You can't show that inductive reasoning is unjustified

[brain in a vat]

You can't use deduction to prove that "all inductive inferences are unjustified". And if you use induction your argument is self-defeating.

[The Voice of Time]

To the text: No, but you could, hypothetically speaking, prove that some deductive inferences are wrong x)

To the thread-title: You can show that inductive reasoning is unjustified by deducing from it a paradox that can't be solved in favour of the previously undertaken inductive reasoning. You can also do so by making a paradoxical counter-induction.

For instance: I see a red apple, this means all apples are red.

Counter-Induction: I see a green apple, this means that all apples are green.

Normally this would lead to a synthesis, but if you are unwilling to give up on the first induction you'll not get that synthesis, so you first have to conclude it is "unjustified", although it could've been justified "at the time", unless of course one adheres to a principle of letting time tell, which can be important in cases of seriousness, like crime.

[brain in a vat]

Sorry I just edit my post to correct my typing error. (see bold) You can't use deduction to prove that "all inductive inferences are unjustified". And if you use induction your argument is self-defeating.

[MGL]

You can't use deduction to prove that "all inductive inferences are unjustified". And if you use induction your argument is self-defeating

You could if you could demonstrate that it was a tautology, such that it was logically impossible that an inductive inference is justified.

For instance, consider the following reasonable presumptions about justification:

1) An inductive inferences of the form "All x's are y" is justified by instances of x which are Y
2) Instances that justify "All x's are y" must be restricted to cases of x which are y. No other state of affairs should count as justifying the inference.
3) Anything that that justifies an inference justifies its logical equivalent.
4) A logical equivalent of "All x's are y" is "All non-y's are non x's"
5) The claim "All non-y's are non x's" is justified by instances of non-y's that are non-x's.
Therefore:
6) Instance of non-y's that are non-x's justify the inference "All x's are y"


BUT 2) contradicts 6). Therefore, if all the above presumptions hold, we have to conclude that such inductive inferences cannot be justified. And if there are no other kind of inductive inferences, then the statement "all inductive inferences are unjustified" is proved.

[Hobbes' Choice]

You can't use deduction to prove that "all inductive inferences are unjustified". And if you use induction your argument is self-defeating.

Are you implying that you can use deduction to prove that SOME inductive inferences are justified?

If you use "induction in you argument' then you would not be using "deduction", which makes your second sentence irrelevant and a non-sequitur to the first sentence.

So why are you making this statement?

[Hobbes' Choice]

Sorry I just edit my post to correct my typing error. (see bold) You can't use deduction to prove that "all inductive inferences are unjustified". And if you use induction your argument is self-defeating.

This seems to be exactly the same as post one?!?!?1