach into a sock drawer and pull out, one at a time, 47 blacks socks. I infer that probably the next sock I pull out will be black. Have I committed the inductive fallacy here? If so, what exactly is the fallacy?

Or does one commit the inductive fallacy when one tries to defend inductive reasoning by saying that it has worked in the past, so it will probabl work now? In this case the defence appears to be question-begging, and hence, fallacious.

Or is it something altogether different?


Good question. Clearly, once you allow the legitimacy of induction (inference from the known to the unknown) the first (sock example) is not a fallacy. It is clearly a legitimate case of inductive inference.

I suppose that the the second, taking off from first Hume, and then Popper and his followers, is what is meant. I guess that it was Hume who argued that the defence you cite is question-begging. That is not clear. There have been, as you know, many discussions about all of this. An excellent, although little known discussion of this matter is, “The Rationality of Induction” by D.C. Stove. It is worth reading.
Stove was an admirer of Donald Williams, and you might be interested in the following:

And this general page about David Stove might also interest you.

As you can see, I am a Stove fan, and I like to promulgate his work wherever I can.

this thread covers most of it

ilovephilosophy.com/phpbb/vi … 90&start=0


To Imp - that thread is very interesting, although we’ve been over it a great many times before.

To assert that the future will resemble the past (or the present, for that matter) is illogical, but it is possible that the future will resemble the past.

yes, we have :slight_smile:

true it is possible, but it is possible that the tooth fairy will suddenly appear and pelt everyone with denture tablets…

ever hear tennessee tuxedo? “it’s possible, it’s possible…”


actually when I previously referred the inductive fallcy I actually misused the term, I apologize.

I should have said it was guilty of inductive reasoning.

The inductive fallacy is actually more specific i.e. a very illogical inductive leap i.e. Descartes Method of Clear and Distinct Ideas.

Or for the nanotechnology to change the whole universe into grey goo, as the future King Charles III of England once claimed. Although there’s no guarantee England will still exist at 4 o clock this afternoon…

This is a living nightmare, I can’t say anything

If to infer from the premise that all the ravens we have ever seen have been black, to the conclusion that all ravens are black is to be guilty of inductive reasoning, then I plead guilty. Deductive reasoning is (supposedly) infallible: inductive reasoning is fallible. So, I guess I am guilty of fallible reasoning. So what? Is fallible reasoning necessarily fallacious? Why?

Echoing, to some extent, the question(s) posed by Kennethamy, just what is it that is wrong with inductive reasoning? And/or what is it that Hume is supposed to have shown about inductive reasoning?


There are a lot of things going on here.
There is Hume and his demonstration that induction is circular: The only reason we think the future will be like the past is that past futures were like past past. (I think Russle put it in this formulation, and induction is more general than that, but its a good example.)

Then there is Goodman’s new riddle of induction. That is to say that what we induce is relative to the predicates we use. And by changeing our terms we can predict anything. For instance I go into your sock bin and pull out 47 nack socks, where 10% of nack socks are black and 90% are green. A therefore predict another nack sock, which I know will probably be green. This example is not the best, look up his article for actuall argument.

Then there are fun things like proveing eletrons are yellow. Look around your room. Your computer is non-yellow and it is a non-eletron. Your wallet is non-yellow and it is a non-eletron. You can find a plethora of non-yellow things, and they will all be non-eletrons. By induction, everything non-yellow is a non-electron. The contra-positive, everything that is an eletron is yellow. Ah, induction at its finest. :stuck_out_tongue:

Finially, there are farily well accepted fallicies that can be stumbled upon during inductive reasoning.

Hasty Generalisation- Makeing claims about all members of a set by looking at the properties of too few or unusual examples.

(You pick all the socks from the left side of the dresser.)

Misuse of principle- Using generalisations about a set to apply to weird examples.

(Most Americans like cars. Omish Bob is American. Omish Bob probably likes cars.)

The list goes on…

Hume did not demonstrate that induction was circular. He tried to demonstrate that any justification of inductive reasoning was circular. A very different matter. Whether he succeeded in doing so is one question. A different question is whether even if he did whether that would show that inductive reasoning is unjustified. And a third question is whether if he could have shown that inductive reasoning was unjustified, that would show it was irrational to reason inductively. A fourth question would be whether the fact that inductive reasoning is fallible would show that it is irrational to reason inductively. And, as you indicate, there are a lot of other questions. But those four issues seem to me enough to get on with.

Let me just add that I think that it would be self-contradictory (or something like it) to hold that inductive reasoning is irrational. It is a necessary truth that inductive reasoning is rational. If, for instance, I reasoned that I would be killed if I jumped from a cliff 200 feet high because objects like me have always been smashed up when they fell from that height, and someone said to me, “You’re being irrational” I would think that either he did not know what the word “rational” meant, or that he was joking.

Well you’re right. Although a with a charitable reading of my post you might have inserted ‘the justification of the basic principle of induction (the principle of uniformity of nature) is circular’ for me.

And I think at this point hume’s objection is trivial next to the larger problems. All human thinking is now considered (post-Kant) to have deep base assumtions. The practice of inductive reasoning being just one kind.

What still naws at be is the sort of unintelligablity of the Principal of Uniformity of nature. What properties to we focus on?

Pill A has consitently cured my headaches 40 times. Hence, Pill A will continue cureing my headaches.

All the different kinds of pills I have taken have lost effectiveness. Hence, Pill A will stop cureing my headaches.

In such a case I can make either prediction, and more trobleing after taking Pill A agian explain what happend regardless of what happend.

One of the problems I see with Hume is that his starting point is that “No general proposition about the world is necessarily true.”

Perhaps I’m wrong, but isn’t that a necessarily true proposition?

Let the deconstruction begin.

Another common problem (besides Goodman’s “grue” problem as lostguy alludes to) that is often quoted is the Raven’s problem.

If I say that “all ravens are black,” then I am also forced to hold that no non-black items are ravens.

So if I bring you a black raven… you’ll say “Good Troy.”

But if I bring you a white sock… you’ll say “Good Troy?”

Both the black raven and the white sock confirm my original hypothesis that all ravens are black.

Another take on that problem is that I can say “all ravens are black,” but we know through logic that we can tack on an or operator with whatever we like behind a given proposition and still preserve truth. So the statement “all ravens are black” has the same truth value as “all ravens are black or the moon is made of blu cheese.” So how does the finding that the moon is not made of blu cheese affect my proposition that “all ravens are black?”

One of the problems I see with Hume is that his starting point is that “No general proposition about the world is necessarily true.”

Perhaps I’m wrong, but isn’t that a necessarily true proposition?


Well, if it is necessarily true, then by S5, it is necessarily, necessarily true. But is it “about the world”?

If A or B, and not-B, then A (by disjunctive syllogism) So, it the world is not made of blue cheese, ravens may still be blaci.

This is the best retort that I could think up of also… it could be that metapropositions are not about the world (because they are about other propositions that are about the world).

I’m not entirely sure if I find this convincing or not…

This is an easy with the example I chose, but if the moon was really made of blu cheese, then it would add confirmation to the hypothesis… which is exactly the problem. The moon being made of blue cheese, clearly, has nothing to do with ravens being black.

I guess that there is an extended sense in which whatever you say is “about the world”. That is why we have language: to talk about what is not language.
On the other hand, we can talk about language, itself, too. If I say that the word “cat” as three letters, I am talking about language. I am no talking about cats. And, inasmuch as the only way we can talk is with language, if we are going to talk about language we need a language to talk about language. We call this language about language the, “metalanguage”. So, just in the sense that language can be thought of apart from the rest of the world, so, the metalanguage is not talking about the world.

Do you mean the “hypothesis” that: Ravens are black or the world is make of blue cheese? Well, if the world were made of blue cheese then, yes, that would conclusively confirm the hypothesis. The hypothesis may seem to you (as to me) odd, just in the way you say: the disjuncts “have nothing to do with each other”. But that is a separate question from taht of whether P > (P v Q). That is a necessary truth.

Since inductive logic does not concern itself with valid inferences but with inferences that are probable only, therefore, in your sock example there is no inductive fallacy. The sock you pull out may be white, but since your reasoning is sound and you correctly inferred your conclusion from the evidence that the next sock will be black, therefore, even though the future might speak of a different answer, your logic is sound and so there is no fallacy. This I know is inductive logic and it is used in Science a lot, if we didn’t have this logic, we would not be able to infer anything even if it may have been right. I think scientists use this reasoning because the chances of making a mistake are very small. I feel that inductive fallacy happens when a person using inductive reasoning to resolve something or arrive at a conclusion doesn’t do his homework well, like there may be hasty generalization, etcetera.

Yes. There are inductive fallacies, like post hoc ergo propter hoc but there is no such thing as “the inductive fallacy”. Inductive inference is fallible, and it is not deductively valid, but that is no reason to call inductive inference fallacious.


Those of you who think there is a problem, just what exactly is it that (you think) Hume has shown? I am also curious as to what people mean when they talk about the “principle of induction”. I am not aware of any such ‘principle’, but that may be my ignorance. I do know that inductive reasoning doesn’t depend on the uniformity of nature in any way. After all, (I think it was Strawson who pointed out that), if some specifiable aspect of nature is not uniform, inductive reasoning will show us that this is so-- “no matter what we predict as the outcome for____, it always comes out some other way”.



If I am understanding this correctly, the inductive fallacy can be linked to “the river that constantly flows, everything is flux” philosophy (forgot who it was). Is this so?

That just because an event happened in the past, by the time we have seen the event the scenario has changed and even the same action may not have the same effect. We assume (in our ignorance) that in the real world nothing has actually changed if we set up a scenario we perceive to be identical to the past scenario (which it isn’t identical).