What do logical positivists believe

Quine has criticized the distinction between analytic and synthetic statements, and the reduction of meaningful statements to immediate experience. Thomas Kuhn - has argued that it is just not possible to provide truth conditions for science, independent of its historical paradigm.

Donate with Crypto. A huge subject broken down into manageable chunks. Random Philosophy Quote :. Back to Top. History of Logical Positivism. While the list is long, it covers only a small fraction of those involved and leaves out many important thinkers. It is not possible in an essay of this scope to trace all the issues that the logical empiricists addressed or even to treat any one of them with completeness.

What is possible is to highlight some salient issues, clear away some misconceptions about them, and sketch a bit how those issues were developed over time. The first is a related set of concerns: empiricism, verificationism, and anti-metaphysics. Third is the related issues of the unity of science and reduction.

And finally, comes the issue of probability. Given what has already been said, the reader should be aware that none of the doctrines discussed below was shared by all members of the logical empiricist movement. Since antiquity the idea that natural science rests importantly on experience has been non-controversial. The only real questions about the sources of scientific knowledge are: Are there parts of science that do not rest on experience or rest also on something other than experience?

If so what account can we give of those parts? And to the extent that science does rest on experience how can we know that it does? There is another question about science related to these, though not strictly about the sources of science, and that is: Why, in making claims about the world, should we be scientific as opposed to say mystical?

The difficulty is that any scientific answer to this last question would reasonably be thought to beg the very question it purports to address. Long before the twentieth century the prevailing opinion was that Euclidean geometry, standard mathematics, and logic did not rest on experience in any obvious way. They were largely presupposed in our empirical work, and it was difficult to see what if anything might disconfirm them.

Geometry was a special case and might be handled in different ways that we shall not discuss here. That leaves logic and mathematics. If Frege and Russell were right, then mathematics could be thought of as expressing no more than logical truths and handled in whatever way logic was to be treated.

For Frege both mathematics and logic were analytic, but that, even if true, does not provide the needed answers. This seemed to open the way for a thoroughgoing empiricism in which the logical and mathematical fit in with the ordinary claims of physics and biology in a harmonious way.

The next subsection about analyticity discusses the question of whether the needed distinctions can be drawn. In developing his theory of types Russell said in effect that some expressions that seem to be sentences in fact say nothing at all. This is because, despite appearances, they are not grammatically well formed.

Wittgenstein found this suggestive. This does not mean, however, that all logical empiricists or even all members of the Vienna Circle accepted the strict verificationist view that in order to be meaningful a claim must be implied by a finite number of observation sentences.

Even though those observation sentences need not be true, this view had the drawback that so-called laws of nature would not be meaningful on this criterion.

Schlick was prepared to bite the bullet and hold that laws were not statements at all but principles of inference. Others were not prepared to go so far and sought more liberal formulations. Over the years a great many different formulations of verificationist principles ensued. Most of them came to a bad end rather quickly, and this is sometimes taken as a convincing argument that any form of verificationism is utterly misguided.

Perhaps, but we should be cautious. There are undoubtedly many different features joined in any one of the proposals, and even a sequence of failures may not show where to place the blame. The central idea behind verificationism is linking some sort of meaningfulness with in principle confirmation, at least for synthetic sentences. The actual formulations embodied not only such a link but various particular accounts of confirmation as well.

Now confirmation is a complex matter, and it is unlikely that we shall have the final satisfactory account any time soon. This should not persuade us, however, that there are no satisfactory accounts of confirmation any more than our current lack of the final physics should convince us that there are no physical facts of the matter.

So even a string of failures in formulating verificationist principles may mean no more than that the embedded accounts of confirmation are too simple but the link between meaningfulness and confirmation is nevertheless sound. Even if we set this caution aside, there may be parts of persistently employed strategy that lead to persistent failure. These parts and failures might be avoidable. To see how this may be so we will compare what is perhaps the most famous formulation of the verificationist principle, in Ayer , with a later one, in Carnap Ayer had visited the Vienna Circle from late on into , returning home for the summer term.

While in Vienna he attended meetings of the Circle and overlapped for five weeks with Quine. Neither Carnap nor Neurath were there at the time, so the left wing of the Circle was not fully represented.

Even immediately it was widely discussed, and after the war sales were spectacular. For many in England this book was the epitome of logical positivism and remains so. Ayer was careful to restrict his criterion of meaningfulness to synthetic sentences and to demand only in principle confirmation.

And the formulation seems very natural: Confirmation is a feature that applies to sentences or groups of them and not to sub-sentential parts, and for an empiricist the content that a synthetic sentence has would be empirical content. So it would seem that to have empirical content a sentence, A , should either directly imply some observational sentence or add to the observational content of some other sentence, B.

That is, the conjunction of A and B should imply some observational sentence not implied by B alone. This formulation may be natural, but it is also fatally flawed. The latter would not in general imply O , but the conjunction would. Other more elaborate formulations followed along the same lines, and other more elaborate counterexamples appeared just as fast. Hempel reviewed the situation twice within about a year Hempel and First he concluded that it was a lively and promising line of research and later concluded that it was not promising at all.

In retrospect it may be that the problems arise because we were led by the fact that confirmation is a feature that applies to whole sentences into thinking that the level at which to apply the criterion was the level of whole sentences.

Now a sentence with meaningless parts might well pass some test especially if the test involves its being combined with other sentences that can have meaningless parts. Observational terms are assumed to have empirical content. Logical terms are assumed to have none. And all defined terms are assumed to be replaced by their definitions. If for some basic, non-logical term there is a sentence that contains that term as its only non-logical element and if that sentence implies some observation sentence, then that sentence has empirical content and so does its only non-logical term.

If we have established that each term from some set, K , is empirically significant we might test still further terms by seeing whether those further terms can add to what is sayable with terms from K. It also allows an account of why those predecessors ran into trouble, viz. They became fairly well known, but they were not published until This does not show that there are no counterexamples or that there are no other features of the definition to which one might object.

But it does show that the situation is not as dire as Hempel supposed in We need to address another issue in considering verificationism, the persistent criticism that it is self-undercutting.

The argument for this claim goes like this: The principle claims that every meaningful sentence is either analytic or verifiable. Well, the principle itself is surely not analytic; we understand the meanings of the words in it perfectly well because we understand our own language. And we still do not think it true, so it cannot be true in virtue of meaning. This sounds more compelling than it is.

If so, then the sentence expressing the principle would indeed be analytic. So the self-undercutting charge strictly fails. But so construed and with nothing else said about it the principle would not have the same punch as before. Why should a metaphysician care whether his or her utterances lack some technical feature? Carnap is careful to distinguish the language for which the verifiability principle is given from the meta-language in which we talk about that language.

This meta-language would be the language in which the principle would be expressed. Carnap fully understands that if the general verificationist strategy is followed, there will also be a verificationist principle expressed in the meta-meta-language governing the meta-language.

By Carnap had introduced an important new element into his philosophy called the Principle of Tolerance. Tolerance is a radical idea.

Perhaps more precisely each of the various versions of empiricism including some sort of verificationism is best understood as a proposal for structuring the language of science. Before tolerance, both empiricism and verificationism are announced as if they are simply correct. Correspondingly, what Carnap called metaphysics is then treated as though it is, as a matter of brute fact, unintelligible. But what is announced thus dogmatically can be rejected equally dogmatically.

Once tolerance is in place, alternative philosophic positions, including metaphysical ones, are construed as alternative proposals for structuring the language of science. None of them is the uniquely correct one, and no theoretical argument or evidence can show that it is.

Nor can theoretical arguments or evidence show that it is false. Neither proposals nor languages are the sort of thing to be true or false. Instead, proposals call for practical decisions and practical arguments rather than for theoretical reasons or evidence.

Carnap believes that there are indeed very good practical reasons for adopting the proposal of verificationism, for choosing a language of science in which all substantive synthetic claims can, at least in principle, be brought before the court of public experience. That, he thinks, is the sad history of attempts to get beyond science, and it is just too painful. If the proposals constituting some version of verificationism are adopted, then in the language thus constituted it will be analytically true that there are no synthetic sentences that are both unverifiable and meaningful.

The notion of meaning here is not some new technical invention. No grammatically well-formed sentence of this new language violates the verifiability principle. And the principle itself is completely safe. Thought of in this way the verifiability principle does not describe natural language, it is not intended to.

It is intended to reform language to make it a more useful tool for the purposes of science. Carnap is under no illusion that natural languages are free from metaphysics. Nor is he under the illusion that defenders of the sort of metaphysics he targets will readily step up to the challenge of presenting precise rules of grammar and inference.

Before tolerance, verificationism is stated in such a way that violations would count only as unintelligible gibberish. With tolerance in place, Carnap is prepared to imagine non-empiricist languages, though of course he thinks they are very unwise. So instead of saying that sentences in non-empiricist languages are meaningless, he says that they are empirically meaningless. And that has a very different flavor.

There is no weakening of his defense of empiricism, but it is put on a somewhat different footing. Indeed it is hard to indicate any conditions under which any parts of them would be disconfirmed.

Leibniz had called them truths of reason. Hume said that they represented relations of ideas. Kant had held that the truths in these areas were a priori. Mathematics and geometry were not analytic for Kant, but logic was. Kant had two criteria of analyticity, apparently thinking them equivalent. First, in subject-predicate sentences, an analytic sentence is one in which the concept of the predicate is contained in that of the subject. Second, an analytic sentence is one whose denial is self-contradictory.

This seems to include not only the sentences whose surface logical form would be of the required sort but also those that can be got from such logical truths by making substitutions that were conceptually equivalent.

The more modern rough analog of this is to say that the analytic sentences are those that are true in virtue of logic and definition. Frege certainly developed logic beyond that which was available to Kant, but he did not think of himself as changing the analytic status of it. Logic is after all the only avenue we have for giving meaning to the notion of logical contradiction. Of course Frege also attempted to reduce mathematics to logic including both first and second order logic , and insofar as that reduction was successful it would have implied that mathematics was analytic as well.

Frege said little of geometry, but for him it was synthetic a priori. Carnap had not only studied with Frege, but like many of the logical empiricists he had started out as a neo-Kantian as well.

Geometry could be handled in several different ways that we will not discuss here. But from fairly early on there was widespread agreement among the logical empiricists that there was no synthetic a priori, and that logic and mathematics and perhaps much else that seemed impervious to empirical disconfirmation should be thought of as analytic. The point of drawing the analytic-synthetic distinction, then, is not to divide the body of scientific truths or to divide philosophy from science, but to show how to integrate them into a natural scientific whole.

Along the way the distinction clarifies which inferences are to be taken as legitimate and which are not. If, as Carnap and Neurath were, you are impressed by Duhemian arguments to the effect that generally claims must be combined in order to test them, the analytic-synthetic distinction allows you to clarify which combinations of claims are testable.

If analytic, a sentence is true in virtue of the conventions of language. In saying that, however, we must pause to confront two widespread confusions. First, Quine alleges , f that the notion of analyticity was developed and purports to explain for both Kant and Carnap how certainty is possible. In fact certainty has little or nothing to do with analyticity for the leading logical empiricists. In saying that such claims are based on convention they were explicitly calling attention to the revisability of conventions and the sentences that owed their meanings to those conventions.

No proposition can be made true by our conventions or decisions. But it is also completely irrelevant. Analyticity applies to sentences rather than propositions. Our conventions and decisions can and do affect what expressions mean and thus what sentences mean.

Once the meaning is specified, it may well be that any sentence that has this meaning would be true even if, for example, the point masses of the universe were arranged quite otherwise than they in fact are. These are the analytic sentences. No claim is being made that meaning causes anything or that convention makes anything true.

It is just that in these cases the truth value of the sentence may well be functionally dependent on meaning alone. If it is, then in this special sense, truth value depends on meaning, and that depends on convention.

Other sentences whose meanings are specified might well be true or false depending on how things in the external world, so to speak, are arranged.

In this other category of sentence the truth value is not functionally dependent on meaning alone. They are the synthetic sentences. Now this puts matters extremely informally. But at least the nature of the confusions over certainty and convention should be clear. The method used was to distinguish between a derivation relation the relation that holds between some premises and what can be got from them in a finite number of steps and a consequence relation.

The latter is an essentially semantic relation that holds between some premises and some other claim such that on all valuations under which the premises are all true, so is that other claim. In any case, Carnap is able to show that for any sentence of pure mathematics either it or its negation is a consequence of the null set of premises. As noted above, another innovation of Logical Syntax is the Principle of Tolerance.

In the late s Carnap began exploring a and how a notion of analyticity might be developed for novel theoretical terms where the theories in which those terms are embedded are presented by means of a system of postulates. It is not clear that the account he developed was intended to supersede his earlier account. Also let R TC be the Ramsey sentence for TC , that is, the result of replacing each of the non-observational terms in TC with predicate variables and closing that open sentence with corresponding existential quantifiers.

It may be suggested that this is a proposition which has already been proved by Kant. But although Kant also condemned transcendent metaphysics, he did so on different grounds. For he said that the human understanding was so constituted that it lost itself in contradictions when it ventured out beyond the limits of possible experience and attempted to deal with things in themselves.

And thus he made the impossibility of a transcendent metaphysic not, as we do, a matter of logic, but a matter of fact. He asserted, not that our minds could not conceivably have had the power of penetrating beyond the phenomenal world, but merely that they were in fact devoid of it. Our charge against the metaphysician is not that he attempts to employ the understanding in a field where it cannot profitably venture, but that he produces sentences which fail to conform to the conditions under which alone a sentence can be literally significant.

Nor are we ourselves obliged to talk nonsense in order to show that all sentences of a certain type are necessarily devoid of literal significance.

We need only formulate the criterion which enables us to test whether a sentence expresses a genuine proposition about a matter of fact, and then point out that the sentences under consideration fail to satisfy it. And this we shall now proceed to do. We shall first of all formulate the criterion in somewhat vague terms, and then give the explanations which are necessary to render it precise. Practical Verifiability vs. Verifiability in Principle. In the first place, it is necessary to draw a distinction between practical verifiability and verifiability in principle.

Plainly we all understand, in many cases believe, propositions which we have not in fact taken steps to verify. Many of these are propositions which we could verify if we took enough trouble. But there remain a number of significant propositions, concerning matters of fact, which we could not verify even if we chose; simply because we lack the practical means of placing ourselves in the situation where the relevant observations could be made.

A simple and familiar example of such a proposition is the proposition that there are mountains on the farther side of the moon.

No rocket has yet been invented which would enable me to go and look at the farther side of the moon, so that I am unable to decide the matter by actual observation. But I do know what observations would decide it for me, if, as is theoretically conceivable, I were once in a position to make them. And therefore I say that the proposition is verifiable in principle, if not in practice, and is accordingly significant. On the other hand, such a metaphysical pseudo-proposition as 'the Absolute enters into, but is itself incapable of, evolution and progress', is not even in principle verifiable.

For one cannot conceive of an observation which would enable one to determine whether the Absolute did, or did not, enter into evolution and progress. Of course it is possible that the author of such a remark is using English words in a way in which they are not commonly used by English-speaking people, and that he does, in fact, intend to assert something which could be empirically verified.

But until he makes us understand how the proposition that he wishes to express would be verified, he fails to communicate anything to us. And if he admits, as I think the author of the remark in question would have admitted, that his words were not intended to express either a tautology or a proposition which was capable, at least in principle, of being verified, then it follows that he has made an utterance which has no literal significance even for himself.

Strong Verification Conclusive vs. Weak Verification Probable. A further distinction which we must make is the distinction between the 'strong' and the 'weak' sense of the term 'verifiable'. A proposition is said to be verifiable, in the strong sense of the term, if and only if, its truth could be conclusively established in experience. But it is verifiable, in the weak sense, if it is possible for experience to render it probable.

In which sense are we using the term when we say that a putative proposition is genuine only if it is verifiable? It seems to me that if we adopt conclusive verifiability as our criterion of significance, as some positivists have proposed, our argument will prove too much.

Consider, for example, the case of general propositions of law -- such propositions, namely, as 'arsenic is poisonous'; 'all men are mortal'; 'a body tends to expand when it is heated'. It is of the very nature of these propositions that their truth cannot be established with certainty by any finite series of observations. But if it is recognized that such general propositions of law are designed to cover an infinite number of cases, then it must be admitted that they cannot, even in principle, be verified conclusively.

And then, if we adopt conclusive verifiability as our criterion of significance, we are logically obliged to treat these general propositions of law in the same fashion as we treat the statements of the metaphysician.

In face of this difficulty, some positivists have adopted the heroic course of saying that these general propositions are indeed pieces of nonsense, albeit an essentially important type of nonsense. But here the introduction of the term 'important' is simply an attempt to hedge. It serves only to mark the authors' recognition that their view is somewhat too paradoxical, without in any way removing the paradox.

Accordingly, we fall back on the weaker sense of verification. We say that the question that must be asked about any putative statement of fact is not, Would any observations make its truth or falsehood logically certain?

And it is only if a negative answer is given to this second question that we conclude that the statement under consideration is nonsensical. To make our position clearer, we may formulate it in another way. Let us call a proposition which records an actual or possible observation an experiential proposition.

Then we may say that it is the mark of a genuine factual proposition, not that it should be equivalent to an experiential proposition, or any finite number of experiential propositions, but simply that some experiential propositions can be deduced from it in conjunction with certain other premises without being deducible from those other premises alone.

This criterion seems liberal enough. In contrast to the principle of conclusive verifiability, it clearly does not deny significance to general propositions or to propositions about the past.

We begin by admitting that the fundamental ethical concepts are unanalysable, inasmuch as there is no criterion by which one can test the validity of the judgements in which they occur. So far we are in agreement with the absolutists [who hold that statements of value are not controlled by observation, but by a mysterious intellectual intuition]. But, unlike the absolutists, we are able to give an explanation of this fact about ethical concepts. We say that the reason why they are unanalysable is that they are mere pseudo-concepts.

The presence of an ethical symbol in a proposition adds nothing to its factual content. I am simply evincing my moral disapproval of it. The tone, or the exclamation marks, adds nothing to the literal meaning of the sentence.

It merely serves to show that the expression of it is attended by certain feelings in the speaker. It is clear that there is nothing said here which can be true or false. Another man may disagree with me about the wrongness of stealing, in the sense that he may not have the same feelings about stealing as I have, and he may quarrel with me on account of my moral sentiments. But he cannot, strictly speaking, contradict me.

For in saying that a certain type of action is right or wrong, I am not making any factual statement, not even a statement about my own state of mind. I am merely expressing certain moral sentiments. And the man who is ostensibly contradicting me is merely expressing his moral sentiments. So that there is plainly no sense in asking which of us is in the right. For neither of us is asserting a genuine proposition. Verifiability means possibility of verification. For our purpose it suffices to distinguish between two of the many ways in which the word 'possibility' is used.

We shall call them 'empirical possibility' and 'logical possibility'. I propose to call 'empirically possible' anything that does not contradict the laws of nature. This is, I think, the largest sense in which we may speak of empirical possibility; we do not restrict the term to happenings which are not only in accordance with the laws of nature but also with the actual state of the universe where 'actual' might refer to the present moment of our own lives, or to the condition of human beings on this planet, and so forth.

If we chose the latter definition. So 'empirical possibility' is to mean 'compatibility with natural laws'. Is the possibility of verification which we insist upon of this empirical sort? In that case there would be different degrees of verifiability, the question of meaning would be a matter of more or less, not a matter of yes or no. In many disputes concerning our issue it is the empirical possibility of verification which is discussed.

Many of those who refuse to accept our criterion of meaning seem to imagine that the procedure of its application in a special case is somewhat like this: A proposition is presented to us ready made, and in order to discover its meaning we have to try various methods of verifying or falsifying it, and if one of these methods works we have found the meaning of the proposition; but if not, we say it has no meaning.

If we really had to proceed in this way, it is clear that the determination of meaning would be entirely a matter of experience, and that in many cases no sharp and ultimate decision could be obtained. How could we ever know that we had tried long enough, if none of our methods were successful? Might not future efforts disclose a meaning which we were unable to find before? This whole conception is, of course, entirely erroneous.

It speaks of meaning as if it were a kind of entity inherent in a sentence and hidden in it like a nut in its shell, so that the philosopher would have to crack the shell or sentence in order to reveal the nut or meaning. Three of the most traditional explanations of crime are spiritual explanations, the classical school of criminology, and the positivist school of criminology.

Although developed in past centuries, all of these systems of thought influence our current system and ideas of justice. Researchers suggest that Classical School has changed the scope and range of punishment. Before, criminal justice systems implemented punishment in the form of pain.

People were whipped, tortured, hanged, beheaded, had limbs removed, as well as other forms of physical punishment. The positivist perspective in criminology looks to internal or external influences on individuals as the primary cause of criminal behaviour. Most attempts to explain crime over the last century have examined social factors as causes. The three subcultures are: criminal, conflict, and retreatist.

The positivist school of criminology uses scientific techniques to study crime and criminals and focuses on what factors compel offenders to commit crimes. The positivist school comprises many types of theories of crime, including biological, psychological, sociological, and critical sociological.

Ultimately, positivist criminology sought to identify other causes of criminal behavior beyond choice. The basic premises of positivism are measurement, objectivity, and causality. Early positivist theories speculated that there were criminals and non-criminals. Thus, we have to identify what causes criminals.