Maverick Philosopher

Nihil philosophicum a me alienum puto

To promote independent thought about ultimates. Philosophy, commentary on the passing scene, and whatever else turns my crank. Since 4 May 2004. By William F. Vallicella, Ph.D., Gold Canyon, Arizona, USA. Motto: "Study everything, join nothing." (Paul Brunton) Latin Motto: Omnia mea mecum porto. Turkish motto: Yol bilen kervana katilmaz. (He who knows the road does not join the caravan.) All material copyrighted.

Thursday, March 27, 2008

Gratuitous Evil and Begging the Question: Does LAFE Beg the Question?

What is it for an argument to beg the question? I suggest that an argument begs the question if it is impossible to know one of the premises to be true without knowing that the conclusion is true. The simplest question-begging arguments are of the form

p
---
p.

Clearly, every argument of this form is valid, and some arguments of this form are sound. It follows that an argument can be sound and yet probatively worthless. In plain English, no argument of the above form proves its conclusion in the sense of giving a 'consumer' of the argument any reason to accept the conclusion; it rather presupposes its conclusion. One cannot know the premise to be true without knowing that the conclusion is true.

Posted by William F. Vallicella on Thursday March 27, 2008 at 4:20pm. 27 Comments 0 Trackbacks

Friday, December 7, 2007

The De-Mathematisation of Logic
This just over the transom:


Posted by William F. Vallicella on Friday December 7, 2007 at 7:47am. 15 Comments 0 Trackbacks

Friday, November 23, 2007

Five Grades of Self-Referential Inconsistency: Towards a Taxonomy

Some sentences, whether or not they are about other things, are about themselves. They refer to themselves. Hence we say they are 'self-referential.' The phenomenon of sentential self-referentiality is sometimes benign. One example is 'This sentence is true.' Another is 'Every proposition is either true or false.' Of interest here are the more or less malignant forms of self-reference. One example is the so-called Liar sentence:

Posted by William F. Vallicella on Friday November 23, 2007 at 6:24pm. 1 Comments 0 Trackbacks

Tuesday, November 6, 2007

The Unity of the Proposition

My logic sparring partner 'Ockham' wants to get back to logic and metaphysics. I am happy to oblige him. A topic I have not yet mentioned in these pages is that of the unity of the proposition. It is closely tied to the topics of truth and assertion that we discussed a few months ago. Assertion and Grammatical Mood is perhaps the best post I wrote during that period.

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Posted by William F. Vallicella on Tuesday November 6, 2007 at 6:53pm. 10 Comments 0 Trackbacks

Friday, July 13, 2007

Bertrand Russell on Exact Thinking

Bertie makes it to YouTube!
Posted by William F. Vallicella on Friday July 13, 2007 at 8:43pm. 6 Comments 0 Trackbacks

Monday, May 7, 2007

The Metaphysics 101 Argument for Propositions

In his SEP entry on propositions, Matthew McGrath presents what he calls the 'Metaphysics 101' argument for propositions. Rather than quote him, I will put the argument in my own more detailed way.

1. With respect to any occurrent (as opposed to dispositional) belief, there is a distinction between the mental act of believing and the content believed. Since believing is 'intentional' as philosophers use this term, i.e., necessarily object-directed, there cannot be an act of believing that is not directed upon some object or content. To believe is to believe something, that the door has been left ajar, for example. Nevertheless, the believing and the believed are distinct.

Related Posts (on one page):

  1. The Metaphysics 101 Argument for Propositions
  2. 'Ockham' on Aquinas on Singular Propositions
Posted by William F. Vallicella on Monday May 7, 2007 at 4:47pm. 10 Comments 0 Trackbacks

Sunday, May 6, 2007

'Ockham' on Aquinas on Singular Propositions

From The Logic Museum:

[. . .] The modern view of the proposition is that it is a complex or 'structured' entity that is expressed by a sentence, and that a singular proposition such as 'Socrates is a man' consists of the object referred to by the proper name 'Socrates', namely Socrates himself, plus the concept referred to by the predicate 'is a man'. This was not the traditional view at all. On the traditional view, concepts are universal only, and the only kinds of propositions are so-called particular propositions such as 'some man is wise', or universal propositions such as 'all men are mortal'. Both kinds of proposition combine universal terms such as 'man', 'wise', 'mortal' and so on. [. . .]

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Related Posts (on one page):

  1. The Metaphysics 101 Argument for Propositions
  2. 'Ockham' on Aquinas on Singular Propositions
Posted by William F. Vallicella on Sunday May 6, 2007 at 2:33pm. 17 Comments 0 Trackbacks

Friday, May 4, 2007

Frege on Logic as a Normative Discipline

Why are 'Ockham' and I having such a frightful diagreement? I say 'frightful' because if we cannot agree on such basic logical notions as that of argument validity, after all this careful discussion, then what the hell can we agree on? Something tells me that we are not going to agree on anything in regard to logic, not even what logic is. And if we can't agree on logic, then we can forget metaphysics and the rest of it. I take it he denies that logic is a normative discipline. Here is a passage from the Aristotle of modern logic, Gottlob Frege, a passage that strikes me as exactly right:

Like ethics, logic can also be called a normative science. How must I think in order to reach the goal, truth? We expect logic to give us the answer to this question, but we do not demand of it that it should go into what is peculiar to each branch of knowledge and its subject-matter. On the contrary, the task we assign logic is only that of saying what holds with the utmost generality for all thinking, whatever its subject-matter. We must assume that the rules for our thinking and for our holding something to be true are prescribed by trhe laws of truth. The former are given along with the latter. Consequently we can also say: logic is the science of the most general laws of truth. (From the draft "Logic" (1897) in Posthumous Writings, p. 128.)

Posted by William F. Vallicella on Friday May 4, 2007 at 7:47pm. 1 Comments 0 Trackbacks

Wednesday, May 2, 2007

Yet Another Round with 'Ockham' on Conditional Validity

Commenter Ockham bids us consider the following 'argument':

Alexander seized Helen
Alexander did not seize Helen
-----
Someone seized Helen and did not seize Helen.

We are to suppose that 'Alexander' does not denote the same individual in both of its occurrences.

Ockham tells us that this argument is "manifestly and undeniably of the form":

Fa
~Fa
---
(Ex)(Fx & ~Fx).

Posted by William F. Vallicella on Wednesday May 2, 2007 at 2:40pm. 16 Comments 0 Trackbacks

Tuesday, May 1, 2007

Abbreviations, Place-Holders, and Logical Form

It is one thing to abbreviate an argument, another to depict its logical form. Let us consider the following argument composed in what might be called 'canonical English':

1. If God created some contingent beings, then he created all contingent beings.
2. God created all contingent beings.
-----
3. God created some contingent beings.

Posted by William F. Vallicella on Tuesday May 1, 2007 at 4:42pm. 3 Comments 0 Trackbacks

Monday, April 30, 2007

Reasoning and Logic as Presupposing Limited Doxastic Voluntarism

My logical investigations have sent me back to that quirky but brilliant independent philosopher from America's philosophical Golden Age. I am referring to Charles Sanders Peirce.

The central problem of logic, Peirce tells us, "is the classification of arguments, so that all those that are bad are thrown into one division, and those which are good into another . . . ." (Collected Papers vol. II, Elements of Logic, p. 119, sec. 14) On this characterization of logic's task, which I accept, it is a normative discipline: logic is not concerned to describe how people reason and argue as a matter of fact, but concerned to prescribe how they ought to reason and argue if they are to attain truth. Thus logic is no part of psychology.

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Related Posts (on one page):

  1. Nota Notae est Nota Rei Ipsius and the Ontological Argument
  2. Frege on Logic as a Normative Discipline
  3. Reasoning and Logic as Presupposing Limited Doxastic Voluntarism
Posted by William F. Vallicella on Monday April 30, 2007 at 8:03pm. 23 Comments 0 Trackbacks

Sunday, April 29, 2007

Validity and Unconditional Validity

I am trying to get to the bottom of my disagreement with commenter Ockham. He sees a distinction where I see no distinction. Here is a recent attempt of his to explain his distinction:

A 'valid argument form' is not unconditionally valid, without the proviso that one and the same expression is not given a different interpretation in the course of the argument. The actual interpretation is indifferent to the logical validity of the argument, provided only that it remain unchanged throughout the argument.

If you don't find it clear I can't help you, because I took it almost verbatim from Quine's Methods of Logic, 2nd edition (1962).

I have two copies of Quine's book in my library, but consultation of the index leads to nothing quite like what O. is saying above. But let's consider what he is saying.

Posted by William F. Vallicella on Sunday April 29, 2007 at 4:36pm. 21 Comments 0 Trackbacks

Friday, April 27, 2007

Propositions and the Three Stooges

'I am happy' is a sentence of English in the indicative mood. Does it have a truth-value? No. Only an indicative sentence actually asserted by someone has a truth-value, i.e., is either true or false (on the assumption of bivalence). One may introduce propositions by saying that they are the bearers or vehicles of the truth-values. They are the entities appropriately characterizable as either true or false, whatever other roles they may play. Just what they are (abstract intensional entities? sets of possible worlds? contents of acts of judging?) is a question distinct from the role they play, and I have just introduced them by the role they play. That there must be such entities as propositions distinct from sentences strikes me as well-nigh self-evident. There are many arguments. Perhaps we will get around to them. Here is one consideration suggested by some of the puzzles lately adduced by commenter Ockham. Imagine an 'argument' enacted or deployed or put forth by the Three Stooges:

Posted by William F. Vallicella on Friday April 27, 2007 at 4:45pm. 14 Comments 0 Trackbacks

Thursday, April 26, 2007

A Specious Argument About Validity Refuted

Commenter Ockham urges the surprising thesis that the argument-form

Fa
Ga
-----
(Ex)(Fx & Gx)

is invalid. His argument for this bizarre claim makes us of the 'Alexander argument':

Posted by William F. Vallicella on Thursday April 26, 2007 at 4:42pm. 15 Comments 0 Trackbacks

Wednesday, April 25, 2007

Validity, Invalidity, and Contravalidity

If a deductive argument is valid, that does not say much about it: it might still be probatively worthless. Nevertheless, validity is a necessary condition of a deductive argument's being probative. So it is important to have a clear understanding of the notion of validity. As I have said more than once, an argument is valid if (and only if) one of its logical forms is such that no argument of that form has true premises and a false conclusion.

Posted by William F. Vallicella on Wednesday April 25, 2007 at 3:21pm. 0 Comments 0 Trackbacks

Tuesday, April 24, 2007

Of Time and Validity: Another Logical Curiosity

Commenter Ockham offers us this paradoxical tidbit:

Today is Wednesday (uttered on Wednesday, just before midnight)
If today is Wednesday, tomorrow is Thursday
Ergo, tomorrow is Thursday (but now today is Thursday!)

We know that modus ponendo ponens is valid, and the above appears to instantiate this form. But the argument cannot be valid since the premises are true and the conclusion false. So what should we say about this example?

In the previous post I pointed out that sameness of linguistic meaning is neither necessary nor sufficient for sameness of proposition expressed. Thus two assertive utterances of 'I am hungry,' though they have the same linguistic meaning, will express different propositions if different people utter them. The same holds for 'Tomorrow is Thursday.' 'Tomorrow' is a temporal indexical: it refers to the day immediately after the day on which the term is tokened.

Thus the consequent of the conditional premise is a different proposition from the conclusion. The argument therefore has the following invalid form:

p
p --> q
-----
r.

So although the argument appears to be of the form modus ponendo ponens, it is not really of that form. This is easy to see when one bears in mind that logic is concerned, not with relations between indicative sentences, but with relations between the propositions expressed by, or the starements made by, assertive tokenings (whether in the form of utterances or in unverbalized acts of thinking) of indicative sentences.