Abstract
In 11.13 I have taken the view that normative judgements cannot be derived from factual judgements. It has been remarked (in II.8) that this means it is ‘no longer self-evident that logic presents a possibility for normative reasoning’. This is connected with the fact that, if normative judgements cannot be derived from factual judgements, it is no longer self-evident that those normative judgements can be either true of false.
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Notes
Finnis, 1980, p.33 ff.
Finnis, 1980, p.69.
Jørgensen, 1938, p.183–190; 1937/38, p.288–296.
Jørgensen, 1937/38, p.288.
Jørgensen, 1937/38, p.289.
Jørgensen, 1937/38, p.290.
Ross, 1941, p.59.
Ross, 1941, p.69.
Ross, 1941, p.69.
Ross, 1968, p.170. In this work Ross attempts to solve the problem by already omitting the logical values ‘true’ and ‘false’ in indicative logic and replacing them by ‘a higher order concept’ which would then have to be used in an alethic as well as in a deontic context. This ‘higher order concept’, predicates whether (deontic or alethic) speech can have meaning (by not being tautologous or self-contradictory) or not (cf. p.177–182). This solution is, however, not succesful because of the fact that Ross’ ‘higher order concept’ presupposes a ‘lower order concept’. By the possibility to have meaning Ross in fact means that the judgement concerned can be true or false (or, in the case of a directive, valid or invalid); no possibility of having meaning exists if, for reasons of logic, the judgement can be only true (valid) or only false (invalid). Ross’ higher order concept cannot take the place of the logical values, because of the fact that both positive logical values (true, valid) and negative logical values (false, invalid) can be assigned to contingent judgements. With the establishment of his deontic logic Ross does in fact not apply the higher order concept, but this lower order concept. Cf. e.g. the table which is rendered in section VI.5 below.
Von Wright, 1963, p.120–125.
‘The contradiction between an obligation to keep to all one’s promises and the prohibition to keep to a particular promise cannot be expressed by means of the proposition-calculus’ instrumentary; the contradiction between the obligation to keep to a promise and the absence of this obligation can be expressed in the proposition-calculus, but does not present any difficulties with Von Wright’s reduction of the existence of normative judgements to their being willed.
Von Wright, 1963, p.148.
Von Wright, 1963, p.151. Von Wright has discussed this problem in other publications as well. In 1981, p.408 e.g. he asks the question: ‘can there not exist “contradiction” in the law?’ Von Wright’s 1981 answer to this question is, in my opinion, the same as the answer he gave in 1963. This time he uses a kind of Andersonian reduction: the notion of an obligation is related ‘to that of a necessary requirement for something which can, in a broad sense, be characterized as an end’ (say: the avoidance of a sanction). It seems reasonable that a condition for such a requirement would be ‘that the end is something, which one can secure’ (p.408) (the Andersonian axiom ◊ -S). In my opinion everyone will agree with the reasonableness of this condition. Nevertheless, neither logic nor anything else compels the norm-authorities to keep to this standard. In fact, norm-authorities sometimes do promulgate conflicting norms, as it is known by everyone. If one, as Von Wright in 1981, favours a descriptive interpretation of deontic logic (being a logic of normative statements) then there is at least some problem concerning the relevance of standards of reasonableness for deontic logic. See also Von Wright, 1985, which, because of this reason, denies the possibility of a logic of norms.
Von Wright, 1963, p.151.
G.H. von Wright, 1985, p.268 ff.
1985, p.269, 270
1985, p.271
1985, p.272, referring to J. Hintikka, e.g. 1971
1985, p.272
The latter is completely parallel to alethic logic, the first is not: the inference of a logically valid alethic reasoning is necessarily true if the premisses are true. In the next part of this section I will attempt to give a description of the values ‘valid’ and ‘invalid’ in such way that the parallel with alethic logic is once again rendered complete.
H. Kelsen, 1974; H. Kelsen, 1979. References in the text are to the latter work. The quotations have been translated by us.
These are not all the arguments which are brought forward by Kelsen. He e.g. also states that the general norm, unlike the individual norm is conditional (p.186), but the relevance of
this statement (given its truth) is not clear. The arguments which are stated in the text are, in my opinion, the most relevant for Kelsen.
Although the current systems of deontic logic are modal, this is not necessarily so. The proposition-calculus e.g. can be interpreted as a deontic logic as well, though in such a system far less can be expressed than in a modal deontic system (in the same way as less can be expressed in the alethic proposition-calculus than in the alethic modal logic).
Particularly for non-logicians, I wish to point to the fact that e.g. completeness does not mean that all normative reasonings which we intuitively, and possibly rightly, experience as being logically valid, have to be logically valid according to the system. It is e.g. possible, as it was indicated in the foregoing note, to interpret the proposition-calculus deontically by agreeing that p, q, r,... will be interpreted by normative judgements. According to all formal systems known to me which have been developed in literature it is valid that: if a is obligatory it follows that -a is prohibited. However, based only on the proposition-calculus this is not logically valid. For in the language of the proposition-calculus we would have to formulate this argument as: if p, then it follows that q, which of course cannot be proven. This does not mean, however, that the proposition-calculus is incomplete as a deontic logic. For it is de facto possible, e.g. according to a formal-legal standard for validity, that ‘a is obligatory’ is valid while at the same time ‘-a is prohibited’ is invalid. In that case the first judgement will also be valid and the second invalid according to the rules which were formulated in the foregoing section (in this case, by ‘formal system’ in section 8 the system of the proposition-calculus is meant). The same occurs in an alethic context: ‘if p is necessary, then p is not impossible’, which is intuitively and according to modal alethic logic logically valid, is, however, not valid within the system of the proposition-calculus, which does not, by any means, infringe the completeness of the latter.
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Soeteman, A. (1989). The Possibility of Deontic Logic. In: Logic in Law. Law and Philosophy Library, vol 6. Springer, Dordrecht. https://doi.org/10.1007/978-94-015-7821-9_3
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