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In the first half of the 17th century the Aristotelian view that the same statement or belief may be true at one time and false at another and, on the other hand, the conception of a mental proposition as a fully explicit thought that lends a definite meaning to a declarative sentence originated a lively debate concerning the question whether a mental proposition can change its truth-value.In this article it is shown that the defenders of a negative answer and the advocates of a positive answer argued on the basis of different notions of what a mental proposition is:one side taking it as more or less equivalent to a specific utterance?meaning and the other side as more or less equivalent to a generic sentence-meaning.

Summary Influenced by the account of K. Popper and, moreover, of C. G. Hempel and P. Oppenheim, it is generally assumed, that a prediction can be logically deduced from hypotheses, i. e. lawlike propositions, and initial conditions. It is not clear, in which respect a prediction can correctly be supposed to be a proposition which is either true or false. From a logical point of view, serious difficulties arise in assuming that the deductive-nomological model consists of a valid argument. Further objections to this account are developed with regard to lawlike propositions. Since a lawlike proposition is — by definition — not true or definitely true, but only supposed to be true, it cannot function as a true premise among other true premises for the purpose of deduction. Special difficulties arise with regard to predictions: A predictive argument does not give any reason for the truth of the predictionK, but only — if at all — for the prediction of the truth ofK. In the latter case, the conclusion K clearly does not consist of a proposition (which could be either true or false) but rather of a predicting proposition.

four ancestry, is that there are . A proposition may be true (and true only), false (and false only), both true and false, neither true nor false , ,.

The token in the box in this paper of a sentence does not express a proposition. Why not? Because if it did it would express a proposition that was, amongst other things, about this token of that sentence, and that thus said that it was not true. No proposition can say that of itself.

“To this day, partiality approaches to the paradox have been dogged by the so-called ‘Strengthened Liar’. .... The Strengthened Liar observes that if we follow a partiality theorist and declare the Liar sentence* neither true nor false (or failing to express a proposition,. or suffering from some sort of grave semantic defect), then the paradox is only pushed back. For we can go on to conclude that whatever this status may be, it implies that the Liar sentence is not true. This claim is true, but it is just the Liar sentence again.* We are back in paradox.” (Glanzberg 2002, p. 468, bold emphasis added.) Cf.: “We are back in our contradiction,”(Glanzberg 2001, p. 222). *The Liar sentence intended is evidently the sentence ‘the Liar sentence is not true’, and, the Liar sentence = ‘the Liar sentence is not true’. Cf.: “Consider a Liar sentence: ...let us take a sentence l which says l is not true. We can, informally, reason as..

Summary According to the Redundance Theory of Truth, the utterance it is true thatp means nothing more than simply ‘p’. So the utterance is true would be meaningless, redundant. The Redundance Theory overlooks that the the predicate true can be used in two applications: (a) as anassertion of the justness of a proposition, (b) as ajudgement of the justness of a proposition. (The word justness in this context means the correspondance of a proposition with reality according to the Theory of Correspondence.) The explicitassertion of the justness is indeed superfluous as it is implicitly included in the proposition. Thejudgement of the justness of a proposition, however, cannot be included in the proposition analytically. In this way, the utterance it is true thatp does not only mean ‘p’ but the assertion that is implicitly included in the proposition ‘p’ (= ‘p’ is true ) is true . Analogous: the utterance it is false that ‘p’ means the assertion that is implicitly included in the proposition ‘p’ (= ‘p’ is true ) is false . A judgement like this exceeds the content of a proposition and so cannot be redundant. Although in some context the words true and false may be used in their application an an assertion because of stylistic reasons, they are relevant for any theory of truth only in their application as a judgment, which cannot be contested by the reproach of redundance. The claim of the Redundance Theory that the concept of truth is meaningless and superfluous must be refused.

Probabilities range from 0 to 1. If a proposition has a probability of 0, then it’s certainly false; if 1, then it’s certainly true. A proposition with a probability of ½ (or 0.5, or 50%) is equally likely to be true as false, and a proposition with a probability of ¾ (or 0.75, or 75%) is three times as likely to be true as false.

Logic begins but does not end with the study of truth and falsity. Within truth there are the modes of truth, ways of being true: necessary truth and contingent truth. When a proposition is true, we may ask whether it could have been false. If so, then it is contingently true. If not, then it is necessarily true; it must be true; it could not have been false. Falsity has modes as well: a false proposition that could not have been true is impossible or necessarily false; one that could have been true is merely contingently false. The proposition that some humans are over seven feet tall is contingently true; the proposition that all humans over seven feet tall are over six feet tall is necessarily true; the proposition that some humans are over seven feet tall and under six feet tall is impossible, and the proposition that some humans are over nine feet tall is contingently false. Of these four modes of truth, let us focus on necessity, plus a fth: possibility. A proposition is possible if it is or could have been true; hence propositions that are either necessarily true, contingently true, or contingently false are possible. Notions that are similar to the modes of truth in being concerned with what might have been are called modal. Dispositions are modal notions, for example the disposition of fragility. Relatedly, there are counterfactual conditionals, for example “if this glass were dropped, it would break.” And the notion of supervenience is modal.1 But let us focus here on necessity and possibility. Modal words are notoriously ambiguous (or at least context-sensitive2). I may reply to an invitation to give a talk in England by saying “I can’t come; I have to give a talk in California the day before”. This use of “can’t” is perfectly appropriate. But it would be equally appropriate for me to say that I could cancel my talk in California (although that would be rude) and give the talk in England instead. What I cannot do is give both talks. But wait: it also seems appropriate to say, in another context, that given contemporary transportation..

Logic begins but does not end with the study of truth and falsity. Within truth there are the modes of truth, ways of being true: necessary truth and contingent truth. When a proposition is true, we may ask whether it could have been false. If so, then it is contingently true. If not, then it is necessarily true; it must be true; it could not have been false. Falsity has modes as well: a false proposition that could not have been true is impossible or necessarily false; one that could have been true is merely contingently false. The proposition that some humans are over seven feet tall is contingently true; the proposition that all humans over seven feet tall are over six feet tall is necessarily true; the proposition that some humans are over seven feet tall and under six feet tall is impossible, and the proposition that some humans are over nine feet tall is contingently false. Of these four modes of truth, let us focus on necessity, plus a fifth: possibility. A proposition is possible if it is or could have been true; hence propositions that are either necessarily true, contingently true, or contingently false are possible. Notions that are similar to the modes of truth in being concerned with what might have been are called modal. Dispositions are modal notions, for example the disposition of fragility. Relatedly, there are counterfactual conditionals, for example “if this glass were dropped, it would break.” And the notion of supervenience is modal.1 But let us focus here on necessity and possibility. Modal words are notoriously ambiguous (or at least context-sensitive2). I may reply to an invitation to give a talk in England by saying “I can’t come; I have to give a talk in California the day before”. This use of “can’t” is perfectly appropriate. But it would be equally appropriate for me to say that I could cancel my talk in California (although that would be rude) and give the talk in England instead. What I cannot do is give both talks..

Two quite different issues need to be addressed with regard to the sentence "God exists." One is whether or not the sentence expresses a proposition (something that is true or false and that can be believed or disbelieved). If we say, "Yes, it expresses a proposition," then the second issue comes in: Is that proposition true or false?[ 1].