Liquidrage

It doesn't appear to follow them.
Sheesh.

The author drops the word "can" as if the difference between freewill and determinism is "can". If it was just a combination, then the word "can" would appear in 6. The author choose to drop "can".

However, as I've stated many times, the author never gave a reason why his statements (which were not truths) were able to be combined to begin with.

As I have pointed out, 6 on it's own not true, regardless of the combination used to create it.

If someone concluded,
"The sun weighs 6 oz. and is made up of mostly gold"

Would it matter what their methods were?
If the results are known untrue, then the method or the initial data is wrong.
6 and 7 are wrong. It is his "6oz. golden sun".

bd-from-kg

Taffy Lewis:

Consider the following argument:

P1) Whatever should be done can be done.

or equivalently:

P1') If I should do X, I can do X.

P2) If determinism is true, then whatever can be done, is done.

or equivalently:

P2') If determinism is true, if I can do X, I do X.

From P1' and P2' we have immediately:

C) If determinism is true, if I should do X, I do X.

or equivalently:

C') If determinism is true, everyone always does what he should do.

Now it should be clear that if the original argument is sound and valid, so is this one, since it uses precisely the same logic. And in a sense it is valid. If one holds that it cannot properly be said that a person should do something unless he “can” do it (i.e., P1) and that the sense of “can” here is that there is a nonzero probability that he will do it, then determinism does indeed imply that everyone always does what he should do. This is the basis of the often-heard claim that determinism reduces morality to nonsense or triviality.

But if this is the proper sense of “can” in P1, your first premise is plainly false: it is not true (as a general principle) that we should refrain from believing falsehoods, because obviously we are not always able to refrain from believing falsehoods. On the other hand, if some other sense of “can” is intended, your third premise is false: determinism implies that “whatever can be done, is done” only if “can” is used in this sense.

Thus, as tronvillain observed, what little plausibility this argument has at first glance is based entirely on an equivocation of the meaning of “can” in the second and third premises.

A couple of side comments:

(1) The proper sense of “can” in your second premise (i.e., the sense required to make it true) is a subject of considerable controversy. (G. E. Moore devoted an entire chapter to it in his fine little book Ethics.) But few philosophers would agree with tronvillain that the proper interpretation is that the act in question is “physically possible”. In the first place, this is too vague: “possible” involves essentially the same ambiguity as “can”. For example, in one sense of “possible”, in a deterministic world the only things that are “physically possible” are the things that actually happen. In the second place it is too loose. For example (in a common sense of “possible”) it may be physically possible for Smith to cross a rope bridge across a deep chasm to rescue a child, but psychologically impossible because Smith has a severe case of acrophobia. Few people would say that Smith “should” cross the chasm under these conditions, and is therefore to be blamed for not doing so.

2. Contrary to the claims of some of the posters here, there are no other fallacies or logical errors in this argument. All of the inferences are perfectly valid. The only problem with it is that either premise 2 or premise 3 is false (depending on what sense of “can” is used). Or alternatively, as tronvillain prefers to put it, all of the premises are true, but the inference from steps 3 and 5 to 6 is invalid because of the difference in the meaning of “can” in the second and third premises.

tronvillain

Liquidrage:
No, it does appear to follow and the word "can" is not dropped arbitarily. As should be apparent, its disappearance is a consequence of combining two and five.

Given that they are just sentences, there is no apparent obstable to combining them, except (as I have stated many times) that use different senses of the word "can."

We are all aware that six is not true, thank-you very much. The problem is explaining why it is not true if you accept the previous statements, which I have done. Of course, if you reject one or more of the statements, there is no problem at all.

tronvillain

bd-from-kg: I wasn't attempting to imply that physical possibility was sufficient for a should statement (hence my addition of "at least in principle), but I do think it is necessary for one. Something has to be at least physically possible (the laws of physics do not prohibit such a state of the world) in order for someone to say it should be done.

Liquidrage

I've stated why many times.

5. With respect to the free-will issue, we can refrain from believing falsehoods

This says nothing about determinism.

However, the author chooses to combined it with a definition of determinism.

This is what is used to produce 6.

Liquidrage

Of course, if you reject one or more of the statements, there is no problem at all

Yes, I've stated that many times.

1. With respect to the free-will issue, we should refrain from believing falsehoods. (premise)

2. Whatever should be done can be done. (premise)

3. If determinism is true, then whatever can be done, is done. (premise)

4. I believe MFT. (premise)


Of these 4, only #3 contains any resemblence to a truth. I do not just mean by definition either. 1,2 and 4 do not provide a foundation on which to build further conclusions because they are non factual statements. They do not prove not explain anything.

Non of these are valid "a's" in a
if a then b
statement.
except for 3 (semantics and quantum uncertainty aside)

Take number 1 for example.
There is no reason that the word "determinism" cannot appear there. Or for that matter any system of belief of philosophy.

ex.
With respect to the determinism issue, we should refrain from believing falsehoods

Nnumber 2 is irelevant to either of the topics at hand. It says not for nor against free will or determinism

4 is a belief

Are determinism and free will universal opposites? No. There are many aspects that are properties of both, such as "can" and "choose".

Taffy Lewis

bd-from-kg:

You make a distinction between two different senses of the word "can". Your first is:

You only alluded to another sense in your statement:

What other sense of "can" did you have in mind?

Further, you said:

I don't see how replacing the word "can" with the word "able" sheds any light on the issue. The author might just say "If determinism is true then you are not ABLE to refrain from believing falsehoods no matter what you believe."

Lastly, you said:

The proponent of the argument would certainly deny that "Smith should rescue the child." if it is psychologically DETERMINED that he will not.

Liquidrage

The proponent of the argument would certainly deny that "Smith should rescue the child." if it is psychologically DETERMINED that he will not

Determinism does not disallow the word "should".

For example, it is perfectly acceptable to use the world "should" in reference to non living entities that are obviously deterministic.

"The program should work now."
"The bomb should go off in 10 minutes"

I borrowed this from a web site as I feel it is needed here.

If you look at the structure of any deductive argument, you will notice that each of them can be expressed as a conditional statement, with the conjunction of all the premises serving as the antecedent and the conclusion serving as the consequent. With this in mind, we can use truth tables to find out the validity of different argument forms which do not match (immediately) any of the known valid forms.

I will now walk away from this discussion as myself and everyone else are clearly on different pages. I leave you all in peace to ponder the "should" "believe" and "can" truth tables.

owleye

Taffy:

"8 is supposed to follow from 7 because believing in determinism is supposed to lead to a contradiction (ie. determinism's truth coupled with my avoiding a falsehood while believing in free will)"

It's not the "believing in determinism" that is supposed to lead to a contradiction, rather it is determinism itself coupled with premise 1 that leads to a contradiction (assuming very reasonably that 7 is true). This, according to some reductio principle, would make determinism false, but not necessarily that free-will exists. You'd probably need another premise.

However, I am suspicious of the use of logic when beliefs are attached to statements.

I would concede only to the point that it is rational to believe whatever is true. Its truth is presumably independent of whether or not it is believed. In the absence of a determination of the truth of determinism and/or free-will, rationality might enter into it if there were ample (or sufficient) grounds for one and/or the other or that, in an evidentiary sense, there is a preponderance of evidence to support one over the other (two). However, this is a far cry from being a proof of one and/or the other.

owleye

bd-from-kg

Taffy Lewis :

It doesn’t matter.

My point can be stated more precisely as follows: The first premise is plausible only as a special case of the general principle that we should always refrain from believing falsehoods. Combining this with the second and third premises yields “If determinism is true, all beliefs are true”. But this is obviously false: there are possible worlds in which determinism is true and there are false beliefs. But if “can” is being used in the same sense in the second and third premise, this conclusion follows rigorously from these three premises. So either one of them is false, or “can” is not being used in the same sense in the second and third premises.

Now if “can” is being used in any reasonable sense other than that of having a nonzero probability, the third premise is false. (The term “reasonable” here is intended only to rule out definitions which bear no resemblance to the way “can” is normally used – e.g., “’X can do Y’ means ‘X is certain to do Y’”.) But if it is being used in this sense, the third premise is an immediate corollary of the definition of determinism, so one of the first two premises is false. Thus my statement (which assumed that the second premise is true) that in this case the first premise must be false.

For the record, here are some other meanings of “X can do Y” that have been proposed as “appropriate” in premise 2:

1. X would do Y if he chose to.
2. It is impossible to determine, from all of the information available in principle to anyone whatsoever, that X will not do Y.
3. There is some possible incentive structure (i.e., set of rewards and punishments) such that, if it were in place and X were aware of it, he would do Y.

[The point of the third meaning is that it relates the “should” in premise 2 to the “can” in the sense that if X can do Y in this sense, he can be induced to do it by putting such an incentive structure in place. For example, if it is considered desirable that X do Y, it would make sense to be prepared to blame him, or even punish him, if he fails do it, and to make sure that X is aware of this potential blame or punishment. I don’t say that this shows that this is the “correct” or “appropriate” meaning of “can” in premise 2; I’m just explaining why it’s on the list.]

All of these meanings are consistent with determinism. That is, with any of them it makes sense to say after the fact that X could have done Y even though he didn’t. But this means that premise 3 is false if “can” is interpreted in any of these ways.

I used “able” only to avoid grammatical awkwardness or possible misinterpretation. I could just as well have said “obviously there is not always a nonzero probability of refraining from believing a falsehood”. This is plainly so if determinism is true, and it seems to me to be clearly so even if it isn’t.

Are you always this nitpicky about the exact choice of words?

My quarrel here was with tronvillain’s proposed interpretation of “can” in premise 2. As I said, this is a side issue, and it now appears that tronvillain doesn’t disagree with me on this anyway.