is the following argument valid (but maybe not sound)?

• 47
saw the following in a Kant book (Henry Allison)....
he said the argument is invalid, but I am pretty sure it is not!

If anything is an appearance it is known mediately,
The individual knows that he (or she) acts non-mediately
Thus, action cannot be an appearance.

as far as i can tell this is a modus tollens argument.
seems perfectly valid. (it does not have the form of a fallacy)

BUT, whether it is SOUND or not is a another issue......
• 3.7k
Trying to parse into sentential logic:

p = "anything is an appearance"
q = "it is known mediately"
r = "he(or she) acts not-mediately"
K(x) = "A person knows that x", where x is a variable.

p -> q
K(r)
Therefore, action cannot be an appearance.

I think Allison might be rendering the argument like that so that it's basically a non-sequiter. We could, however, read more charitably and attempt to render it in a logical form, something like what you suggest. But the natural language makes it difficult to assign the same variables if we're going to use the words exactly as written. I might render P2 as:

Action is known non-mediately.

Then we could render

p = "anything is an appearance"
q = "it is known mediately"

p -> q
~ q
Therefore, ~ p

as you indicate, a modus tollens. Though there's something funny about counting action as an "anything". "Anything" is a remarkably vague category! That might also be what Allison is getting at -- we started with "Anything", and didn't draw out the deduction that "Action" is an anything.
• 47
I think Allison might be rendering the argument like that so that it's basically a non-sequiter

So if we look at the following;

If anything is an appearance it is known mediately,
The individual knows that he (or she) acts non-mediately ("action is known non-mediately")
Thus, action cannot be an appearance.

If p, then q
Not q
Therefore, not p

you said that is a non-sequitur...did you mean appears like a non-sequitur?
my logic is rusty, but a non-sequitur would be, i think, a fallacy of form, and thus invalid.
But I can't see it as being invalid (as a modus tollens it would necessarily be valid)...

so maybe Allison got mixed with validity and soundness?!

Thanks again!
• 3.7k
If p, then q
Not q
Therefore, not p

you said that is a non-sequitur...did you mean appears like a non-sequitur?

Heh sorry. That's the second version I offered, put into plainer language, and I agree that it's in the form of a modus tollens. The first one I offered would be a way of rendering the argument into a non-sequitur.

But there's another complaint you could make that "Anything" is too vague. Sure it includes "Action" but it also includes "A is A", or "Unicorns" or "The present King of France" or "A and not A" (Contradictions are surely a part of the vast set "Anything")
• 47
got ya, yep!

glad to know the way Allison presented is VALID (but unsound, at least for him...because of the vagueness I am still trying to work out if it sound or not...).

yes, I agree....certainly is vague, but also the natural language, for me, appears a bit "clumsy"...
he seems to be writing in a shortened form, too....
for example, that first premise...in light of what you said, he should have stated "if anything that is known it is an appearance (because of x, y, z, etc).... then continue with the rest!

Thanks again!!.
• 15k
There seems to be an equivocation involving knowing action. I know others' actions as appearances, whereas I know my own actions " from the inside" so to speak, in the sense that I feel them.

However, I also know them as appearances to some degree depending on the action: I can see my legs moving when I walk, my hands closing on things when i pick them up and so on. The question could be resolved by reformulating the argument I think:

Anything that is an appearance is known mediately,
Action is known only non-mediately
Therefore, action cannot be an appearance.

This makes it clear that the question is whether action is known only non-mediately, and that would seem to be false, which makes the argument as reformulated valid, but unsound.
• 768
"Anything" is a remarkably vague category! That might also be what Allison is getting at -- we started with "Anything", and didn't draw out the deduction that "Action" is an anything.

The argument could also be read syllogistically, in which case 'anything' makes more sense:

1. All appearances are known mediately
2. No first-person actions are known mediately
3. Therefore, no first-person actions are appearances

Of course this is also valid.

Another way to read the first premise would be via quantification: < $\forall$x(Appearance(x) $\to$ KnownMediately(x)) >.

As Janus alluded to, Allison might be thinking that there is a subtle equivocation on 'known'.
• 3.7k
The argument could also be read syllogistically, in which case 'anything' makes more sense:

All appearances are known mediately
No first-person actions are known mediately
Therefore, no first-person actions are appearances

Of course this is also valid.

True! And that'd be more appropriate for the source material.
• 63
If anything is an appearance it is known mediately,
The individual knows that he (or she) acts non-mediately
Thus, action cannot be an appearance.

This argument isn't technically a modus tollens, but it can definitely be converted into one; in which case, it's most definitely valid; & its rightful conclusion would be: what's not known mediately (which is an "individual's action," in the case of this argument) can't be what's known mediately (which is an "appearance," in this case).

Yet, as to it being sound, I must remain undecided about that until I have a better understanding of how this argument's maker defines its terms.
• 166
If anything is an appearance it is known mediately,

One assumes, through the senses?
The individual knows that he (or she) acts non-mediately

Whoa, back up the wagon, Chester! How do I know that my "action" is not just another appearance known mediately? Are we confusing "action" with "the will to action"?

Thus, action cannot be an appearance.

Non Sequitur.
• 166
By the way, please don't fall into the trap of supposing that Aristotelian logic is a valuable guide to truth in the modern world. By all means study it, if Classicism and Scholasticism are your special areas of interest. But Aristotelian logic in the modern scientific and philosophical world is largely irrelevant. It has long since been superseded by developments in many areas, including set theory, Peano/Dedekind arithmetic, and relational (as opposed to predicate) logic.
• 285
there's something funny about counting action as an "anything". "Anything" is a remarkably vague category!

Indeed. :smile:
• 2k
as far as i can tell this is a modus tollens argument.
seems perfectly valid. (it does not have the form of a fallacy)
Modus tollens logic is of the form "If A, then B. Not A. Therefore, not B."
Let's see ...
"If I dream, it means I am sleeping. I don't dream. Therefore I'm not sleeping."
"If I can write in English, it means I know English. I can't write in English, Therefore I don't know English."
"If it rains, the pavement is wet. It does not rain. Therefore the pavement is not wet."
...
Even a 10 year old can see that these are totally invalid arguments ...

As for Kant's argument, I can't say anything. If it were in English, maybe I could. :grin:
• 1.2k
Modus tollens logic is of the form "If A, then B. Not A. Therefore, not B."
Check again.

If anything is an appearance it is known mediately,
The individual knows that he (or she) acts non-mediately
Thus, action cannot be an appearance. — KantDane21
Valid and sound.
• 2k

Why are you repeating to me the quote what @KantDane21 has written?
Do you think that he has not said it loud enough or that I am hard of hearing? :grin:
• 768

You mixed up the inference of modus tollens with the fallacy of denying the antecedent. Modus tollens denies the consequent, not the antecedent.
• 2k

Maybe I did. Can you also explain to me why? What did I say exactly that is wrong and why?
(I would be obliged. Because rarely people do that!:smile:)
• 768
What did I say exactly that is wrong and why?

You said this, as pointed out:

Modus tollens logic is of the form "If A, then B. Not A. Therefore, not B."

I explained why it is wrong here: . Modus tollens denies the consequent (B), not the antecedent (A).
• 2k
You said this, as ↪L'éléphant pointed out:
Modus tollens logic is of the form "If A, then B. Not A. Therefore, not B."
— Alkis Piskas
I know what I said. I asked what exactly is wrong with that.

Well, I found out what exactly is my mistake. The correct modus tollens scheme is: "If A, then B. Not B. Therefore, not A".
And my examples become:
"If I dream, it means I am sleeping. I'm not sleeping. Therefore I dont dream."
"If I can write in English, it means I know English. I don't know English. Therefore I cannot write in English."
"If it rains, the pavement is wet. The pavement is not wet. Therefore it does not rain."
Which are all valid.

Thank you @Leontiskos and also for your intervention.
• 768
- You're welcome :up:
• 1.2k
• 1.5k
Wouldn't this be more:

For all AP, KM (appearance; known mediately).
AC is not KM (action; known mediately)
Thus, AC is not AP.

Same as:
All men are mortal.
Zeus is not mortal.
Thus, Zeus is not a man.

"If anything is an appearance it is known mediately,
The individual knows that he (or she) acts non-mediately
Thus, action cannot be an appearance."

It's a containment relationship that fails to obtain. Or we can define it through membership. Action is not in the set of "things known mediately," while "all appearances" are members of that set. Thus, on pain of contradiction, action cannot be a member of the set of appearances as this would entail that it is an element in the set of things that are know mediately (which is rejected in P2).

We could thus set this up as a proof by contradiction by assuming our premises and assuming that "action IS appearance." This results in a contradiction where action both is and is not a member of the set of "things known mediately," if it is a member of the set of "all appearances." If it is not a member of S(Appearances) then we have no problems at all, Action is simply not a member of either.

I would question if the premises hold up though. Work on brain injuries would suggest knowledge of actions is known mediately and incompletely, varying with attention, cognitive resources, etc.
• 1.2k
We could thus set this up as a proof by contradiction by assuming our premises and assuming that "action IS appearance." This results in a contradiction where action both is and is not a member of the set of "things known mediately,"
Except that we can't do it that way. Remember the OP's question is "IS it both valid and sound?"
If "action is appearance" (by proof of contradiction) then you're setting up an absurd argument before you could finish. That's why it's important to know that that argument is coming from Kant because 1) external objects can only be known mediately and 2) humans have freedom of the will.

Action is not an external thing -- it's coming from you.

If one is in a coma or has a brain injury that they cannot act based on their will, then they cannot argue that they know they're acting non-mediately.
• 488
Perhaps I should stay away from this. Perhaps other people have recognized what seems to me to be obviously wrong, but I haven't picked it up. So -

If anything is an appearance it is known mediately,
The individual knows that he (or she) acts non-mediately
Thus, action cannot be an appearance.

Surely, "If anything is an appearance it is known mediately," is ambiguous, because "it" might refer a) to the appearance, or b) the object of the appearance (i.e. what the appearance is an appearance of. The appearance is what is introspectively perceived, that is, however the object appears to me is its appearance. I perceive appearance directly (non-mediately) and the object of the appearance indirectly (through the appearance and so mediately). If the statement means a), it is false. If it means b) it is true.

"The individual knows that he (or she) acts non-mediately". This is ambiguous, depending on the description under which the action is identified. a) I know introspectively that I am trying to turn on the light when I press the switch. b) Whether I succeed in pressing the switch or turning on the light, I only know from perceiving the consequences of my attempt. If the statement means a), I know non-mediately. If the statement means b), I know mediately.

So, without clarification of those ambiguities, nothing can be said as to whether the argument is valid or sound.

"Thus, action cannot be an appearance." Every appearance is an appearance of something. The object of an appearance is distinct from its appearance. In that sense, this is analytically true and trivial. However, in a different sense, an action can appear to be something it is not, as when I pretend to do something or mimic someone doing it or when I misunderstand what someone is doing. ("Not waving but drowning").

So, depending on how it is interpreted, the conclusion is trivially true, independently of the premisses, or false.
• 4.3k
Perhaps other people have recognized what seems to me to be obviously wrong, but I haven't picked it up.

Perhaps because the OP stipulates a Kantian source indirectly through Allison, which means it should for all intents and purposes be “picked up” in Kantian terms.

A syllogism suffering premises with no relation to each other, is a paralogism;
The conceptions in the premises of a paralogism determine the subset of it, here it is a transcendental paralogism, that is, a remarkable error in content-kind while its form is unexceptional.
A paralogism is an error in reason, a systemic flaw which manifests when the minor treats of its conceptions differently then does the major, and this is called sophisma figurae dictionis, re: ’s equivocation.
It follows that in any case where the conclusion is true but is not derivable from either of the premises because they do not relate to each other, whether the syllogism is valid/invalid, sound/unsound, is completely irrelevant. The whole thing is just a hot mess, but is usually passed over in the everyday use of reason.

The source in Kant for this, is B411, with the explanation in the footnote at B412. Allison uses a different syllogism, but it contains exactly the same error of equivocation.
• 488

This makes it clear that the question is whether action is known only non-mediately, and that would seem to be false, which makes the argument as reformulated valid, but unsound.

Yes, I see that Janus is chasing the same point about action, and has reformulated the first premiss to avoid the ambiguity of "it".

I didn't understand that this was a Kantian discussion. I don't know enough about those texts to contribute.

Thank you for clarifying.
• 3.7k
To be fair I was just trying to parse the argument as is rather than trying to interpret it in terms of Kant.
• 4.3k
I didn't understand that this was a Kantian discussion.

Ehhhhh…..the discussion begins with, “saw the following in a Kant book”, so makes sense to relate the following to what was actually in the Kant book. Not to mention, what’s wrong with the following, is specified in the Kant book. And from there, the best answer to the query implied in the OP, is given from the Kant book, which is….the stated syllogism is indeed invalid.

There are other ways to prove the error, sure; I just gave the one I knew about.
• 1.5k

Well yeah, that's the whole point of the reductio, but it's generally considered a valid way to form proofs (exceptions like intuitionist mathematics exist of course). I was just showing different ways you could show the same thing, syllogism, containment, or via and proof by contradiction using sets.

It's valid because "action is mediated" is not our argument. Our argument shows that "action is mediated is a contradiction," and then follows "x is a contradiction, contradictions are not true, thus not x."

Although, I am aware that mathematicians generally prefer direct proofs over the reductio, because a reductio lacks fecundity, it cannot be used to set up new proofs as easily.

IMO, the containment relation is the simplist of these and is underappreciated. You can teach proofs like that to a kindergartner, and re the thread on Spencer Brown's Laws of Form, you can do a lot with distinction and containment.
• 488
There are other ways to prove the error, sure; I just gave the one I knew aboutMww

Well, there seems to be a variety ways to prove the error. Something for everyone. Consensus!
• 768
A syllogism suffering premises with no relation to each other, is a paralogismMww

But it is quite odd to claim that the two knowledge-predicates have no relation to each other. Metabasis eis allo genos does preclude a strict demonstration because not all premises apply per se, but it does not preclude a looser and less exact syllogism. I think that's exactly what is happening here. The conclusion, "Therefore, no first-person actions are appearances," is sound vis-a-vis the metabasis. The error or lapse does not preclude a non-demonstrative kind of inference. The genus-predications map to one another in an inexact way, but they are not wholly equivocal. We can quibble about what invalidity means, but I don't think the syllogism is "just a hot mess."

In other words, ' two terms are not strictly equivocal; they are pros hen homonyms.
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