Do incompatibilist arguments, like some fatalist arguments, rest on modal fallacies? If Westphal (2012) is right, then one popular argument for incompatibilism van Inwagen’s “First Formal Argument” does rest on a modal fallacy. Similarly, Warfield (2000) claims that the standard modal formulation of the master argument for incompatibilism is a modal fallacy. Here, I refute both claims. Contra Westphal, I show that the mistake in van Inwagen’s "First Formal Argument" is no modal fallacy. After (...) that, I argue that Warfield’s charge of modal fallacy can be easily avoided by using a plausible principle concerning actuality. Then, I show that this allows one to put forward a fairly simple argument for fatalism (the thesis that we aren’t able to do otherwise from what we actually do). (shrink)

In his great poem, Parmenides uses an argument by elimination to select the correct "way of inquiry" from a pool of two, the ways of is and of is not , joined later by a third, "mixed" way of is and is not . Parmenides' first two ways are soon given modal upgrades - is becomes cannot not be , and is not becomes necessarily is not (B2, 3-6) - and these are no longer contradictories of one another. And (...) is the common view right, that Parmenides rejects the "mixed" way because it is a contradiction? I argue that the modal upgrades are the product of an illicit modal shift. This same shift, built into two Exclusion Arguments, gives Parmenides a novel argument to show that the "mixed" way fails. Given the independent failure of the way of is not , Parmenides' argument by elimination is complete. (shrink)

1. Anderson and Belnap's most explicit characterization of the fallacy of modality is as follows: "Modal fallacies arise when it is claimed that entailments follow from, or are entailed by, contingent propositions." The view which Nelson attributes to Anderson and Belnap, on the other hand, is "that necessary propositions are entailed only by necessary ones, never by contingent ones." Anderson and Belnap speak of "entailments," whereas Nelson generalizes to "necessary propostitions." The move is far from innocent, as we (...) shall see. For though Anderson and Belnap hold that every true entailment is a necessary proposition, not every necessary proposition is an entailment. In order to grasp the implications of this distinction more clearly, let us see how Anderson and Belnap's statement of the modal fallacy might legitimately be restated in terms of necessity. To that end we must draw a related distinction between necessary propositions and necessity propositions. A expresses a necessary proposition iff A → A → A holds. A expresses a necessity proposition iff A is of the form B → C. The particular form of these definitions is dependent on the fact that entailment rather than necessity is primitive in Anderson and Belnap's system; the forms in parentheses are the equivalents in terms of necessity. Now it follows from these definitions that every entailment is a necessity proposition and that every necessity proposition is an entailment. The modal fallacy may thus be equivalently characterized as the claim that a necessity proposition is entailed by a contingent proposition. That this is different from Nelson's formulation is clear from the following considerations. First, not every necessary proposition is a necessity proposition; example: "Either it is raining or it is not raining." Second, not every necessity proposition is a necessary proposition; example: any false necessity proposition. Thus the possibility is left open that some necessary proposition might be entailed by a contingent one. This is exactly the case with Nelson's example 2, "That every polychromatic surface is red entails that every polychromatic surface is colored." This might well be a theorem in a suitable extension of E. Such cases do not, however, arise among the theorems of EI. In that limited system, all that a contingent proposition can entail is itself. (shrink)

Note: the technical vocabulary used in this article is explained in a glossary that I prepared for my introductory logic course in 1997.

I critically examine the claim that modal collapse arguments against the traditional doctrine of divine simplicity (DDS) are in general fallacious. In a recent paper, Christopher Tomaszewski alleges that modal collapse arguments against DDS are invalid, owing to illicit substitutions of nonrigid singular terms into intensional contexts. I show that this is not, in general, the case. I show, further, that where existing modal collapse arguments are vulnerable to this charge the arguments can be repaired without any (...) apparent dialectical impropriety. I conclude that the genuine debate over modal collapse and divine simplicity and modal collapse is substantially a controversy over the metaphysics of divine action, and that this constitutes a fruitful direction in which to take future discussions of the subject. (shrink)

The argument given by Peter van Inwagen for the second premise on his "First Formal Argument" in An Essay on Free Will is invalid. The second premise hinges on the principle that since a proposition p , some statement about the present, is actually true, ~p can't be true. ~p must be false. What is the reason? The principle is that ~p cannot be true at the same time as p . I argue that, among other things, in its attachment (...) to this sort of principle, van Inwagen's argument commits the most familiar of all the modal scope fallacies. (shrink)

This is a book about the concept of a physical thing and about how the names of things relate to the things they name. It questions the prevalent view that names 'refer to' or 'denote' the things they name. Instead it presents a new theory of proper names, according to which names express certain special properties that the things they name exhibit. This theory leads to some important conclusions about whether things have any of their properties as a matter of (...) necessity. This will be an important book for philosophers in metaphysics and the philosophy of language, though it will also interest linguists concerned with the semantics of natural language. (shrink)

This is a book about the concept of a physical thing and about how the names of things relate to the things they name. It questions the prevalent view that names 'refer to' or 'denote' the things they name. Instead it presents a new theory of proper names, according to which names express certain special properties that the things they name exhibit. This theory leads to some important conclusions about whether things have any of their properties as a matter of (...) necessity. This will be an important book for philosophers in metaphysics and the philosophy of language, though it will also interest linguists concerned with the semantics of natural language. (shrink)

This study in fundamental ontology calls for rethinking some pedestrian assumptions about what there is and provides the motivation for a new theory of reference. It contains clear, crisp discussions of mereology, identity, reference, and necessity and should be valuable to metaphysicians and philosophers of language.

In John Etchemendy's book, The Concept of Logical Consequence, several arguments are put forth against the standard model‐theoretic account of logical consequence and logical truth. I argue in this article that crucial parts of Etchemendy's attack depend on a failure to distinguish two senses of logic and two correlative senses of being something a logical question. According to one of these senses, the logic of a language, L, is the set of logical truths of L. In the other sense, logic (...) is a theoretical discipline whose aim is to characterize logical properties and it can be identified with the set of sentences on what, and why, the extension of the set of logical truths of a particular language is. Some particular claims by Etchemendy about the status assigned to the axiom of infinity in the model‐theoretic account are criticized and shown to be erroneous because of that conflation. (shrink)

In John Etchemendy's book, The Concept of Logical Consequence, several arguments are put forth against the standard model‐theoretic account of logical consequence and logical truth. I argue in this article that crucial parts of Etchemendy's attack depend on a failure to distinguish two senses of logic and two correlative senses of being something a logical question. According to one of these senses, the logic of a language, L, is the set of logical truths of L. In the other sense, logic (...) is a theoretical discipline whose aim is to characterize logical properties and it can be identified with the set of sentences on what, and why, the extension of the set of logical truths of a particular language is. Some particular claims by Etchemendy about the status assigned to the axiom of infinity in the model‐theoretic account are criticized and shown to be erroneous because of that conflation. (shrink)

Michael Jubien’s Ontology, Modality, and the Fallacy of Reference is an interesting and lively discussion of those three topics. In ontology, Jubien defends, to a first approximation, a Quinean conception: a world of objects that may be arbitrarily sliced or summed. Slicing yields temporal parts; summing yields aggregates, or fusions. Jubien is very unQuinean in his explicit Platonism regarding properties and propositions, but concerns about abstracta are peripheral to much of the argumentation in the book.1 His version of the doctrine (...) that arbitrary mereological sums exist is nonstandard in that he views it as a convention (albeit a useful one) that we treat sums of objects as themselves being objects. Indeed, he views the concept of objecthood itself as being conventional. The world consists fundamentally of stuff, which we divide into things in any way that suits our purposes. In modality, Jubien’s views are to a first approximation Chisholmian: he holds the doctrine of mereological essentialism, according to which anything.. (shrink)

In this paper I will attempt a unified analysis of the various examples of the fallacy of accident given by Aristotle in the Sophistical Refutations. In many cases the examples underdetermine the fallacy and it is not trivial to identify the fallacy committed. To make this identification we have to find some error common to all the examples and to show that this error would still be committed even if those other fallacies that the examples exemplify were not. Aristotle (...) says that there is only one solution “against the argument” as opposed to “against the man”, and it is this solution the paper attempts to find. It is a characteristic mark of my analysis that some arguments that we might normally be inclined to say are fallacious turn out to be valid and that some arguments that we would normally be inclined to say are valid turn out to be fallacious. This is (in part) because what we call validity in modern logic is not the same as the apodicticity that Aristotelian syllogisms require in order to be used in science. The fallacies of accident, uniquely among the fallacies, are failures of apodicticity rather than failures of, in particular, semantic entailment. This makes sense in a tensed and token-based logic such as Aristotle’s. I conclude that the closest analogue to the fallacy of accident that we can point to is a fallacy in modal logic, viz., the fallacy of necessity. (shrink)

Three fallacies in the rationality debate obscure the possibility for reconciling the opposed camps. I focus on how these fallacies arise in the view that subjects interpret their task differently from the experimenters (owing to the influence of conversational expectations). The themes are: first, critical assessment must start from subjects' understanding; second, a modal fallacy; and third, fallacies of distribution.

There are three primary aims of the book. The first, set out in the book's introduction, is to explain how two fairly recent developments in philosophy, externalism and modalism, provide the basis for a promising account of knowledge - an account that achieves anti-skeptical results and avoids Gettier-style counterexamples that are based on an agent having warranted beliefs that are merely luckily true. Epistemological externalism is the thesis that not all the factors that make a true belief a case of (...) knowledge need to be cognitively accessible or "internal" to the agent. Modalism, as the author construes it, is the use of possible worlds talk in clarifying what would or might be the case and what is necessarily so." "The second objective is to work through the different modalized epistemologies extant in the literature, assessing their strengths and weaknesses, with a view toward constructing a working theory. Finally, the author proposes the theory that knowledge is reliably formed, sensitive true belief, and defends the theory against objections."--Jacket. (shrink)

The so-called New Theory of Reference (Marcus, Kripke etc.) is inspired by the insight that in modal and intensional contexts quantifiers presuppose nondescriptive unanalyzable identity criteria which do not reduce to any descriptive conditions. From this valid insight the New Theorists fallaciously move to the idea that free singular terms can exhibit a built-in direct reference and that there is even a special class of singular terms (proper names) necessarily exhibiting direct reference. This fallacious move has been encouraged by (...) a mistaken belief in the substitutional interpretation of quantifiers, by the myth of thede re reference, and a mistaken assimilation of direct reference to ostensive (perspectival) identification. Thede dicto vs.de re contrast does not involve direct reference, being merely a matter of rule-ordering (scope).The New Theorists' thesis of the necessity of identities of directly referred-to individuals is a consequence of an unmotivated and arbitrary restriction they tacitly impose on the identification of individuals. (shrink)

We introduce an expected-value theory of linguistic modality that makes reference to expected utility and a likelihood-based confirmation measure for deontics and epistemics, respectively. The account is a probabilistic semantics for deontics and epistemics, yet it proposes that deontics and epistemics share a common core modal semantics, as in traditional possible-worlds analysis of modality. We argue that this account is not only theoretically advantageous, but also has far-reaching empirical consequences. In particular, we predict modal versions of reasoning (...) class='Hi'>fallacies from the heuristics and biases literature. Additionally, we derive the modal semantics in an entirely transparent manner, as it is based on the compositional semantics of Korean modal expressions that are morphosyntactically decomposed into a conditional and an evaluative predicate. (shrink)

According to Etchemendy, in attempting to offer an analysis of the modal features of the intuitive concept of logical consequence, Tarski has committed a modal fallacy. In this paper, I consider the thesis according to it is posible to analyze the modals properties of concept of logical consequence through of a generalization on set-theoretical interpretations. As is known, some philosophers have tried to argue for the transit from the general to the modal by showing that there are (...) enough settheoretic interpretations so as to be able to represent the modal features of the intuitive concept of consequence. As is also known, those people have encountered a lot of difficulties. In the present paper, I will try to show that those problems are related not with the specific possibility of accounting for the modal features by means of a set-theoretic notion of model but with the possibility of coming up with a precise mathematical theory for the concept of interpretation, and, as such, they can be solved by way of appealing to the usual solutions to this problem. (shrink)

The question, "Which modal logic is the right one for logical necessity?," divides into two questions, one about model-theoretic validity, the other about proof-theoretic demonstrability. The arguments of Halldén and others that the right validity argument is S5, and the right demonstrability logic includes S4, are reviewed, and certain common objections are argued to be fallacious. A new argument, based on work of Supecki and Bryll, is presented for the claim that the right demonstrability logic must be contained in (...) S5, and a more speculative argument for the claim that it does not include S4.2 is also presented. (shrink)

This paper attacks the modal ontological argument, as advocated by Plantinga among others. Whereas other criticisms in the literature reject one of its premises, the present line is that the argument is invalid. This becomes apparent once we run the argument assuming fictionalism about possible worlds. Broadly speaking, the problem is that if one defines “x” as something that exists, it does not follow that there is anything satisfying the definition. Yet unlike non-modal ontological arguments, the modal (...) argument commits this “existential fallacy” not in relation to the definition of ‘God’. Rather, it occurs in relation to the modal facts quantified over within a Kripkean modal logic. In brief, we can describe the modal facts by whichever logic we prefer—yet it does not follow that there are genuine modal facts, as opposed to mere facts-according-to-the-fiction. A broader consequence of the discussion is that the existential fallacy is an issue for many projects in “armchair metaphysics.”. (shrink)

One of the most pressing objections against Divine simplicity is that it entails what is commonly termed a ‘modal collapse’, wherein all contingency is eliminated and every true proposition is rendered necessarily true. In this paper, I show that a common form of this argument is in fact famously invalid and examine three ways in which the opponent of Divine simplicity might try to repair the argument. I conclude that there is no clear way of repairing the argument that (...) does not beg the question against the doctrine of Divine simplicity. (shrink)

Social media is known to be one of the finest achievements of the 21st century. However, it is no surprise that there are two sides to every coin. While there are a lot of advantages of social media in our day-to-day life it is difficult to ignore its negative consequences. As the interactions between people have increased so have the standards and expectations of people and undoubtedly, so has the mental distress that people constantly face. Multiple researches conducted on the (...) negative impacts of social media indicate towards the downside of social media, especially it's negative footprint on people's identities, social life, mental health and emotional well-being. Although there are various modalities that have been used to identify and solve the problems that people experience with social media, there are other modalities of counseling that have the potential to be effective and helpful but have not been explored in this regard. One such modality is Logic-Based Therapy. Logic-Based Therapy and Consultation is a philosophy-based practice that aims to help identify the different emotional and behavioral ways in which people upset themselves by their own faulty thinking. LBT identifies a number of fallacies or incorrect reasonings that people use very frequently in their lives and also suggests ways in which individuals can learn to cope with these fallacies. A lot of the fallacies identified by LBT can be seen in practice through social media. This paper aims at providing an insight into the reality of social media and online presence while highlighting the most common fallacies that people commit in emotional and behavioral reasoning as identified by LBT. The paper will also explore how and why people often commit these fallacies and suggest some antidotes to combat these fallacies. (shrink)

Recently it has become almost the received wisdom in certain quarters that Kripke models are appropriate only for something like metaphysical modalities, and not for logical modalities. Here the line of thought leading to Kripke models, and reasons why they are no less appropriate for logical than for other modalities, are explained. It is also indicated where the fallacy in the argument leading to the contrary conclusion lies. The lessons learned are then applied to the question of the status of (...) the formula. (shrink)

In his presidential address to the APA, Alvin Plantinga argues that the only sensible way to be an anti-realist is to be a theist. Anti-realism (AR) in this context is the epistemic analysis of truth that says, "(AR) necessarily, a statement is true if and only if it would be believed by an ideally [or sufficiently] rational agent/community in ideal [or sufficiently good] epistemic circumstances." Plantinga demonstrates, with modest modal resources, that AR entails that necessarily, ideal epistemic circumstances obtain. (...) As it is a contingent matter whether ideal epistemic circumstances obtain, Plantinga concludes that an anti-realist should be a theist. In this paper, we show that counterfactual analyses of truth as epistemic are instances of a more general problem of philosophical analysis. More specifically, without a radical revision of the logic, counterfactual analyses of truth as epistemic cannot avoid perpetrating some version of the conditional fallacy. Even so, we argue, anti-realists are not committed to the necessary existence of ideal epistemic circumstances and therefore need not be theists. (shrink)

Paradoxes of nested modality, like Chisholm’s paradox, rely on S4 or something stronger as the propositional logic of metaphysical modality. Sarah-Jane Leslie’s objection to the resolution of Chisholm’s paradox by means of rejection of S4 modal logic is investigated. A modal notion of essence congenial to Leslie’s objection is clarified. An argument is presented in support of Leslie’s crucial but unsupported assertion that, on pain of inconsistency, an object’s essence is the same in every possible world. A fallacy (...) in the argument is exposed. Alternative interpretations of Leslie’s objection are provided and are found to involve equivocation between different notions of “essence.” A material artifact’s modal essence, as distinct from its quiddity essence, could have been different than it is. (shrink)

The purpose of this paper is to examine some passages of Tarski‘s paper ’On the concept of logical consequence’ and to show that some recent readings of those passages are wrong. John Etchemendy has claimed that in those passages Tarski gave an argument purporting to show that the notion of logical consequence defined by him (as opposed to some pretheoretic notion of logical consequence) possesses certain modal properties. Etchemendy further claims that the argument he attributes to Tarski is fallacious. (...) Some of Etchemendy’s critics have granted him that Tarski did give an argument purporting to show that the defined notion possesses certain modal properties ; but they have claimed that Tarski’s argument was not a fallacious one. I will show that both Etchemendy and his critics are wrong; in the relevant passages, Tarski did not offer (nor did he intend to offer) an argument that the defined notion of logical consequence possesses any modal properties. (shrink)

The reasoning abilities of large language models (LLMs) are the topic of a growing body of research in artificial intelligence and cognitive science. In this paper, we probe the extent to which a dozen LLMs are able to distinguish logically correct inferences from logically fallacious ones. We focus on inference patterns involving conditionals (e.g., 'If Ann has a queen, then Bob has a jack') and epistemic modals (e.g., 'Ann might have an ace', 'Bob must have a king'). These inference patterns (...) have been of special interest to logicians, philosophers, and linguists, since they plausibly play a central role in human reasoning. Assessing LLMs on these inference patterns is thus highly relevant to the question of how much the reasoning abilities of LLMs match those of humans. Among the LLMs we tested, all but GPT-4 often make basic mistakes with conditionals. Moreover, even GPT-4 displays logically inconsistent judgments across inference patterns involving epistemic modals. (shrink)

Most critics of Richard Swinburne’s modal argument for mind-body substance dualism have alleged that the argument is unsound, either because its premises are false or because it commits a modal fallacy. I show that the argument is epistemically circular, and thus provides no support for its conclusion even if it is sound.

The so-called New Theory of Reference (Marcus, Kripke etc.) is inspired by the insight that in modal and intensional contexts quantifiers presuppose nondescriptive unanalyzable identity criteria which do not reduce to any descriptive conditions. From this valid insight the New Theorists fallaciously move to the idea that free singular terms can exhibit a built-in direct reference and that there is even a special class of singular terms (proper names) necessarily exhibiting direct reference. This fallacious move has been encouraged by (...) a mistaken belief in the substitutional interpretation of quantifiers, by the myth of the de re reference, and a mistaken assimilation of "direct reference" to ostensive (perspectival) identification. The de dicto vs. de re contrast does not involve direct reference, being merely a matter of rule-ordering ("scope"). The New Theorists' thesis of the necessity of identities of directly refened-to individuals is a consequence of an unmotivated and arbitrary restriction they tacitly impose on the identification of individuals. (shrink)

The consequence argument for the incompatibility of free action and determinism has long been under attack, but two important objections have only recently emerged: Warfield’s modal fallacy objection and Campbell’s no past objection. In this paper, I explain the significance of these objections and defend the consequence argument against them. First, I present a novel formulation of the argument that withstands their force. Next, I argue for the one controversial claim on which this formulation relies: the trans-temporality thesis. This (...) thesis implies that an agent acts freely only if there is one time at which she is able to perform an action and a distinct time at which she actually performs it. I then point out that determinism, too, is a thesis about trans-temporal relations. I conclude that it is precisely because my formulation of the consequence argument emphasizes trans-temporality that it prevails against the modal fallacy and no past objections. (shrink)

Modal ontological arguments are often claimed to be immune to the flqqperfect islandfrqq objection of Gaunilo, because necessary existence does not apply to material, contingent things. But Gaunilo’s strategy can be reformulated: we can speak of non-contingent beings, like quasi-Gods or evil God. The paper is intended to show that we can construct ontological arguments for the existence of such beings, and that those arguments are equally plausible as theistic modal argument. This result does not show that this (...) argument is fallacious, but it shows that it is dialectically ineffective as an argument for theism. (shrink)

Motivated by semantic inferentialism and logical expressivism proposed by Robert Brandom, in this paper, I submit a nonmonotonic modal relevant sequent calculus equipped with special operators, □ and R. The base level of this calculus consists of two different types of atomic axioms: material and relevant. The material base contains, along with all the flat atomic sequents (e.g., Γ0, p |~0 p), some non-flat, defeasible atomic sequents (e.g., Γ0, p |~0 q); whereas the relevant base consists of the local (...) region of such a material base that is sensitive to relevance. The rules of the calculus uniquely and conservatively extend these two types of nonmonotonic bases into logically complex material/relevant consequence relations and incoherence properties, while preserving Containment in the material base and Reflexivity in the relevant base. The material extension is supra-intuitionistic, whereas the relevant extension is stronger than a logic slightly weaker than R. The relevant extension also avoids the fallacies of relevance. Although the extended material consequence relation is defeasible and insensitive to relevance, it has local regions of indefeasibility and relevance (the latter of which is marked by the relevant extension). The newly introduced operators, □ and R, codify these local regions within the same extended material consequence relation. (shrink)

In a recent article (Inquiry, Vol. 19 [1976]), J. W. Meiland addresses the issue of psychologism in logic, which holds that logic is a branch of psychology and that logical laws (such as the Principle of Non?Contradiction) are contingent upon the nature of the mind. Meiland examines Husserl's critique of psychologism, argues that Husserl is not convincing, and offers two new objections to the psychologistic thesis. In this paper I attempt to rebut those objections. In question are the acceptable criteria (...) for determining the possibility or impossibility of systems of logic significantly different from our own. I argue that a criteriological application of our accepted laws of logic to this question commits a circular fallacy. I then argue that, even if we accept logical consistency as a criterion for possibility, a plausible argument for the possibility of valid alternative logics can be constructed by using the functionalist analogy between minds and automata. Finally, I attempt to rebut the claim that in logic the only changes possible are conceptual changes that would not permit a proposition to be both true and false. (shrink)

This article systematically challenges Kripke's modal argument and Soames's defence of this argument by arguing that, just like descriptions, names can take narrow or wide scopes over modalities, and that there is a big difference between the wide scope reading and the narrow scope reading of a modal sentence with a name. Its final conclusions are that all of Kripke's and Soames's arguments are untenable due to some fallacies or mistakes; names are not “rigid designators”; if there (...) were rigid designators, description(s) could be rigidified to refer fixedly to objects; so names cannot be distinguished in this way from the corresponding descriptions. A descriptivist account of names is still correct; and there is no justification for Kripke's theory of rigid designation and its consequences. (shrink)

The aim of this paper is to discuss Kripkc?s reasons for declaring the existence of both necessary a posteriori as well as contingent a priori statements, thus breaking the traditional extensional coincidence of the two pairs of concepts:necessary?contingent and a priori?a posteriori. As I shall argue, there is no reason, from Kripke?s work at least, to reject the usual picture of the topic The appeal ot his arguments rests on the ambiguity with which his expressions are used and on the (...) introduction o\ new senses for old notions. This does not mean, however, that all Knpke?s and Putnam?s intuitions on singular terms and natural kind nouns are wrong. Once Kripke?s ideas are properly uudeistood, they are much moreharmless then they are presented to be and they do not pose a threat to traditional relations relations between modal and epistemological categories. (shrink)

In a 1990 paper, George Hughes axiomatized the logic determined by the class of all frames in which each point has a reflexive successor, and raised various questions along the way, one of which is answered incorrectly here by means of an interestingly fallacious argument.

The purpose of this study is to propose new similarity measures namely rough variational coefficient similarity measure under the rough neutrosophic environment. The weighted rough variational coefficient similarity measure has been also defined. The weighted rough variational coefficient similarity measures between the rough ideal alternative and each alternative are xxxxx calculated to find the best alternative. The ranking order of all the alternatives can be determined by using the numerical values of similarity measures. Finally, an illustrative example has been provided (...) to show the effectiveness and validity of the proposed approach. Comparisons of decision results of existing rough similarity measures have been provided. (shrink)

This paper is devoted to present Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method for multi-attribute group decision making under rough neutrosophic environment. The concept of rough neutrosophic set is a powerful mathematical tool to deal with uncertainty, indeterminacy and inconsistency. In this paper, a new approach for multi-attribute group decision making problems is proposed by extending the TOPSIS method under rough neutrosophic environment. Rough neutrosophic set is characterized by the upper and lower approximation operators and the (...) pair of neutrosophic sets that are characterized by truth-membership degree, indeterminacy membership degree, and falsity membership degree. In the decision situation, ratings of alternatives with respect to each attribute are characterized by rough neutrosophic sets that reflect the decision makers’ opinion. Rough neutrosophic weighted averaging operator has been used to aggregate the individual decision maker’s opinion into group opinion for rating the importance of attributes and alternatives. Finally, a numerical example has been provided to demonstrate the applicability and effectiveness of the proposed approach. (shrink)