Tyler ’s Comments (group member since May 09, 2008)

Tyler ’s comments from the Philosophy group.

Hi Jenny --

Welcome to the group. The question of what art is doesn't have a thread here yet, but I expect many people are interested in it.

I've read some philosophy from Late Antiquity, Early Medieval Philosophy (480-1150), by John Marenbon, but I have yet to read his companion book about medieval philosophy itself.

I hope you will enjoy the discussion threads already in progress, and if you don't see one about a topic you're interested in, by all means start a thread on it, too.

Hi Bobbi --

You're posing two questions. To your last questions I have to ask again why you'd hold that scenario open as a logical possibility in contrast to our daily experience.

To the first question I'd say that the first act of free will is the decision to focus your attention in one direction and not another. Animals don't have that capability as far as I know, and the first humans to achieve it began thinking in a recognizably human way. The loss of this ability, such as happens in dementia, would mean you no longer have free will.

Hi Bobbi --

If we had reason to doubt reality or our awareness of it we might think of free will as an illusion, but there would then be no existential basis for the doubt. An agent having independent access to reality might know if we're dreaming, but the agent himself couldn't be sure he wasn't dreaming. What we're left with is a regress of doubts which by itself warns of a flaw in such reasoning.

In everyday life we would never doubt that we were awake except in odd circumstances. The idea of an illusion can be held open as a logical possibility, but an endless array of thought experiments are logically possible and it would be necessary to state why that possibility is being kept open.

Hi Mike --

I question whether determinism and free will are actually incompatible, so An Essay on Free Will sounds like an interesting rejoinder to that.

I think free will is the case if a person's decision could have been other than what he actually chose, so that would be my working definition.

One factor in the free will debate is the nature of consciousness. I think it is non-material, and as a result it will be difficult, if not impossible, to explain it in scientific terms. I'm persuaded by Sartre's description of it in Being and Nothingness, which argues that free will is essential to any workable explanation of human consciousness.

Hi Tim --

I find it an interesting coincidence that Heidegger would be developing his thoughts on “Being and Time” so soon after Einstein’s work on the space/time continuum. Is there any connection here?

Spatiotemporal phenomena were taken up by Kant, and I suspect that Kant was thinking about Newton when he gave them such a prominent treatment.

Einstein, of course, would have underscored the importance of these dimensions. But because Heidegger was a philosopher first, I think he had Kant in mind. If P.D.'s interpretation is on target the question of reidentification -- how a person comes to be over time -- was a concern of both philosophers.

We tend to think we deserve the good outcomes in our lives and don't deserve the bad. In its everyday use people often misapply the term deserve by not adequately accounting for external factors that enhance or restrict freedom of action.

Hi Zoot --

The article on indicative conditionals leads back to relevance logic. Somewhere, there was a reference to Ackermann which I can’t now locate, but which said he was trying to strengthen inferences so as to exlude irrelevance. That's what I had in mind, but I haven’t seen why an entirely new logic has to be constructed to do that.

All in all, however, it’s my point about necessity/entailment/etc. Whatever has happened, modern elementary logic construes necessity that way. And if it has to do with ordinary language or relevance logic, so be it as well. The discussion of classical logic and material implication is interesting, but I think it also adds a layer of confusion.


What people? Used what? What are you talking about? You mean the people who used the word 'therefore'? /// I don't know the details - I don't actually know anyone who would assert that all lemons wear raincoats or that the moon is made of cheese.

I mean people who actually use or study classical logic, paradoxes and all. I was wondering what they would have said relevantly connected premises and conclusions. As you pointed out, necessity/entailment/etc. is not easy to pin down, so the answer may simply be the truth of the premises alone, as little sense as that would make in a more rigorous logic. Still, that's what was bothering me.


You seem to think that 'necessity' has something to do with which propositions we use, so that […] 'necessity' is somehow lost because of the lack of relevance between the two propositions in conditional. But in classical logic, 'necessity', in the sense you seem to be using it, has nothing to do with that. Whether a conclusion necessarily follows from the premises depends on the logical form of the argument

And in relevance logic, would necessity also apply to the form only?


You question whether material implication alone can be the basis for calling a logic deductive? I'd question that too. Good thing I've never said anything remotely like that. Some deductive logics contain material implication, some do not.

Excellent. We’re in agreement, then. Yes, I realize you weren’t advocating that personally. The discussion of material implication is really interesting, but untangling it may have sidetracked the discussion a bit.


…you can replace "p" and "q" with whatever the hell you want; "q" still necessarily follows from those premises.

Yes, but I’m not trying to dig in my heels against variable forms as the basis of necessity in classical logic. Rather, I've been trying to get a handle on the specific kind of necessity/entailment/etc. that classical logic uses.


That doesn't make much sense to me. It refers to a property of a logic without reference to a logic?

No, that was hastily worded. I mean the book develops deductive logic, but it doesn’t specify a particular system such as classical, relevant, etc. It really doesn't take up material implication as a discrete subject either, at least not the way the Wikipedia page does.


Yes, but one of the conditions you have for 'necessity' (and for 'follows from', etc) is that the premises and conclusions be relevant to each other.

I see what you're saying, but “relevance,” to me, implies something just short of necessity.

Hi Zoot --


The person asserting it is inferring from 'all lemons wear raincoats' to 'the moon is made of cheese'. You don't have to consider it a valid inference, or a correct inference, or a coherent inference, or whatever, but it's still an inference.

How? From the truth of the premise alone? That seems to be the rule, but there’s no logical necessity to the material implication.

I'm emphasizing material implication 'to the exclusion of logical necessity'? What are you talking about there? You keep bringing up 'necessity', and maybe you should explain exactly what you mean by that.

All your examples of material implication are devoid of necessity. What I mean by necessity is that the consequent not only does, but must follow from the premises. The word “must” conveys necessity, either logical, definitional or causal. So I question whether material implication alone can be the basis of calling a logic “deductive,” even if classical forms of argumentation aside from the paradoxes give that impression. You’re defining “necessary” as “entailed by.” Is there a difference between the two?

I don’t see material implication as an excuse to invent entirely new logics to get around the paradoxes when simply defining inference in terms of necessity would be all it takes. That’s apparently what’s been done, too, at least in the book I cited. It refers to deductive logic having inferential necessity without reference to any particular logic. Some logics, like the last link you gave, seem to be oriented to ordinary language and most to mathematics and computer science. So the paradoxes of material implication might be unavoidable in a particular field. That doesn’t mean they are unavoidable in general philosophy.

Who claimed that? I certainly didn't.

The page on material implication does. Actually, what it says is that a material conditional from a contradiction is always true even if it sounds false in natural language. The example was the one about if 2 is odd, then 2 is even, to which you agree.

That’s what I mean by the conclusion that, with regard to material implication according to the article, any logical implication of an inference must be either false, irrelevant or in some way dependent on or derivative from material implication. If you accept material implication here, you cannot possibly establish a contradiction by logical implication.

I've been using phrases like 'relevantly connected' to refer to your idea that validity must require relevance.

That’s not my idea. I’ve been using “necessity.”

I've already explained how I use the term 'rationality' a number of times. ///Are you talking about classical logic here?

Yes. The lemon example you gave shows how material implication works in classical logic, and why new logics had to be invented, if I understand you.

As you know from the part of my post you didn’t copy, I clearly understand what you take rationality to mean. But your explanation is circular. That’s why I asked you to explain how any kind of entailment can obtain merely from the truth of a premise to the conclusion. It’s certainly not logical, so is the inference from propositions simply ex nihilo? Does it obtain simply by invoking the word “therefore”? I’m not asking you to justify it in terms of any other logic than itself. How did the people who used it justify the inferences? If you answer, “by inferring from the propositions,” you haven’t explained the “inferring,” so you reasoning remains circular.

Hi Zoot --

(Re: msg 322) Yes, and I keep saying that example isn’t valid for a reason. You do keep rehashing some points and ignoring responses. For example, you still seem to think I’m arguing about classical logic in this bachelors example while I’ve repeatedly said my concern was the deductive nature of the inference, or its necessity. You’re also emphasizing material implication to the exclusion of logical necessity.

I brought up Affirmation of the Consequent as an example of my concern, because in the first link you cite the AotC cannot be a fallacy as long as the consequent is true. I also read that “If 2 is odd then 2 is even” is true according to material implication. I can see that it’s true if classical logic reduces the truth of the argument to the truth of the premises in isolation, but I still don’t see how that represents an inference as opposed to a concatenation. I don’t see how the claim that “material conditionals are always true” leads to the conclusion that the logical implication of an inference must be either false, irrelevant or in some way dependent on or derivative from material implication.


Also, I'm not sure what paradox you're referring to. ///and I suppose you can call that a 'paradox' if you want.

You’re the one who provided the link and specified the section I’m now referring to. I’m calling them paradoxes because that’s what your article calls them.


All the logics that have been mentioned so far are deductive logics.

I don’t think this is the case if the premises are merely “relevantly connected.” The inference from the premises to the conclusion must be one of necessity. And no, this has nothing to do with our everyday intuitions, a point you make concerning classical logic. If you mean to say classical logic has relevantly connected premises, I’d like to hear how.


In classical logic (which, remember, is a deductive logic), "the speed of light in a vacuum is constant" necessarily follows - is entailed by - those premises.

Well, that just brings us back, once again, to my point that “necessity” is the critical term here. You appear to interpret it differently from me, but you haven’t responded whenever I’ve brought it up.


If you don't define 'rationality' the way I do, you might not agree on what it takes for an argument to be rational.

In what way are you saying the lemons syllogism was rational? According to classical logic? If so, why didn’t you specify that in the original post? You’re saying, too, that rationality to you means linking propositions inferentially. But where is the inference in a system that requires (as I understand it) only the truth of the isolated premises? And how can an inference make an argument true but not valid? If your example were rational it would, if it had an actual inference, be valid as well.

Hi Zoot --

I can't believe I'm having to explain this

I can’t either. I never claimed what you said I did. If you read my post, you’ll see you’re explaining modus ponens and Affirmation of the Consequent the way I have. My point was that P1 is a conditional which turns out to be false, as opposed to a simple statement whose truth value would be more apparent.


ANY argument of the form "if p then q; p; therefore q" is modus ponens, a valid inference in classical logic, and if both p and q are true, the argument is sound.

Ah, so Affirmation of the Consequent doesn’t really exist because p will always be true, at least according to the paradox. I suppose we can do away with the truth tables altogether since we already know the truth values in the absence of a specific statement.


The conditional may be considered false in conventional English usage, but it isn't considered false in classical logic.

Well, as an English proposition the example would be incoherent, not false. But in deductive logic it will affect the necessity of the inference.

When I say deductive, you’re coming back with classical. Frankly, I don’t know how classical the logic I’ve learned is. I’m relying mainly on an old standby, Elementary Symbolic Logic, written some time after other logics came along. Inferences are indeed a matter of necessity according to it and everything else I‘ve read. I don’t see the point of distinguishing various deductive logics if necessity already screens out irrelevant premises.


In what way does it abandon logic?

Your example in the first post is an absurdity. If some paradox of classical logic (now I’m opposing that to “deductive” logic) is okay with you, fine. But I haven't been concerned with the paradoxes because demanding necessity in the inference in modern deductive logic, such as the book I just cited, at least appears to obviate such absurdities.

We could go back to even earlier logics and the Middle Ages, I suppose, and come up with even more absurdities. But they aren’t a factor in the more modern deductive logic I’m familiar with. Your example reads as if you think the question of how many angels can stand on the head of a pin might be significant, too.

We’re talking here about the rationality of belief in God. I imagine a particular logic might be employed in such a discussion, but it would seem they’re better suited to some specific application, like computer science, than a more general question such as this. I don’t see why you want to substitute other terms for “necessity,” either, because talking about the necessity of the inference is the simplest way to evaluate the logic of the claim.


For example, any argument of the form "if p then q; not p; therefore not q" is rational in my opinion, but it obviously isn't valid on all systems of logic. As I've mentioned, I don't tie rationality to validity.

You’re qualifying each claim by saying it’s your opinion. And then you ask in what way you’ve abandoned logic? Really, how do you distinguish between rationality and validity? I’m using the terms interchangeably. If you don’t think that’s possible, why not?

Hi Bobbi --

I'm not sure we always dipense with people who don't flatter us or stick with those who do. That depends on how strong an influence others are on our esteem. Further, we can "perceive" ourselves through introspection, and our accuracy in doing so will perhaps be influenced by whether or not we think of ourselves as free agents.

Sartre's "situation limit" comes about in the context of a free will argument. You had earlier mentioned the insubstantiality of consciousness. One of Sartre's most fascinating books takes up exactly this problem. The long and the short of it is that human consciousness recognizes this insubstantiality and as a result, much of the drive in life aims at grounding ourselves somehow in material existence. Sartre calls this the pursuit of being. For him, it's the basic drive of all humans, displacing the sex drive, the survival instinct and Nietzsche's will to power. As to the free will aspect, Sartre's point is that the insubstantiality of our inner lives is the very thing that guarantees our free will, or rather our human freedom, and we should embrace our lack of substance rather than fear it.

I had lost sight of the Great Refusal. I think that's because I no longer saw it happening anywhere. However, the Arab Spring has been stunning, particularly because they had no apparent enlightenment going on. What actually did happen, especially in Egypt, also made me think more about the relevance of Rosa Luxemburg to modern outbreaks of civil disorder.

Yes, after reading the book I couldn't see what could really be done about the situation he describes, mainly because society is so atomized. But if change is possible, I've come to agree that it must entail a negative confrontation with reality as part of any process leading to more positive outcome. I still need to read Eros and Civilization, too.

Hi Andrew --

I think the Hayek quote better expresses what I'm saying. People do perceive themselves as making a free choice when it's not as free as they might think. But in a similar vein, some people will also perceive themselves as puppets lacking any choice of the matter when the fact is that they are free agents. By "choosing" to float along, I mean that the choice is there even though they don't see it. And sometimes it's hard to decide when your "situation limit" (as Sartre puts it) becomes an insurmountable barrier to your freedom to choose.

Hi Zoot --

Let’s look both your examples (bachelor and lemons) and their variable structure:


P1. If p then q
P2. q
-----
C. Therefore, p

Nothing about the sentence variables themselves indicates whether this sort of argument is true or not. Only if you plug in particular sentences can you claim modus ponens or Affirmation of the Consequent according to the truth tables. Neither of your particular examples represents a modus ponens argument. They both imply Affirmation of the Consequent because you can't argue from the conclusion C back to P1.

The reason is that P1 is false. The reason it’s false is the absence of necessity. P1 is not true precisely because of the failure of its inference. It would be true if you connected the statements with an ampersand: P1. A & B. But as it stands, at least one of your premises is false.


that statement is referring to the fact that the conditional would be considered false in conventional English usage

Linguistic convention has nothing to do with deductive logic. This is why I called the footnote a novelty. If the way we use English mattered, we wouldn’t be able to express logic using variables. Introducing conventional words doesn't change the way ordinary logic works. I could see a point to it if you could tell me how it does, something like, "Because of this discovery the concept of validity is no longer considered applicable in logic."


That's why people developed non-classical logics like relevance logic and connexive logic.

You’ve said you weren’t especially interested in other logics in this matter, so I’m referring to deductive logic. As far as I know, other logics may have been developed to handle reasoning at a level short of deductive certainty. But to claim deductive logic isn’t really deductive, you’d have to call into question what it means to be necessary. But that would be as much as to argue about whether such-and-such a deductive argument were true or false in the first place. So you still cannot sidestep the issue of necessity in an inference derived by deductive logic.


How on earth did you come to conclusion that I advocate that we 'abandon logic'? I've never said anything like that.

You yourself said as much in message 295, responding to Robert. You say all you have to do is link propositions inferentially, but then you say this is a matter of opinion and hence a subjective operation. You said arguments don’t need to be valid to be rational, but your rationality again seems to be a subjective judgment. Robert asked in message 294 So basically, you're saying that, in your opinion, any remotely comprehensible arrangement of words into an argumentative statement constitutes a rational argument? and you said sure. In what way does that uphold logic, rather than abandon it? I gather from other comments that you don’t think any logic can have an objective reference point, but that raises epistemic questions that go beyond the question of necessity. Your point seems to be that logic, to the extent that it exists at all, is purely subjective, a kind of private language.

Hi Zoot --

I'm afraid your conclusion is mistaken. You're looking at "(B)→(C) is true" and ignoring that the argument "may be considered false, because there is no discernible connection between (B) and (C)". That's exactly the basis of deductive logic. That's what I've been trying to say. If you were to take B-->C as the basis of your reasoning, it would amount to Affirmation of the Consequent, at least based on the way the article explains it.

This leads back to the question I posed before. Why don't we just abandon logic the way you suggest? If the last part of that example were decisive, that's what we would have to do. But this example has no effect on the actual practice of logic. Logic was invented by humans for human purposes. It works. Because it works it cannot be so easily undermined.

This is why people don't just lie down and die in the face of every paradox or linguistic novelty that comes down the pike. I think you're fascinated by the esoteric quality of the example, but one has to take care not confuse it with the nuts and bolts of logic or get too carried away with the many "gotchas" lying around in philosophy.

Hi Zoot --

I usually don't follow links that come with the instruction to "go read it," but I finally bit this time. Nothing in the article supports your claim. You need to read the examples a little closer.

I can see now why "I'm not going to write a bunch of essays for you guys" is about all we're going to get out of this discussion. I thought you were just inexperienced at communicating your ideas. Now I see it is something else.

I've read Marcuse in One-dimensional Man. I have to say I found it quite useful (and somewhat disturbing) to my own understanding of the political and social structure of modern societies.

Hi Zoot --

What you're talking about is material conditionals. The only relevance they have to this discussion is that they require necessity of some sort, three kinds to be exact. Since they can be expressed as arguments, all they do is make my point that the connection between a premise and a conclusion must be a necessary one.

Any other kind of logic would be inductive, but that's not to say they're subjective. However, since you say you weren't particularly interested in relevance logic or any kind other than what we're discussing, let's stick to ordinary deductive logic because the question is one of necessity. That is the point you yourself have pursued since your first post (msg 284) with reference to inference and validity, and with the example you've given.

With regard to that, your posts, taken as a whole, argue that logic is a matter of subjective opinion. That's the basis of your critique. If you think that, then you're not doing philosophy in any way and you're misrepresenting logic. There is a clear distinction between rationality and opinion.

As charitably as I can discern it, what you're saying is that inference in argumentation is a purely subjective matter. Again, that's as much as to say that reasoning boils down to opinion and the two are indistinguishable.

But that's my understanding, and I may be mistaken. However, Robert is correct. You're not offering enough background or information for anyone to understand your point, and you're responses come in the form of flat assertions, dismissals of points as "irrelevant," or comments that you don't care if someone takes your position seriously or not.

I'm assuming you're posting in good faith, not to jerk other posters around. So I'm guessing that you're simply inexperienced at putting forth an argument in a forum such as this. The problem I'm having isn't what you're saying, but the way you're answering. Your posts are not helping me gain a solid understanding of you views.

Hi Zoot --

That argument is most definitely valid and sound in classical logic. It's because of the nature of material implication.

If we're talking about deductive logic, the inference to the conclusion has to have some necessity to it. I'll have to ask you what you mean by material implication, since that's your key point, and how that applies to a deductive argument, and what counter-intuitive consequences there are to it.

You're saying that there are other logical systems out there that could make your original argument valid, but you appear to be saying also that even under the rules of ordinary deductive logic, your original argument is still valid.

If that were true, there would be no point to deductive logic because it wouldn't tell us anything. But since that logic is employed all the time in the way I'm using it, I find it unlikely that I'm mistaken.