Interlude: Possibility, Actuality, and Necessity Truth and Possibility Everything that is actual (or actually true) is possible (i.e. possibly true). We may ask an injured patient; "Can you (i.e. is it possible for you) to raise your arm?" If the patient then raises his arm, then that is proof-positive that it is possible for him to do so. (Note, however, if he does not raise his arm, that does not show that it is not possible for him to do so.) Thus: Actual truth is a sufficient condition for possible truth. (I.e. whatever is true is possible). And equivalently, Possible truth is a necessary condition for actual truth. (I.e. whatever is not possible is not actual). (Put still another way: Everything that is [actually] true is possibly true; but not everything that is possibly true is [actually] true.) Examples of possibly true propositions: New Westminster, BC, is north of Bellingham, Washington. Table salt dissolves in water. Pierre Trudeau was the first Canadian to travel in a space capsule. There are three times as many women in Canada as there are men. 2 + 2 = 4 All aunts are female. Some pigs can levitate. -------------------------------------------------------------------------------- Truth and Necessity A proposition is said to be 'necessarily true' (or 'logically true') if it is true under all possible circumstances. Examples of necessarily true propositions: 2 + 2 = 4 All aunts are female. Whatever is blue is colored. There are either fewer than 20 students in the room or there are more than 10. (This statement may be unobvious; but if you think about it you may come to see that it cannot be false.) It is false that some triangle has exactly four sides. Clearly, whatever is necessarily true is actually true. Necessary truth is a sufficient condition for actual truth. (I.e. what is necessarily true is actually true.) And equivalently, Actual truth is a necessary condition for necessary truth. (I.e. whatever is not actual is not necessary.) (Everything that is necessarily true is actually true; but not everything that is actually true is necessarily true.) In short, Necessary truth is a sufficient condition for actual truth. And Actual truth is a sufficient condition for possible truth. Finally, just to make life difficult: Necessary truth is not a necessary condition for actual truth. -------------------------------------------------------------------------------- "I might do A"; "I do A"; and "I must do A" When we consider the actions we take and the choices we make, we conceive of them as falling into three categories: (1) what we might do (i.e. that which is possible); (2) what we actually do; and (3) what we must (or have to) do (i.e. that which could not be otherwise). Possible Actual Necessary (note: the table below is much easier read on the site: http://www.sfu.ca/philosophy/swartz/freewill2.htm) Past "I could have done A." "It was possible for me to have done A." "I did A." "I had to do A." Present "I could do A (now)." "I might do A (now)." "It is possible for me to do A (now)." "I do A (now)." "I am doing A (now)." "I have to do A (now)." "I must do A (now)." "I cannot do otherwise than A (now)." Future "I might do A (in the future)." "I can do A (in the future)." "It will be possible for me to do A." "I will do A (in the future)." "I will have to do A (in the future)." "I must do A (in the future)." "I will not be able to do otherwise than A (in the future)."
Epistemic Determinism (Resumption of discussion, following Interlude) Terms such as (i) "possible", "may", "can", "could" (which signify possibility) and terms such as (ii) "must", "has to", "necessarily", "could not [or do] otherwise" (which signify necessity) are said to be modal terms. We will, for convenience, call the former class - those that signify possibility - "weak modal terms", and we will call the latter class - those that signify necessity - "strong modal terms". In English (and in a great many other natural languages as well), it is common to express the relationship of necessary condition using a strong modal term (underlined in these examples) in the consequent of an if-then sentence. "If Paul has two sons and a daughter, then he has to have at least two children." "If you have pneumonia, then you have to have fluid in at least one of your lungs." "If you have a fever, then your internal body temperature must be greater than normal." Now, each of the preceding, as ordinarily understood, is true. But they are misleading. They are stated in such a manner as to conceal, and indeed distort, their 'internal logic' (so to speak). Let's look at the first of these: "If Paul has two sons and a daughter, then he has to have at least two children." The antecedent of this sentence expresses a true proposition. (Paul is my brother and he does have two sons and a daughter.) Thus according to the valid inference rule (known as "Modus Ponens") which allows us to infer the consequent of any true conditional statement whose antecedent is true, we should be able to infer: "Paul has to have at least two children." Something is clearly amiss. While it is true that Paul does (in fact) have at least two children (he has three), it is false that he has to have three. He doesn't have to have any. He doesn't have to have one. He doesn't have to have two. He doesn't have to have three. He doesn't have to have four. Etc., etc. Put another way: There is no necessity in Paul's having any children, let alone having three. There is no necessity for Paul (just as there is no necessity for anyone else) to have at least two children. There is something, then, seriously in error in the following argument (or inference): If Paul has two sons and a daughter, then he has to have at least two children. Paul has two sons and a daughter. -------------------------------------------------------------------------------- Paul has to have at least two children. The source of the logical error lies (as suggested above) in placing the strong modal term in the consequent, where it appears to 'modify' that proposition (the 'then-clause'). However, the logical role of the strong modal term is to modify the relationship between the antecedent (the 'if-clause') and the consequent (the 'then-clause'); its role is not to modify the consequent alone. Although the following sentences are not especially idiomatic (stylish), they do at least reveal, far better than the preceding three sentences, the correct underlying logic of the claims being made. "It has to be that (if Paul has two sons and a daughter, then he has at least two children)." "It has to be that (if you have pneumonia, then you have fluid in at least one of your lungs)." "It must be that (if you have a fever, then your internal body temperature is greater than normal)." I am not suggesting that we reform our sentences and learn to speak in this latter, stilted, fashion. What I am suggesting is that when we utter sentences of the form "If so-and-so, then it must be that such-and-such", we understand their underlying logic (in most cases) to be: "It must be that (if so-and-so, then it is such-and-such)." Finally, we can apply these several logical niceties to the problem of Epistemic Determinism. Let's recall the argument that initiated this current discussion: ORIGINAL Version of the Argument for Epistemic Determinism Premise 1 - If x knows that you are going to do [some action] A, then you must do A. Premise 2 - But if you must do A, then you have no choice in the matter (i.e. you will not be able to do otherwise than A). -------------------------------------------------------------------------------- Thus - If x knows (beforehand) that you are going to do A, then you have no free choice (i.e. you will not be able to do otherwise than A). Or, put another way: Foreknowledge is incompatible with free will. As should now be clear, the first premise - because of the way we ordinarily state necessary conditions - appears to be true. But if taken literally, at face value, as is being done in this argument, the first premise is false. If, however, we take some care to express the first premise in a non-misleading way, so that it expresses correctly the underlying logic, then the conclusion above does not follow from the (corrected) premises. CORRECTED Version of the Argument for Epistemic Determinism Premise 1 - It must be that (if x knows that you are going to do [some action] A, then you will do A). Premise 2 - But if you must do A, then you have no choice in the matter. -------------------------------------------------------------------------------- Thus - If x knows (beforehand) that you are going to do A, then you will do A. The supposed problem - that foreknowledge is incompatible with free will - disappears once the logic of the fallacious argument is corrected. Concluding remarks about epistemic determinism The notion that foreknowledge, and in particular God's foreknowledge, is incompatible with free will is not a mere semantic trifle. It is not just word-chopping. For some persons, believing that God's foreknowledge is incompatible with free will has had, and for some persons will have, a profound affect on their lives. Some persons who believe that there is an omniscient (i.e. all-knowing) God have accepted the fallacious argument which we have been reviewing, and not knowing that it is fallacious, have come to believe that they have no free will. Others, also being beguiled by the argument, have - in believing that they do have free will - rejected the idea that there can be an omniscient God. In both cases, these persons might have lived, or would live, rather different lives if they were to see that they have fallen victim to a subtle logical confusion. Sometimes logical errors do have the most profound, indeed lifelong, consequences for persons who do not perceive those errors. Foreknowledge no more 'forces' the future to be a certain way, than true reports in history books 'force' the past to have been a certain way. Copyright © Norman Swartz 1997 URL http://www.sfu.ca/philosophy/swartz/freewill3.htm November 9, 1997 Department of Philosophy Simon Fraser University
thanks for the post, tripack. nice work, keep it coming ! i would like to see some more "heavy" reasoning concerning the creator and less of the dogmatic circular statements from the athiests and believers. it is quite apparent to me that dan, although extremely intelligent, has a profound hatred/mistrust of all things outside of the "scientific method". why ??? who knows. best, surF
holy smokes! and atheists are the ones accused of playing semantic games! 1. X is a possible scenario 2. X is caused by caused certain actions (A) 3. certain actions (B) deny the possibility of X 4. other actions (C) are possible that do not include all or part of (A) or (B) 5. free will (F) is the choice of either (A) or (B) or (C) it is infallibly known that X will happen, therefore (B) cannot be taken therefore (F) is denied
dan, take a look at www.irr.org/schaefer1.html , in addition the book "signs of intelligence" lays a fairly cogent argument for a creator. if you can reason against this material, i would like to hear it. best, surf
in addition, another book that stimulated my thinking is "darwin's black box" it casts grave doubts on the atheists idol's theory. read it, if you dare... surf, the dogmacat
Give it up Tri-pack, et al. Arguing with Dan is like arguing with a mongoloid retard. No matter how compelling or logical your argument, he just can't comprehend it. It's not worth the effort.
You can call the logical proof provided "semantic games" but it is a serious logical proof. If you can find a flaw in its reasoning, I encourage you to state that flaw. It shows in a logical manner why the conclusion that omniscience cannot coexist with free will that keeps getting restated in various ways flows from flawed logic, and is therefore a false conclusion. Looking at the proof you provide, and accepting all the premeses at face value I can see that the conclusion you draw doesn't in fact flow from the premeses. You can say It is infallibly known that X will happen, therefore the choice will be A. However, your own definition of free choice F is that either A, B or C will be chosen. A is chosen therefore F exists. If you remove A as a choice then your definition of free will precludes one of the options which makes free will not exist.
your website diatribe is not logical proof. you just wish it was. it means exactly the same thing as the proposition it tries to correct. i'll explain that later, i can't be bothered right now. whatsmore, i detest the incredible hypocrisy here. you are all too willing to accept logical proof when it supports your position, but none too willing to accept it when it negates it. if you think the impossibility of co-existance of omniscience and free will is the only logic based charge against your position, you are sorely mistaken. EVEN IF, in the extreme unlikelihood that i am mistaken on the charge of impossibility of omniscience, there are many other logical proofs against your god. would you be willing to accept those as logical proofs against your position? something in my gut tells me no way. in defence of (5): (B) and (C) were NEVER possible choices, because X had to happen. good luck.