The modern discussion on the concept of truthlikeness was started in 1960. In his influential Word and Object, W. V. O. Quine argued that Charles Peirce's definition of truth as the limit of inquiry is faulty for the reason that the notion 'nearer than' is only "defined for numbers and not for theories". In his contribution to the 1960 International Congress for Logic, Methodology, and Philosophy of Science at Stan­ ford, Karl Popper defended the opposite view by defining a (...) compara­tive notion of verisimilitude for theories. The concept of verisimilitude was originally introduced by the Ancient sceptics to moderate their radical thesis of the inaccessibility of truth. But soon verisimilitudo, indicating likeness to the truth, was confused with probabilitas, which expresses an opiniotative attitude weaker than full certainty. The idea of truthlikeness fell in disrepute also as a result of the careless, often confused and metaphysically loaded way in which many philosophers used - and still use - such concepts as 'degree of truth', 'approximate truth', 'partial truth', and 'approach to the truth'. Popper's great achievement was his insight that the criticism against truthlikeness - by those who urge that it is meaningless to speak about 'closeness to truth' - is more based on prejudice than argument. (shrink)

Theories of truthlikeness (or verisimilitude) are currently being classified according to two independent distinctions: that between ‘content’ and ‘likeness’ accounts, and that between ‘conjunctive’ and ‘disjunctive’ ones. In this article, I present and discuss a new definition of truthlikeness, which employs Carnap’s notion of the content elements entailed by a theory or proposition, and is then labelled ‘Carnapian’. After studying in detail the properties and shortcomings of this definition, I argue that it occupies a unique position in the (...) landscape of different approaches to truthlikeness. More precisely, I show that it provides the only explication of truthlikeness which is both ‘conjunctive’ and ‘content-based’ in a suitably defined sense. (shrink)

Truthlikeness is a property of a theory or a proposition that represents its closeness to the truth. According to Niiniluoto, truthlikeness for quantitative deterministic laws can be defined by the Minkowski metric. I present some counterexamples to the definition and argue that it fails because it considers truthlikeness for quantitative deterministic laws to be just a function of accuracy, but an accurate law can be wrong about the actual ‘structure’ or ‘behaviour’ of the system it intends to (...) describe. I develop a modification of Niiniluoto’s proposal that defines truthlikeness for quantitative deterministic laws according to two parameters: accuracy and nomicity. The presented proposal solves the counterexamples and defines a new way of understanding scientific progress. (shrink)

How does scientifically informed metaphysics make progress? One idea is that metaphysics based on science makes progress on the back of science. If science makes progress, then so too does the metaphysics based on that science. Some argue that there is a problem with this line of reasoning. Kerry McKenzie claims that naturalistic metaphysics cannot make progress, even in principle, because metaphysical theories cannot approximate the truth as science can. In this paper, I offer a response to the worry McKenzie (...) raises. I claim that metaphysics is capable of making progress given an alternative account of scientific progress to hers, the truthlikeness account of progress. I argue that metaphysical theories, in principle, can increase in truthlikeness. According to the truthlikeness account of progress, if theories in a discipline increase in truthlikeness, then the discipline makes progress. Finally, I address two responses to an additional concern that those sharing McKenzie's perspective might have. In doing so, I sketch the groundwork for an alternative account of progress, one that leverages the tool-building approach to metaphysics that others have defended. (shrink)

In this paper, we offer a novel normative analysis of the inclusion fallacy. This refers to the robust tendency of experimental participants to reason about categories in a way that violates the laws of probability. In contrast to the received view, we argue that participants’ preferences in this kind of task might be rationally defended. To this purpose, we employ the philosophical notion of truthlikeness as a normative benchmark for category-based induction. Our analysis complements the main empirical findings and (...) theoretical predictions of the psychological literature and it explains the difficulties that probabilistic models have in treating cases like the inclusion fallacy. (shrink)

In a 2017 AJP paper, Cevolani and Schurz propose a novel solution to the Preface Paradox that appeals to the notion of expected truthlikeness. This discussion note extends and analyses their approach by applying it to the related Lottery Paradox.

The notion of truthlikeness or verisimilitude has been a topic of intensive discussion ever since the definition proposed by Karl Popper was refuted in 1974. This paper gives an analysis of old and new debates about this notion. There is a fairly large agreement about the truthlikeness ordering of conjunctive theories, but the main rival approaches differ especially about false disjunctive theories. Continuing the debate between Niiniluoto’s min-sum measure and Schurz’s relevant consequence measure, the paper also gives a (...) critical assessment of Oddie’s new defense of the average measure and Kuipers’ refined definition of truth approximation. (shrink)

The so-called Preface Paradox seems to show that one can rationally believe two logically incompatible propositions. We address this puzzle, relying on the notions of truthlikeness and approximate truth as studied within the post-Popperian research programme on verisimilitude. In particular, we show that adequately combining probability, approximate truth, and truthlikeness leads to an explanation of how rational belief is possible in the face of the Preface Paradox. We argue that our account is superior to other solutions of the (...) paradox, including a recent one advanced by Hannes Leitgeb (Analysis 74.1). (shrink)

Truthlikeness is a property of a theory or a proposition that represents its closeness to the truth. We start by summarizing Niiniluoto’s proposal of truthlikeness for deterministic laws, which defines truthlikeness as a function of accuracy, and García-Lapeña’s expanded version, which defines truthlikeness for DL as a function of two factors, accuracy and nomicity. Then, we move to develop an appropriate definition of truthlikeness for probabilistic laws based on Niiniluoto’s suggestion to use the Kullback–Leibler divergence (...) to define the distance between a probability law X\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$X$$\end{document} and the true probability law T\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$T$$\end{document}. We argue that the Kullback–Leibler divergence seems to be the best of the available probability distances to measure accuracy between PL. However, as in the case of DL, we argue that accuracy represents a necessary but not sufficient condition, as two PL may be equally accurate and still one may imply more true or truthlike consequences, behaviours or true facts about the system than the other. The final proposal defines truthlikeness for PL as a function of two factors, p-accuracy and p-nomicity, in intimate connexion with García-Lapeña’s proposal for DL. (shrink)

Truthlikeness in historiography would allow us to be optimistic fallible realists about historiography – to hold that historical knowledge is about the past, true albeit fallible, and can increase over time. In this paper, three desiderata for a concept of truthlikeness in historiography will be outlined. One of the main challenges for truthlikeness is historiographic skepticism which holds that historiography is indistinguishable from fiction and cannot therefore furnish us with true knowledge about the past. Such skepticism rests (...) on the postmodern challenge, which will be criticized on the grounds that it rests on an implausible theory of meaning. It will be shown that Peirce’s semeiotic and pragmatist theory of truth, interpreted dialogically or game-theoretically, provides a suitable framework within which to pursue the project of defining a concept of truthlikeness for historiography. Finally, directions for possible future research into truthlikeness in historiography, including ways of defining a measure of truthlikeness, will be considered. (shrink)

A qualitative theory of truthlikeness, based on a family of quantitative measures, is developed for hypotheses that are concerned with the values of a finite number of real-valued quantities. Representing hypotheses by subsets of $R^{n}$ , I first show that a straightforward application of the basic ideas of the similarity approach to truthlikeness does not work out for hypotheses with zero n-dimensional Lebesgue measure. However, it is easy to give a counterpart for the average measure preferred by Pavel (...) Tichý and Graham Oddie in terms of Hausdorff measures. The task of finding analogies of the min-sum-measure preferred by Ilkka Niiniluoto is more interesting. I present and discuss analogies of two different types for this measure. (shrink)

Examples of hypotheses about the number of planets are frequently used to introduce the topic of (actual) truthlikeness but never analyzed in detail. In this paper we first deal with the truthlikeness of singular quantity hypotheses, with reference to several ‘the number of planets’ examples, such as ‘The number of planets is 10 _versus_ 10 billion (instead of 8).’ For the relevant ratio scale of quantities we will propose two, strongly related, normalized metrics, the proportional metric and the (...) (simplest and hence favorite) fractional metric, to express e.g. the distance from a hypothetical number to the true number of planets, i.e. the distance between quantities. We argue that they are, in view of the examples and plausible conditions of adequacy, much more appropriate, than the standardly suggested, normalized absolute difference, metric. Next we deal with disjunctive hypotheses, such as ‘The number of planets is between 7 and 10 inclusive is much more truthlike than between 1 and 10 billion inclusive.’ We compare three (clusters of) general ways of dealing with such hypotheses, one from Ilkka Niiniluoto, one from Pavel Tichý and Graham Oddie, and a trio of ways from Theo Kuipers. Using primarily the fractional metric, we conclude that all five measures can be used for expressing the distance of disjunctive hypotheses from the actual truth, that all of them have their strong and weak points, but that (the combined) one of the trio is, in view of principle and practical considerations, the most plausible measure. (shrink)

The most elaborate recent accounts of truthlikeness (verisimilitude) apply this notion primarily to generalizations in first-order languages with qualitative predicates. This paper outlines a new approach to the definition of truthlikeness for quantitative statements, including singular statements (point estimation), interval statements (interval estimation), and quantitative laws. In the case of laws, the basic issue is reduced to the topological problem of measuring the distance between two real-valued functions. The solution of this problem makes it possible to define also (...) the notion of approximate truth for quantitative laws. (shrink)

In a series of carefully argued and stimulating papers on realism, Usakli Maki has pointed out that economic theories typically are unrealistic in two senses: by violating "the-whole-truth" and "nothing-but-the-truth" (Maki 1989, 1992b, 1994b). He suggests that realism in economics can still be rescued by regarding theories as partially true descriptions of essences and as lawlike statements about tendencies. In this chapter, I defend realism by an alternative strategy: idealizational (or "isolational") statements are counterfactual conditional (Niiniluoto 1986), and the concepts (...) of truth and truthlikeness can be applied to them (Niiniluoto 1987). Further, false but sufficiently truthlike theories may be taken to refer to real entities in the world (Niiniluoto 1997, 1999). (shrink)

The paper starts with the distinction between conjunction-of-parts accounts and disjunction-of-possibilities accounts to truthlikeness. In Sect. 3, three distinctions between kinds of truthlikeness measures are introduced: comparative versus numeric t-measures, t-measures for qualitative versus quantitative theories, and t-measures for deterministic versus probabilistic truth. These three kinds of truthlikeness are explicated and developed within a version of conjunctive part accounts based on content elements. The focus lies on measures of probabilistic truthlikeness, that are divided into t-measures for (...) statistical probabilities and single case probabilities. The logical notion of probabilistic truthlikeness can be treated as a subcase of deterministic truthlikeness for quantitative theories. In contrast, the epistemic notion of probabilistic truthlikeness creates genuinely new problems, especially for hypotheses about single case probabilities that are evaluated not by comparison to observed frequencies, but by comparison to the truth values of single event statements. By the method of meta-induction, competing theories about single case probabilities can be aggregated into a combined theory with optimal predictive success and epistemic truthlikeness. (shrink)

D. Miller's demonstrations of the language dependence of truthlikeness raise a profound problem for the claim that scientific progress is objective. In two recent papers (Barnes 1990, 1991) I argue that the objectivity of progress may be grounded on the claim that the aim of science is not merely truth but knowledge; progress thus construed is objective in an epistemic sense. In this paper I construct a new solution to Miller's problem grounded on the notion of "approximate causal explanation" (...) which allows for linguistically invariant progress outside an epistemic context. I suggest that the notion of "approximate causal explanation" provides the resources for a more robust theory of progress than that provided by the notion of "approximate truth.". (shrink)

There are two main approaches used to evaluate someone’s epistemic accuracy. On one hand, we have the approach that evaluates the truthlike-ness of some propositions and orders them by their closeness to truth. On the other hand, we can look at someone’s probability assignments and then calculate the accuracy using the Brier score. Recently, Oddie tried to show that these two methods are in tension, because a measure that obeys probabilism will fail to hold Proximity. I argue that the Unified (...) Approach can be saved and, moreover, has some important advantages over the isolated Truthlikeness. (shrink)

There is an ongoing debate about which rule we ought to use for scoring probability estimates. Much of this debate has been premised on scoring-rule monism, according to which there is exactly one best scoring rule. In previous work, I have argued against this position. The argument given there was based on purely a priori considerations, notably the intuition that scoring rules should be sensitive to truthlikeness relations if, and only if, such relations are present among whichever hypotheses are (...) at issue. The present paper offers a new, quasi-empirical argument against scoring-rule monism. This argument uses computational simulations to show that different scoring rules can have different economical consequences, depending on the context of use. (shrink)

In the 1970's a problem arose for the viability of Popper's truthlikeness project. The problem, in short, was that all plausible measures of the truthlikeness of scientific theories were language dependent. This dissertation is primarily concerned to provide a substitute notion that can do the work 'verisimilitude' was intended to do without suffering from linguistic relativity. It is argued that the notion of 'knowledge', or 'knowledgelikeness', can suffice in this regard. ;Chapter One seeks to convince the reader that (...) the notion of 'truthlikeness' is intrinsically non-objective; all attempts to salvage the objectivity of truthlikeness have failed. Chapters Two, Three, and Four argue that the various language dependence arguments can be overcome by adopting a knowledge-based approach. Chapter Five attempts to diagnose the underlying cause behind the failure of the verisimilitude project. (shrink)

In this paper, I propose and defend a new criterion for appropriate choice under conditions of moral uncertainty. According to this new criterion, it is appropriate to follow some moral theory T under conditions of moral uncertainty iff T maximises expected truthlikeness. This approach to moral uncertainty has several important advantages: (1) it does not require any intertheoretic choiceworthiness comparisons; (2) it respects agent-centred prerogatives and supererogation; (3) it does not suffer from any ‘individuation problems’; and (4) it has (...) a prima facie plausible motivating idea. (shrink)

This book is concerned with the problem of applying the theory of verisimilitude to cognitive problems of a quantitative nature. Attention is mostly focused on hypotheses concerned with (physical or other) systems whose state can be represented with an element of a multidimensional state space, but hypotheses concerned with quantitative laws are also considered. The book provides a systematic introduction to the main contemporary forms of the theory of verisimilitude, including both proposed definitions of quantitative degrees of verisimilitude and proposed (...) definitions of the relation `closer to the truth than'. It shows why the quantitative measures that have been proposed earlier produce unacceptable results in the multidimensional case and, using the tools of geometric measure theory, works out alternatives for them in detail. In addition, the standard structuralist theory of science and the way in which the problems of approximation are dealt with in it are presented and evaluated critically. (shrink)

Woosuk Park’s paper “Misrepresentation in Context” is a useful plea for a theory of representation with promising interaction between cognitive science, philosophy of science, and aesthetics. In this paper, I argue that such a unified account is provided by Charles S. Peirce’s semiotics. This theory puts Park’s criticism of Nelson Goodman and Jerry Fodor in context. Some of Park’s pertinent remarks on the problem of misrepresentation can be illuminated by the account of truthlikeness and idealization developed by philosophers of (...) science. (shrink)

In this paper, an attempt is made to solve various problems posed to current theories of verisimilitude: the problem of linguistic variance; the problem of which are the best scientific methods for getting the most verisimilar theories; and the question of the ontological commitment in scientific theories. As a result of my solution to these problems, and with the help of other considerations of epistemological character, I conclude that the notion of 'Tarskian truth' is dispensable in a rational interpretation of (...) the scientific enterprise. As a logical result, however, falsificationism will be vindicated. (shrink)

Harry Lloyd argues for a new solution to the problem of rationally choosing under moral uncertainty—what he calls *My Preferred Theory*. I show that my preferred theory is in fact the moral theory with the greatest expected truthlikeness.

This paper studies the interplay between two notions which are important for the project of defending scientific realism: abduction and truthlikeness. The main focus is the generalization of abduction to cases where the conclusion states that the best theory is truthlike or approximately true. After reconstructing the recent proposals of Theo Kuipers within the framework of monadic predicate logic, I apply my own notion of truthlikeness. It turns out that a theory with higher truthlikeness does not always (...) have greater empirical success than its less truthlike rivals. It is further shown that the notion of expected truthlikeness provides a fallible link from the approximate explanatory success of a theory to its truthlikeness. This treatment can be applied also in cases where even the best potential theory is an idealization that is known to be false. (shrink)

A holistic account of the meaning of theoretical terms leads scientific realism into serious troubles. Alternative methods of reference fixing are needed by a realist who wishes to show how reference invariance is possible in spite of meaning variance. This paper argues that the similarity theory of truthlikeness and approximate truth, developed by logicians since the mid 1970s, helps to make precise the idea of charitable theoretical reference. Comparisons to the recent proposals by Kitcher and Psillos are given. This (...) argument helps to undermine the scepticist meta-induction about theories, and thereby to reevaluate Laudan's alleged confutation of scientific realism. (shrink)

The notion of truthlikeness, coined by Karl Popper, has very much fallen into oblivion, but the paper defends it. It can be regarded in two different ways. Either as a notion that is meaningful only if some formal measure of degree of truthlikeness can be constructed; or as a merely non-formal comparative notion that nonetheless has important functions to fulfill. It is the latter notion that is defended; it is claimed that such a notion is needed for both (...) a reasonable backward-looking and a reasonable forward-looking view of science. On the one hand, it is needed in order to make sense of the history of science as containing a development; on the other, it is needed in order to understand present-day sciences as containing knowledge-seeking activities. The defense of truthlikeness requires also a defense of two other notions: quasi-comparisons and regulative ideas, which is supplied in this paper as well. (shrink)

Moderate realists hold that scientific theories are truthlike, rather than exactly true. Although scientific realism has been challenged by arguments such as the pessimistic induction, moderate realism hasn’t been challenged directly on the grounds that it makes scientific progress rely on inferences from theories that are only truthlike. This paper shows that moderate realism is incompatible with the claim that deductive arguments from scientific theories are reliable. Using truthlike claims as the premises of some patterns of deductive reasoning renders the (...) argument dramatically unreliable. The conclusion is not guaranteed to be true. Nor is the conclusion guaranteed to be at least as truthlike as the premises. Nor even is the conclusion shown to be likely to be true. This is because the consequences of truthlike theories are neither guaranteed to be true, nor even more likely to be truthlike than not. Truthlike theories cannot function like true theories in deductive arguments; instead they function as radically false theories would. In short, truthlike theories behave exactly like radically false theories for the purposes of their deductive consequences. And since scientists would not trust deductions from radically false theories, they should not trust deductions from truthlike theories either. Furthermore, this applies to a wide range of logics and patterns of deductive argument. The moderate realist must either reject bivalence, deny that theories are truth-apt, or accept that scientific theories are not used in deductive arguments. (shrink)

Verisimilitude theorists (and many scientific realists) assume that science attempts to provide hypotheses with an increasing degree of closeness to the full truth; on the other hand, radical sociologists of science assert that flesh and bone scientists struggle to attain much more mundane goals (such as income, power, fame, and so on). This paper argues that both points of view can be made compatible, for (1) rational individuals only would be interested in engaging in a strong competition (such as that (...) described by radical sociologists) if they knew in advance the rules under which their outcomes are to be assessed, and (2), if these rules have to be chosen "under a veil of ignorance" (i.e., before knowing what specific theory each scientist is going to devise), then rules favoring highly verisimilar theories can be prefered by researchers to other methodological rules. (shrink)

Verisimilitude theorists assume that science attempts to provide hypotheses with an increasing degree of closeness to the full truth; on the other hand, radical sociologists of science assert that flesh and bone scientists struggle to attain much more mundane goals. This paper argues that both points of view can be made compatible, for rational individuals only would be interested in engaging in a strong competition if they knew in advance the rules under which their outcomes are to be assessed, and, (...) if these rules have to be chosen "under a veil of ignorance", then rules favoring highly verisimilar theories can be prefered by researchers to other methodological rules. (shrink)

So far, the most prominent measure for actual truthlikeness, i.e. the likeness of a theory to the actual truth, is Ilkka Niiniluoto’s minsum definition, which is purely based on distances. A competing definition is the average distance measure proposed by Pavel Tichy and Graham Oddie. We will define three related, distance and size based, measures for actual truthlikeness and compare them with the two well-known options. However, we will start, Sect. 2, from a trio of such measures for (...) nomic truthlikeness. The nomic truth, or the true theory, here refers to what is nomically, e.g. physically, possible. In a nomic (and factual) context there are two basic kinds of theories, viz. either based on an exclusion claim or on an inclusion claim. Two-sided theories combine these claims, with the maximal claim as extreme special case. We will base truthlikeness measures for exclusion, inclusion, two-sided, and hence maximal, nomic theories on two similarity measures, one in terms of distances between conceptual possibilities and the other in terms of sizes of sets of such possibilities. In Sect. 3 we will treat actual truthlikeness as extreme special case of nomic truthlikeness, viz. assuming that there is just one nomic possibility, the actual one. Next we will compare the resulting measures mutually and with the above mentioned measures of Niiniluoto and Tichy & Oddie. Finally, in Sect. 4, we will sum up the results and explore five questions for further research. (shrink)

Lies come in different sizes. There are little white lies, slight stretches, exaggerations, fibs, and whoppers. Such terms can reflect different aspects of lies, but one of these is how far a lie is from what the liar really thinks. This paper proposes that this dimension of lie-size reflects a scalar aspect of sincerity. Drawing inspiration from the study of truthlikeness, the paper elucidates this aspect of sincerity, which I call “truthful-likeness”. Truthful-likeness reflects how sincere a reply to a (...) question is, based on how close the speaker takes the reply to be to their best available one. A related measure, expected subjective truth factor, reflects how sincere a constative act that is not a reply to a question is, based on how close to being true the speaker thinks it is. (shrink)