214 replies to this topic

[Michael S. Pearl]

In order for any sort of expression to be a truth, it must refer to something, whether explicitly or not. A characteristic of this referencing is that it always claims that whatever is referenced is what can be called a determinate matter, state, condition, or context – which is to say that what is being referenced is described as being set or settled or definite.

Qualifiers such as likely, possibly, and probably – in and of themselves – essentially deny that what is being referenced is a determinate or settled matter.

For example, the statement “Bob wears a hat on Wednesday”, expressly claims a determinateness which is absent from statements such as “Bob might wear a hat on Wednesday” or “It is possible that Bob wears a hat on Wednesday” or “Bob probably wears a hat on Wednesday.”

In order for a matter to be possibly true, the matter being referenced has to be a matter which is not settled; it has to be a matter which is to some extent indeterminate. To say that something is possibly true is also to say that it is possibly false; to say that something is possibly true is to say that there is indeterminateness with regards to how the referenced matter is (to be) settled or determined. [1]

However, what is incoherent is to claim that a statement about something is both a truth and possibly true. This is because it is incoherent to claim that something is both true (or a truth) and possibly false – which is precisely what would be claimed were something ever to be described as both true and possibly true or as a truth and a possible truth. [2]

To claim that something is a truth is to claim that it is a determinate matter.

To claim that something is a determinate matter is to claim that alternatives are not compossible.

To claim that something is a determinate matter is concurrently to claim that it is concurrently impossible for alternatives to be true.

To claim that something is true is to deny the truth of alternatives.

It is only in indeterminate conditions that alternative possibilities are compossible, but, so long as there is indeterminateness, none of the alternative possibilities by themselves are true (or truths).

Determinateness is a characteristic necessary for truth.

*****************************************************

[1] Even indeterminate states or conditions can be expressed as truths. For instance, the statement, “It is possible that Bob wears a hat on Wednesday, and it is possible that Bob does not wear a hat on Wednesday” can be determinate – and, therefore, a truth – so long as the conjoined contraries exhaustively account for the possibilities and definitely describe the constituent indeterminateness.

[2] It is important to note that possibility and contingency as well as possibly and contingently are not identical or interchangeable pairs of terms, despite the fact that many discussions in modal logic or possible worlds terms might make it seem that these words are necessarily identical and interchangeable. As discussed in the text, it is incoherent to claim that something is both true and possibly true; however, there is no such incoherence when something is claimed to be both true and contingent or contingently true.

[Chato]

Not to be picky, but...

"Bob wears a hat on Wednesday?"

Shouldn't it be, "Bob always wears a hat on Wednesdays?"

Dave

[Michael S. Pearl]

Chato, on 23 November 2010 - 09:56 PM, said:

Shouldn't it be, "Bob always wears a hat on Wednesdays?"

The reason why the statement, “Bob wears a hat on Wednesday”, seems stilted is because it is essentially a template abstracted from its many conceivable variations. What is important about the abstracted template form of the statement here used as an example is that the point about the determinateness characteristic holds invariantly regardless of whether the discussion is being conducted in epistemological, metaphysical, ontological, or logical contexts (and any combinations thereof).

A schematic for variations of the original statement can be put this way:

Bob [did/does/will] wear a hat on [each/every/some particular] Wednesday.

The "Bob always wears a hat on Wednesdays" example can be restated (even if it is somewhat cumbersome) as "Bob [does] wear a hat on [every] Wednesday." That statement could, of course be made more specific by explicitly limiting the claim to some range of dates (for instance, some range during which Bob is alive), but the point remains that the statement claims (to describe) a determinate condition or state (commonly discussed in philosophical circles as a state of affairs) -- as it must in order for the statement to be a truth, in order for someone to say that the statement is a truth.

Michael

[davidm]

Michael S. Pearl, on 23 November 2010 - 08:49 PM, said:

However, what is incoherent is to claim that a statement about something is both a truth and possibly true.

I beg to differ.

Let us consider the following proposition: "It cannot be the case that a proposition is both true and possibly true." That seems to be what you are saying above.

Hence it seems that you are arguing as follows:

"A proposition cannot both be true and possibly true; hence it follows that a true statement cannot possibly be true."

Is that what you intend? I can't imagine that it is.

In fact, all true statments are possibly true; indeed all true statements are neccessarily possibly true. There is a separate class of true statements that are not just possibly true but necessarily true, and such statements are necessarily necessarily true.

[Michael S. Pearl]

davidm, on 24 November 2010 - 12:50 AM, said:

Michael S. Pearl, on 23 November 2010 - 08:49 PM, said:

However, what is incoherent is to claim that a statement about something is both a truth and possibly true.

I beg to differ.

Keeping in mind the distinction noted between possibly and contingently, on what basis could someone deny that something which is possibly true is also possibly false?

davidm, on 24 November 2010 - 12:50 AM, said:

In fact, all true statments are possibly true; indeed all true statements are neccessarily possibly true. There is a separate class of true statements that are not just possibly true but necessarily true, and such statements are necessarily necessarily true.

Although the remark noted above does not engage (or, therefore, refute) the logic of the opening post, it is interesting that the above quoted remark distinguishes between:

1. "necessarily possibly true", and
2. "necessarily necessarily true".

The second type of true above is taken as indicating a modally necessary truth - a truth which is not (and is never) possibly false. As noted in the opening posting, "[t]o say that something is possibly true is also to say that it is possibly false"; in contrast, that which is necessarily true is a truth which cannot be false. This means that even according to the above quoted response, not all truths are possible truths inasmuch as some truths are not possibly false.

What the opening posting demonstrates is that it is not just modally necessary truths which are not possibly false; what the opening posting demonstrates is that an unqualified truth, which is to say a statement put forth as true without reservation (even if in a given context), is also put forth as pertaining to something that cannot be false. Such a statement would be qualified as possibly true if and only if what were being claimed is that the statement is also possibly false.

The designations possibly true and possibly false cohere so long as indeterminateness is constituent of the referenced state.

While it is not coherent to claim that a statement of unqualified or unreserved truth is a possible truth, since such a statement is put forth indicating that it is not possibly false, it can be coherent to claim that a statement of unreserved truth (such as a context dependent truth) is a contingent truth rather than a modal necessity.

Michael

[Chato]

I am reminded of the fable about a King who wished to appear wise, and hired men to think up a saying that would always be true. After prolonged research, they arrived at the following: "This to shall pass."

To that I would add, "The Universe is."

Other than the two above, what can you say that would always be true? Certainly not poor Bob, who I just ran into on the street, pounded him into the ground and torched his hat...

Dave

[davidm]

Michael S. Pearl, on 24 November 2010 - 02:38 AM, said:

davidm, on 24 November 2010 - 12:50 AM, said:

Michael S. Pearl, on 23 November 2010 - 08:49 PM, said:

However, what is incoherent is to claim that a statement about something is both a truth and possibly true.

I beg to differ.

Keeping in mind the distinction noted between possibly and contingently, on what basis could someone deny that something which is possibly true is also possibly false?

Where have I denied that?

[Michael S. Pearl]

Chato, on 25 November 2010 - 01:41 AM, said:

what can you say that would always be true?

As noted here, a statement which is always true because it "is not (and is never) possibly false" is what is known as a modally necessary truth. Possibly the most interesting thing about such truths, as noted by Robert Nozick in his book, Invariances, is that they tend to "be a little thin, giving up depth of content for breadth of application."

This characteristic should be expected, because for a truth to be a modally necessary truth it must be true regardless of context - which is to say such truths are invariantly true across contexts. Of course, contexts are defined or determined by the details of content; therefore, we realize modally necessary truths by removing or filtering out details in order to recognize what details happen to extend across other contexts. We give up contextual details in order to see a greater "breadth of applica[bility]".

Whether we actually come up with any statements, any truths, that extend across all contexts is not really as important as many philosophical sorts often seem to make it out to be, because, eventually, we must return to the details. Accordingly, what we primarily seek are the limits of applicability - not just in philosophical matters but also, as should be apparent, in such a related matter as science.

Michael

[Michael S. Pearl]

davidm, on 25 November 2010 - 01:50 AM, said:

Michael S. Pearl, on 24 November 2010 - 02:38 AM, said:

Keeping in mind the distinction noted between possibly and contingently, on what basis could someone deny that something which is possibly true is also possibly false?

Where have I denied that?

Whether or where you have denied it is not important, since you are not (or do not seem to be) denying it at present. So, let us now revisit what I said previously. I said that "[t]o claim that something is a truth is to claim that it is a determinate matter." Determinate matter had been put forth in the very first paragraph of this thread by noting that the term indicated a state of affairs "described as being set or settled or definite."

I also noted a distinction between a truth and a possible truth, saying that "in order for a matter to be possibly true, the matter being referenced has to be a matter which is not settled; it has to be a matter which is to some extent indeterminate."

Since truth has been noted to refer to a determinate state of affairs, and since possible truth has been noted to refer to an indeterminate state of affairs, it is incoherent to claim that a statement about something is both a truth and a possible truth (or possibly true), because that would be to claim that the referenced state of affairs is both determinate and indeterminate (in contrast, as has been noted, it is not incoherent to claim that indeterminateness is constituent of a determinate state of affairs).

Once it is realized "that something which is possibly true is also possibly false", which is to say of something that it is possibly true is the same as saying that it is possibly false, then it is obvious that "possibly false" can be substituted for "a possible truth" in the statement, "Something is both a truth and a possible truth", so that the result is the strikingly incoherent claim that "something is both a truth and possibly false." The only way to avoid this incoherence would be to say that "something is both a possible truth and possibly false", but, then, the "something" being referenced would no longer be claimed as being a determinate matter (even though the conjoining of possible truth/possibly true and possibly false - so long as it is exhaustive - does produce a determinate state of affairs, one for which indeterminateness is constitutive).

Possible points of contention based upon the foregoing can include whether possible and contingent are distinguishable and whether determinateness is necessary for truth.

I have maintained that possible and contingent are distinguishable, and the following reiteration with rephrasing might make this more clear.

Whereas to say of something that it is true is to say that it is a settled or determinate matter, to say of something that it is possibly true is to say that it is an unsettled or indeterminate matter.

While it is incoherent to say of something that it is both true and possibly true/possibly false, it can, on the contrary, be perfectly coherent to say of something that it is true and contingently true.

It can also be coherent to say of something that it is true and necessarily true (in the modal sense of necessary). That which is necessarily true (modally speaking) can never be false. This is to say that a (modally) necessary truth is true regardless of context or in all contexts; a modally necessary truth is context-independent. A contingent truth, on the other hand, is context-dependent.

To say of something that it is true is to say that it is (at the very least contingently) not possible for it to be (or that it is) otherwise. It is possible that it be otherwise only given a contextual indeterminateness, but to claim of something that it is determinate without constitutive indeterminateness is to deny that there is any indeterminateness in the context or state of affairs being described as true.

Such a distinction between possible and contingent precludes the modal fallacy. This, then, leaves the question of whether there is any contention over the claim that determinateness is necessary for truth (even though determinateness is not necessary for a possible truth).

Michael

[davidm]

All true propositions about actual states of affairs in the world are also possibly true, unless they are necessarily true.

That means that all true statements, unless they are necessarily true, are also possibly false.

It is actually true that JFK was assassinated, but not necessarily true; it is, was, and always will be, possibly false that JFK was assassinated. This means that there are any number of possible but not actual worlds at which JFK was not assassinated.

The actual world is a subset of all physically possible worlds.

All physically possible worlds constitute a subset of all logically possible worlds.

[Michael S. Pearl]

My previous posting was a recapitulation of the point that a truth refers to a determinate state of affairs. That posting even allowed how that might be a point of contention. The following is the response put forth:

davidm, on 25 November 2010 - 07:35 PM, said:

All true propositions about actual states of affairs in the world are also possibly true, unless they are necessarily true.

That means that all true statements, unless they are necessarily true, are also possibly false.

It is actually true that JFK was assassinated, but not necessarily true; it is, was, and always will be, possibly false that JFK was assassinated. This means that there are any number of possible but not actual worlds at which JFK was not assassinated ...

Of course, the quoted posting is not actually responsive; accordingly, it might be most accurate to describe that posting as being immediately subsequent rather than to describe it as responsive or as a response. That posting neither agrees nor disagrees with the claim that determinateness is necessary for truth (given the distinction which has been made between truth and truth qualified by a modifier such as possible); that posting ignores the determinateness issue altogether -- so much so, that the posting does not even address the determinateness issue with regards to truths which are modally necessary.

In addition, that immediately subsequent posting neither agrees nor disagrees with the point made about possibility and contingency having distinguishable meanings.

That posting also claims the statement "JFK was assassinated" is "actually true ... and always ... possibly false". Of course, in this post-1963 actuality, it is not possible for the statement "JFK was assassinated" to be false. In other words, in this post-1963 actuality, the statement "JFK was assassinated" is not "possibly false". The reason why it is not possibly false is that it is, presumably, a (wholly) determinate matter that JFK is assassinated in 1963 of this actuality. And, because it is a determinate matter, it is true that JFK is assassinated in 1963 of this actuality. In this 2010 actuality, it is not possibly true that JFK is assassinated in 1963 of this actuality; it is, instead, true. That truth is contingently true, but it is not possibly true, because it is not possibly false.

It is important to understand that a matter can be determinate, hence true, without being actual.

For instance, in a non-eternalistic (hard) determinism, the future is said to be always determinate; therefore, within in that context, it is perfectly coherent to claim as true (since it is a determinate matter) something which is not actual -- even if that which is true is said to be contingently true.

So, to this point, the claim that determinateness is necessary for truth has neither been refuted nor undercut, and, to this point, the claim that it is incoherent to say of something that it is both true and possibly true/possibly false has neither been refuted nor undercut.

Michael

[davidm]

Michael S. Pearl, on 26 November 2010 - 02:11 AM, said:

Michael

Michael, if by "determinate" you mean that an event must occur before there is a true statement about it, I disagree, of course. A man who in 1380 said, "Obama will be elected president in 2008" spoke a truth. Propositions do not exist in a particular places in space or time. They are abstract objects and propositions are timelessly true or false.

I do agree that that act or event provides the truth grounds for a true proposition about it, and so as William Lane Craig wrote:

Quote

It is I by my freely chosen actions who supply the truth conditions for the future contingent propositions known by God. The semantic relation between a true proposition and the corresponding state of affairs is not only non-causal, but asymmetric, The proposition depends for its truth on which state of affairs obtains, not vice versa. Were I to choose otherwise than I shall, different propositions would have been true than are, and God's knowledge would have been different than it is. Given that God foreknows what I shall choose, it only follows that I shall not choose otherwise, not that I could not. The fact that I cannot actualize worlds in which God's prediction errs is no infringement on my freedom, since all this means is that I am not free to actualize worlds in which I both perform some action a and do not perform a.

He is explaining that future contingents can be true before the events they describe, and why this is so. Norman Swartz also explained this, pointing out, as Craig does above, that the semantic relation between a true proposition and the corresponding state of affairs is non causal, so there is no worry here of events somehow causing prior statements about them to be true via some backward-in-time causal influence.

Of course it is possibly false that JFK was assassinated. As I've explained, he was assassinated in the actual world. But, as I also explained, the actual world is a subset of all physically possible worlds, all of which are non-actual except the actual world. And all physically possible worlds are a proper subset of all logically possible worlds. There is also a possible world at which pigs talk, donkeys fly and the moon is made of Roquefort cheese. It's just not the actual world.

[Michael S. Pearl]

davidm, on 26 November 2010 - 02:41 AM, said:

if by "determinate" you mean that an event must occur before there is a true statement about it, I disagree, of course.

No. That is not what I mean, and evidence that I mean no such thing is the sentence from my previous posting in which I said, "It is important to understand that a matter can be determinate, hence true, without being actual."

In order to express truth, it is necessary to refer to a determinate matter, which is to say that what is being referenced is - and is depicted as being - set or settled or definite (as in definitely the case). Is this a contentious statement?

davidm, on 26 November 2010 - 02:41 AM, said:

[Craig] is explaining that future contingents can be true before the events they describe ...

Of course "future contingents can be true before the events they describe" obtains. I have already said as much. Now let us take a look at part of what else you quote Craig as saying:

The proposition depends for its truth on which state of affairs obtains, not vice versa.

Notice that Craig's truth refers to a determinate state of affairs, and notice that the state of affairs to which he refers is not one in which the person acts one way or another. Rather, the state of affairs to which he refers is one in which the person acts in only one way.

Does the meaning of Craig's remark differ in any way from my statement that in order to express truth, it is necessary to refer to a determinate matter, which is to say that what is being referenced is - and is depicted as being - set or settled or definite (as in definitely the case)?

Michael

[davidm]

Michael S. Pearl, on 26 November 2010 - 02:52 PM, said:

davidm, on 26 November 2010 - 02:41 AM, said:

if by "determinate" you mean that an event must occur before there is a true statement about it, I disagree, of course.

No. That is not what I mean, and evidence that I mean no such thing is the sentence from my previous posting in which I said, "It is important to understand that a matter can be determinate, hence true, without being actual."

In order to express truth, it is necessary to refer to a determinate matter, which is to say that what is being referenced is - and is depicted as being - set or settled or definite (as in definitely the case). Is this a contentious statement?

davidm, on 26 November 2010 - 02:41 AM, said:

[Craig] is explaining that future contingents can be true before the events they describe ...

Of course "future contingents can be true before the events they describe" obtains. I have already said as much. Now let us take a look at part of what else you quote Craig as saying:

The proposition depends for its truth on which state of affairs obtains, not vice versa.

Notice that Craig's truth refers to a determinate state of affairs, and notice that the state of affairs to which he refers is not one in which the person acts one way or another. Rather, the state of affairs to which he refers is one in which the person acts in only one way.

Does the meaning of Craig's remark differ in any way from my statement that in order to express truth, it is necessary to refer to a determinate matter, which is to say that what is being referenced is - and is depicted as being - set or settled or definite (as in definitely the case)?

Michael

Well, I'm at a loss to understand what you are arguing.

Of course, a person acts one way or another. He cannot act both ways. That would be a logical contradiction. Craig's point is that if the man freely chooses a, then God will foreknow a. But if he freely chooses not-a, then God will foreknow not-a. So the man is free to bring either a or not-a into actuality, but not both. And whatever he chooses, God will foreknow. And just so, even without invoking God, whatever the man does, there will be a contingent proposition that will reflect the truth of his action.

Do you disagree?

[Michael S. Pearl]

davidm, on 26 November 2010 - 03:12 PM, said:

Of course, a person acts one way or another.

That is not the issue at hand. The issue at hand pertains to the truth(s) about, for instance, a person's acts.

davidm, on 26 November 2010 - 03:12 PM, said:

Craig's point is that if the man freely chooses a, then God will foreknow a. But if he freely chooses not-a, then God will foreknow not-a. So the man is free to bring either a or not-a into actuality, but not both.

One problem with the Craig argument as put forth immediately above is that no relevance has been established to the topic at hand regarding truth, including, specifically, the determinateness claimed to be necessary for truth.

davidm, on 26 November 2010 - 03:12 PM, said:

whatever the man does, there will be a contingent proposition that will reflect the truth of his action.

Do you disagree?

An aspect of the determinateness issue pertaining to truth is the matter of whether - or under what conditions - it is coherent to say that it is true that a person will do something.

The analysis put forth in my previous posting establishes (or, at the very least, strongly suggests) that Craig agrees "that in order to express truth, it is necessary to refer to a determinate matter, which is to say that what is being referenced is - and is depicted as being - set or settled or definite (as in definitely the case)." That agreement being the case, the focus rightly shifts to what conditions would be required in order for it to be coherent to say that it is true that a person will do some particular act or be some particular way. None of the Craig positions reported to this point address or pertain to the conditions required for such a coherent expression.

Michael

[davidm]

Michael, I must confess I do not follow your arguments. I'm not sure what you're trying to say here.

What would help is to give some examples, actual events and statements about them, to clarify your arguments.

[Michael S. Pearl]

davidm, on 26 November 2010 - 11:54 PM, said:

What would help is to give some examples, actual events and statements about them, to clarify your arguments.

It is quite simple really. Think of an instance when you say of anything that it is true or a truth. Are you referencing what you regard as a determinate matter? How do you refer to things about which you think that they only might be true?

Michael

[davidm]

Michael S. Pearl, on 27 November 2010 - 12:58 AM, said:

davidm, on 26 November 2010 - 11:54 PM, said:

What would help is to give some examples, actual events and statements about them, to clarify your arguments.

It is quite simple really. Think of an instance when you say of anything that it is true or a truth. Are you referencing what you regard as a determinate matter? How do you refer to things about which you think that they only might be true?

Michael

If I don't know whether something is true or not, I say it might be true or it might be false.

[mosaic]

Michael, do you make a distinction between the meaning of a sentence and its truth conditions? This seems implicit in your argument. You don't seem to accept, for example, that truth is a property of sentences as such - the view point implicit in what you're arguing against.  For example, if I say "The Saints will lose next week" or "The Broncos will rise...next year" would you hold that neither statement, strictly speaking, is true or false?  It doesn't seem you would "strictly speaking"  because you would qualify that they aren't true or false by the further stipulation that the events in question are not yet ( or so we think) determinate. In other words, your concern is not  so much the sentence as the conditions that confer truth to it. In order for a sentence to be true, it must be a "determinate" matter. Thus, a sentence could be true before an event so long as this event is "determinate." If the event is not determinate, however, the sentence cannot be true or false. Here, we would simply have to resort to qualifiers like "possibly" which express  the "indeterminate" state of affairs we which to capture.   Is this an accurate summary?

Edited by mosaic, 27 November 2010 - 07:11 AM.

[Michael S. Pearl]

mosaic, on 27 November 2010 - 07:10 AM, said:

if I say "The Saints will lose next week" or "The Broncos will rise...next year" would you hold that neither statement, strictly speaking, is true or false? It doesn't seem you would "strictly speaking" because you would qualify that they aren't true or false by the further stipulation that the events in question are not yet ( or so we think) determinate.

Right. If it is a determinate matter that the Saints will lose next week, then any expression of that determinateness would be true, would be a truth, prior to the loss. To say the Saints will lose next week is to say that it is true this week that the Saints will lose next week. That, in turn, is to say that it is being claimed that it is a determinate matter that the Saints will lose next week.

Reference to a loss by the Saints is true from whatever perspective that outcome is a determinate matter.

In other words, were eternalism true, it can be perfectly coherent to say that it is true the Saints will lose next week. Likewise, if a non-eternalistic determinism is the case, then it can be perfectly coherent to say that it is true the Saints will lose next week The reason why it would be coherent to speak in such a way in both of these perspectives is that each of these perspectives in themselves assert the determinateness necessary for the truth to be that the Saints will lose next week.

On the other hand, if such a thorough determinateness is not the case or is not presumed to be the case, and if it is not the case that it is a determinate matter that the Saints will lose, then it is at the very least incorrect to say that it is true that the Saints will lose next week.

What would be incoherent is to say that it is true that the Saints will lose next week and that it is possibly true that the Saints will lose next week. Of course, if someone said something like that in conversation, the introduction of the "possibly true" could be interpreted as some sort of movement away from definitiveness to probability.

However, other than in a casual conversation, which is a conversation in which rephrasing for the sake of greater accuracy can often tend towards inappropriateness, the conjoining of the it is true and the it is possibly true is made more clearly incoherent by the following substitutions:

1. The "possibly true" can be replaced by "possibly false" - without change of meaning - so that the claim becomes: It is true that the Saints will lose next week, and it is possibly false that the Saints will lose next week. This claim is incoherent. In order for it to be made coherent, it would be necessary to add "possibly" to the first true to say: It is possibly true that the Saints will lose next week, and it is possibly false that the Saints will lose next week.

2. Alternatively, "determinate matter" could be substituted for "true" - once again without changing the meaning  - inasmuch as determinateness (as has been discussed previously) is necessary for truth. Likewise, "indeterminate matter" can be used in place of "possibly true" (also as previously discussed). This gives the statement: It is a determinate matter that the Saints will lose next week, and it is an indeterminate matter that the Saints will lose next week. What would not be incoherent is to say that: It is an indeterminate matter that the Saints will lose next week, and it is an indeterminate matter that the Saints will win next week.

mosaic, on 27 November 2010 - 07:10 AM, said:

In other words, your concern is not so much the sentence as the conditions that confer truth to it.

I am not so sure this is the case. I think that my concern regards both. After all, the statements at issue here just are those sorts which are claimed to be expressions about determinate matters -- which is to say they are claimed to be truths.

mosaic, on 27 November 2010 - 07:10 AM, said:

In order for a sentence to be true, it must be a "determinate" matter.

Yes. A truth is an expression which refers to a determinate matter.

mosaic, on 27 November 2010 - 07:10 AM, said:

Thus, a sentence could be true before an event so long as this event is "determinate."

Yes. This would be the case of an expression referring to a determinate matter.

mosaic, on 27 November 2010 - 07:10 AM, said:

If the event is not determinate, however, the sentence cannot be true or false. Here, we would simply have to resort to qualifiers like "possibly" which express the "indeterminate" state of affairs we which to capture. Is this an accurate summary?

Well, I guess it could be said that a statement which asserts determinateness about an indeterminate matter would be false, but, yes, it is better, it is more constructive "to resort to qualifiers like 'possibly' which express the 'indeterminate' state of affairs" being referenced.

Michael

[davidm]

If one is a presentist, it seems that future contingents have no truth value, because the future does not (yet) exist. The problem here is that such sentences about the future do not refer, and it is commonly held that meaningful propositions cannot refer to nonexistent states of affairs.

This is not a problem for eternalism.

But, because, under presentism, the past does not exist any longer, than propositions about the past do not refer, either. On this account, one cannot truthfully say, “JFK was assassinated on Nov. 22, 1963.” This is a big problem for presentism (not it’s biggest problem, surely; it’s biggest problem is that it’s empirically false.)

I’ll just note again that it’s perfectly coherent, indeed it’s logically invalid to hold otherwise, that true statements are also possibly true or possibly false (unless they are necessarily true statements). This is because the actual world is a subset of all physically possible worlds, which in turn is a subset of all logically possible worlds. So, necessarily, all actual worlds are possible worlds, but the converse is obviously not true: Not all possible worlds are actual worlds (except for David Lewis). From this it follows that a true statement is also possibly true.

[Michael S. Pearl]

davidm, on 27 November 2010 - 06:02 PM, said:

From this it follows that a true statement is also possibly true.

In part, the discussion to this point can be understood as indicating an expressive ambiguity and its resolution. So long as it is the case that an expression is true if it refers to a determinate matter such that something is possibly true at the very least so long as it is an indeterminate matter, then it is incoherent to claim of an action, for instance, that it is both determinate that it is done and not determinate, meaning that it is not done although it might still be done. Indeed, if the matter is indeterminate, the only coherent expression is to (mean to) say that it is possibly true that the action is (or will be, or -- conceivably in a strictly epistemological context, for example -- has been) done.

This is where the distinction between possibly and contingently can be used to improve the accuracy of expression. Some state of affairs can be determinate, which is to say true, while also being contingently true. The contingently here indicates that there might have been some indeterminateness about the matter, but that indeterminateness is since transformed into a determinate state such that the state of affairs is no longer possibly true but, instead, true because it is determinate.

Michael

[davidm]

A contingent truth refers to a statement that is true in our own world, but not true in all possible worlds (else it would be necessary).

A statement that is true in some possible world, not necessarily our own, is a possible truth.

[Michael S. Pearl]

davidm, on 27 November 2010 - 07:39 PM, said:

A contingent truth refers to a statement that is true in our own world, but not true in all possible worlds (else it would be necessary).

A statement that is true in some possible world, not necessarily our own, is a possible truth.

How does any of that fail to fit with what I have written?

Michael

[davidm]

Michael S. Pearl, on 27 November 2010 - 07:46 PM, said:

davidm, on 27 November 2010 - 07:39 PM, said:

A contingent truth refers to a statement that is true in our own world, but not true in all possible worlds (else it would be necessary).

A statement that is true in some possible world, not necessarily our own, is a possible truth.

How does any of that fail to fit with what I have written?

Michael

I don't think it does. I'm not even sure what we're supposed to be disagreeing about, if anything.

I think my only cavil is you keep saying that it's incoherent for a statement to both be true and possibly true. But logically speaking, the opposite of that would be to say that a statment is both true but not possibly true, which is a logical contradiction.