3 cases of acute transverse syndrome caused by a dissecting aneurysm of the aorta

A relatively rare cause of the acuto transverse syndrome, aneurysma dissecans of the aorta followed by disturbance of the circulation in the spinal cord, is described on the basis of three cases. The special features of the blood supply of the spinal cord and the etiopathogenesis, symptomatology and prognosis of aneurysma dissecans are discussed. Attention is drawn to the necessity of unobtrusive methods for case taking and clinical examination to save the patient unnecessary stress and to improve the chances of survival.     

A Posteriori Necessity as Restricted Necessity

I argue that conventionalists should construe a posteriori necessity as restricted necessity. I take Sidelle’s defence of the conventionalist explanation of a posteriori necessity against the contingency problem as the starting point. Sidelle construes a posteriori necessity as unrestricted necessity and then argues that a posteriori necessity is to be considered under a fixed convention (meaning) and is thus irrelevant to the contingent nature of our linguistic conventions. I offer a different solution to the contingency problem. I argue that conventionalists should construe a posteriori necessity as restricted necessity based upon a use-based meta-semantic picture. Restricted necessity is contingent in a broader sense and does not conflict with the contingency of conventions. My solution allows conventionalists to explain a posteriori necessity as restricted necessity. I show that the realist’s arguments for a posteriori necessity are unconvincing in regard to real modal features and a posteriori necessity as unrestricted necessity. We thus have good reason to continue to accept a posteriori necessity as restricted necessity under the conventionalist explanation.

     

要重视慢性乙型肝炎的抗病毒治疗

慢性乙型肝炎是我国常见的慢性传染病之一,严重危害人民健康.围绕着乙型肝炎的防治,带来巨大的经济负担,已成为不可忽视的社会问题.在慢性乙型肝炎-肝硬化-HCC的发生发展过程中,HBV病毒载量起着重要的作用,抗病毒治疗是目前治疗慢性乙型肝炎的有效手段.因此,要重视和规范抗病毒治疗.     

Possible Ideas of Necessity in Indian Logic

It is often remarked that Indian logic (IL) has no conception of necessity. But what kind of necessity is absent in this system? Logical necessity is presumably absent: the structure of the logical argument in IL is often given as a reason for this claim. However even a cursory understanding of IL illustrates an abiding attempt to formulate the idea of necessity. In Dharmakīrti's classification of inferences, one can detect the formal process of entailment in the inferences arising from class inclusion. In Western philosophy, Leibniz's invocation of 'contingent necessity' as distinguished from the 'necessary necessity' is part of a tradition that finds value in the idea of contingent necessity. In contemporary philosophy, this has been championed by Armstrong, specifically in the context of understanding the necessity inherent in scientific laws. In IL, the analysis of 'invariable concomitance' (vyāpti) is of crucial importance and its definitions are very complex. This paper argues how vyāpti can be understood in terms of contingent necessity and also how the complex definitions can be interpreted as an attempt to define contingent necessity in terms of 'logical' necessity.     

Aristotle on a Puzzle about Logical Consequence: Necessity of Being vs. Necessity of Saying

In the Posterior Analytics (I 6, 75a18–27) Aristotle discusses a puzzle which endangers the possibility of inferring a non-necessary conclusion. His solution relies on the distinction between the necessity of the conclusion's being the case and the necessity of admitting the conclusion once one has admitted the premisses. The former is a factual necessity, whereas the latter is meant to be a normative or deontic necessity that is independent of the facts stated by the premisses and the conclusion. This paper maintains that Aristotle resorts to this distinction because he thinks that, as long as it is conceived as a factual relation, logical consequence cannot exist independently of the facts expressed by the premisses and the conclusion. As a corollary, the necessity of such a consequence relation always requires the necessity of these facts. Aristotle holds this factual conception of logical consequence responsible for the puzzle, since it cannot account for valid syllogisms with contingent or false premisses. The alternative conception of necessity is then introduced by him in order to make good this deficiency. The distinction between the necessity of being and the necessity of saying was revived by the Oxford logician E. W. B. Joseph, and taken over by Frank Ramsey in his seminal Truth and Probability, but has not received attention from recent interpreters of Aristotle's logic. This paper, however, argues that, in spite of its intrinsic interest, the distinction bore no significant fruit in Aristotle's logical doctrine.     

The Broadest Necessity

In this paper the logic of broad necessity is explored. Definitions of what it means for one modality to be broader than another are formulated, and it is proven, in the context of higher-order logic, that there is a broadest necessity, settling one of the central questions of this investigation. It is shown, moreover, that it is possible to give a reductive analysis of this necessity in extensional language (using truth functional connectives and quantifiers). This relates more generally to a conjecture that it is not possible to define intensional connectives from extensional notions. This conjecture is formulated precisely in higher-order logic, and concrete cases in which it fails are examined. The paper ends with a discussion of the logic of broad necessity. It is shown that the logic of broad necessity is a normal modal logic between S4 and Triv, and that it is consistent with a natural axiomatic system of higher-order logic that it is exactly S4. Some philosophical reasons to think that the logic of broad necessity does not include the S5 principle are given.     

Necessity and sufficiency in abstract conditional reasoning

The necessity and sufficiency of the cause relates to the conclusions people draw on everyday conditional inference problems. The current research explores the effects of necessity and sufficiency in an abstract causal context. Three experiments showed that the subjective ratings of necessity and sufficiency diverge from the objective levels: A sufficient and necessary cause is more often labelled as sufficient than a sufficient and not-necessary cause. Likewise, a necessary and sufficient cause is more often labelled necessary than a necessary and not-sufficient cause. In Experiments 1 and 2 we observed that the robust effects of sufficiency on MP and MT, and of necessity on AC and DA found on everyday reasoning generalise to abstract conditionals. There were also partial effects of sufficiency on AC and DA, and of necessity on MP and MT. When the problem presentation is simplified, as in Experiment 3, these partial effects on reasoning disappear. The reasoning results then relate to the objective levels and less to the subjective levels of necessity and sufficiency. This divergence sheds doubt on the idea that reasoners base their inferences on an active assessment of the necessity and/or sufficiency of the causal relation.     

How many notions of necessity?

Evans distinguishes between superficial necessity and deep necessity in his analysis of the contingent a priori. The distinction between these two notions of necessity is formalized by Davies and Humberstone through the addition of the operator Fixedly to Actuality Modal Logic (AML, S5A), where deep necessity is represented by the combination Fixedly Actually. Wehmeier’s Subjunctive Modal Logic (SML) provides an extension of the expressive capacity of ordinary modal predicate logic alternative to AML. I add Fixedly to SML and show that in the system SML with Fixedly the distinction between deep and superficial necessity disappears. I conclude that the existence of the distinction between deep and superficial necessity, as well as the existence of the contingent a priori, cannot be asserted independently of the choice of background logic.     

Kant's Criteria of the A Priori

Kant states that necessity and strict universality are criteria of a priori knowledge. Interpreting this dictum standardly and straightforwardly in respect of necessity, it is inconsistent with there being necessary a posteriori truths or contingent a priori truths (cf Kripke). This straightforward interpretation may convict Kant of understandable error (at worst) in the case of necessity, but it is so uncharitable in the case of strict universality that we ought to seek an alternative. I offer a charitable interpretation of the doctrine that necessity and strict universality are sufficient conditions of a priority, commenting briefly on comparable necessary conditions.     

How We Hurt The Ones We Love

Paradoxically, the practical necessity of love seems to combine the personal character of psychological necessity with the inescapable and authoritative quality of moral necessity. Traditionally, philosophers have avoided this paradox by treating love as an amalgam of impersonal evaluative judgments and affective responses. On my account, love participates in a different form of practical necessity, one characterized by a non‐moral yet normative type of expectation. This expectation is best understood as a kind of second‐personal address that does not support derivative third‐personal demands. It is revealed when we react with hurt feelings instead of resentment upon its disappointment.     

Plato on Necessity and Disorder

In the Timaeus, Plato makes a distinction between reason and necessity. This distinction is often accounted for as a distinction between two types of causation： purpose oriented causation and mechanistic causation. While reason is associated with the soul and taken to bring about its effects with the good and the beautiful as the end, necessity is understood in terms of a set of natural laws pertaining to material things. In this paper I shall suggest that there are reasons to reconsider the latter part of this account and argue for a non-mechanistic understanding of necessity. I will first outline how the notion of necessity is introduced in the dialogue. Next I will show how a mechanistic account of necessity fails to capture Plato＇s purpose of treating it as a causal factor; and, finally, I will argue that this purpose is better understood as an attempt, on Plato＇s part, to account for the causal origin of disorder and irrationality, an origin articulated in terms of a pre-cosmic situation and the notoriously difficult notion of the third kind.     

On the Reduction of Necessity to Essence

In his influential paper ‘‘Essence and Modality’’, Kit Fine argues that no account of essence framed in terms of metaphysical necessity is possible, and that it is rather metaphysical necessity which is to be understood in terms of essence. On his account, the concept of essence is primitive, and for a proposition to be metaphysically necessary is for it to be true in virtue of the nature of all things. Fine also proposes a reduction of conceptual and logical necessity in the same vein: a conceptual necessity is a proposition true in virtue of the nature of all concepts, and a logical necessity a proposition true in virtue of the nature of all logical concepts. I argue that the plausibility of Fine's view crucially requires that certain apparent explanatory links between essentialist facts be admitted and accounted for, and I make a suggestion about how this can be done. I then argue against the reductions of conceptual and logical necessity proposed by Fine and suggest alternative reductions, which remain nevertheless Finean in spirit.     

Essence and Necessity

Journal of Philosophical Logic - What is the relation between metaphysical necessity and essence? This paper defends the view that the relation is one of identity: metaphysical necessity is a...     

Causal Necessity in Aristotle

Like many realists about causation and causal powers, Aristotle uses the language of necessity when discussing causation, and he appears to think that by invoking necessity, he is clarifying the manner in which causes bring about or determine their effects. In so doing, he would appear to run afoul of Humean criticisms of the notion of a necessary connection between cause and effect. The claim that causes necessitate their effects may be understood— or attacked— in several ways, however, and so whether the view or its criticism is tenable depends on how we understand the necessitation claim. In fact, Aristotelian efficient causation may be said to involve two distinct necessary connections: one is a relation between causes considered as potential, while the other relates them considered as active. That is, the claims that (1) what has the power to heat necessarily heats what has the power to be heated, and that (2) a particular flame which is actually under a pot necessarily heats it, both of which appear to be true for Aristotle, involve distinct notions of necessity. The latter kind of necessity is based on the facts, as Aristotle sees them, about change, whereas the former is based in the nature of properties. Though different, both kinds of necessity are instances of what contemporary philosophers would call metaphysical necessity, and together they also amount to a theory of causal determination.     

The Varieties of (Relative) Modality

In ‘The Varieties of Necessity’ Fine presents purported counterexamples to the view that a proposition is a naturally necessary truth if and only if it is logically necessary relative to or conditional upon the basic truths about the status and distribution of natural kinds, properties and relations. The aim of this article is to defend the view that natural necessity is relative necessity, and the general idea that we can define other kinds of necessity as relative, against Fine's criticisms.     

Laws: Projectability and uniformity

It is argued that the problem of the necessity and projectability of laws may be solved by distinguishing between the fact of necessity and explanations of its nature. This reduces the problem of necessity to that of induction, which in consequences must be solved without reference to necessity using ‘self‐supporting’ arguments. The consequences for the analysis of ‘counterfactual conditionals and the problem of language dependence is discussed.     

On Categories and A Posteriori Necessity: A Phenomenological Echo

This article argues for two related theses. First, it defends a general thesis: any kind of necessity, including metaphysical necessity, can only be known a priori. Second, however, it also argues that the sort of a priori involved in modal metaphysical knowledge is not related to imagination or any sort of so‐called epistemic possibility. Imagination is neither a proof of possibility nor a limit to necessity. Rather, modal metaphysical knowledge is built on intuition of philosophical categories and the structures they form.     

Manifesting belief in absolute necessity

McFetridge (in Logical necessity and other essays. London: Blackwell, 1990) suggests that to treat a proposition as logically necessary—to believe a proposition logically necessary, and to manifest that belief—is a matter of preparedness to deploy that proposition as a premise in reasoning from any supposition. We consider whether a suggestion in that spirit can be generalized to cover all cases of absolute necessity, both logical and non-logical, and we conclude that it can. In Sect. 2, we explain the significance that such an account of manifestation of belief in absolute necessity has for the prospects of a non-realist theory of modality. In Sect. 3, we offer a sympathetic articulation of the detail that underlies the McFetridge conception of belief in logical necessity. In Sects. 4 and 5, we show that the conception so articulated will not generalize to encompass all cases of belief in absolute necessity and proceed to offer a remedy. Our proposal is based upon a distinction between two kinds of suppositional act: A-supposing and C-supposing (Sect. 6). In Sect. 7, we then explain and defend our central thesis: (roughly) that (manifestation of) belief in absolute necessity is a matter of preparedness to deploy as a premise in reasoning under any C-supposition. Finally, we indicate that there is some promise in the parallel thesis that manifestation of the treatment of a proposition as a priori is a matter of preparedness to deploy as a premise in reasoning under any A-supposition (Sect. 8).     

Did Kant Conflate the Necessary and the A Priori?

It is commonly accepted by Kant scholars that Kant held that all necessary truths are a priori, and all a priori knowledge is knowledge of necessary truths. Against the prevailing interpretation, I argue that Kant was agnostic as to whether necessity and a priority are co‐extensive. I focus on three kinds of modality Kant implicitly distinguishes: formal possibility and necessity, empirical possibility and necessity, and noumenal possibility and necessity. Formal possibility is compatibility with the forms of experience; empirical possibility is compatibility with the causal powers of empirical objects; noumenal possibility is compatibility with the causal powers of things in themselves. Because we cannot know the causal powers of things in themselves, we cannot know what is noumenally necessary and what is noumenally contingent. Consequently, we cannot know whether noumenal necessity is co‐extensive with a priority. Therefore, for all we know, some a priori propositions are noumenally contingent, and some a posteriori propositions are noumenally necessary. Thus, contrary to the received interpretation, Kant distinguishes epistemological from metaphysical modality.     

Supervenience and causal necessity

Causal necessity typically receives only oblique attention. Causal relations, laws of nature, counterfactual conditionals, or dispositions are usually the immediate subject(s) of interest. All of these, however, have a common feature. In some way, they involve the causal modality, some form of natural or physical necessity. In this paper, causal necessity is discussed with the purpose of determining whether a completely general empiricist theory can account for the causal in terms of the noncausal. Based on an examination of causal relations, laws of nature, counterfactual conditionals, and dispositions, it is argued that no reductive program devoid of essentialist commitments can account for all the phenomena that involve causal necessity. Hence, neo-Humean empiricism fails to provide a framework adequate for understanding causal necessity.I am grateful to D. M. Armstrong, Ellery Eels, Kit Fine, Philip Quinn, Elliot Sober, Chris Swoyer, Bas van Fraassen, and an anonymous Synthese referee for helpful comments on an earlier draft of this paper.