Tag Archives: correspondence theory of truth

The truth, the whole truth and … wait, how many truths are there?

The Conversation

Peter Ellerton, The University of Queensland

Calling something a “scientific truth” is a double-edged sword. On the one hand it carries a kind of epistemic (how we know) credibility, a quality assurance that a truth has been arrived at in an understandable and verifiable way.

On the other, it seems to suggest science provides one of many possible categories of truth, all of which must be equal or, at least, non-comparable. Simply put, if there’s a “scientific truth” there must be other truths out there. Right?

Let me answer this by reference to the fingernail-on-the-chalkboard phrase I’ve heard a little too often:

“But whose truth?”

If somebody uses this phrase in the context of scientific knowledge, it shows me they’ve conflated several incompatible uses of “truth” with little understanding of any of them.

As is almost always the case, clarity must come before anything else. So here is the way I see truth, shot from the hip.

Venture Vancouver

While philosophers talk about the coherence or correspondence theories of truth, the rest of us have to deal with another, more immediate, division: subjective, deductive (logical) and inductive (in this case, scientific) truth.

This has to do with how we use the word and is a very practical consideration. Just about every problem a scientist or science communicator comes across in the public understanding of “truth” is a function of mixing up these three things.

Subjective truth

Subjective truth is what is true about your experience of the world. How you feel when you see the colour red, what ice-cream tastes like to you, what it’s like being with your family, all these are your experiences and yours alone.

In 1974 the philosopher Thomas Nagel published a now-famous paper about what it might be like to be a bat. He points out that even the best chiropterologist in the world, knowledgeable about the mating, eating, breeding, feeding and physiology of bats, has no more idea of what it is like to be a bat than you or me.

Similarly, I have no idea what a banana tastes like to you, because I am not you and cannot ever be in your head to feel what you feel (there are arguments regarding common physiology and hence psychology that could suggest similarities in subjective experiences, but these are presently beyond verification).

What’s more, if you tell me your favourite colour is orange, there are absolutely no grounds on which I can argue against this – even if I felt inclined. Why would I want to argue, and what would I hope to gain? What you experience is true for you, end of story.

Deductive truth

Deductive truth, on the other hand, is that contained within and defined by deductive logic. Here’s an example:

Premise 1: All Gronks are green.
Premise 2: Fred is a Gronk.
Conclusion: Fred is green.

Even if we have no idea what a Gronk is, the conclusion of this argument is true if the premises are true. If you think this isn’t the case, you’re wrong. It’s not a matter of opinion or personal taste.


If you want to argue the case, you have to step out of the logical framework in which deductive logic operates, and this invalidates rational discussion. We might be better placed using the language of deduction and just call it “valid”, but “true” will do for now.

In my classes on deductive logic we talk about truth tables, truth trees, and use “true” and “false” in every second sentence and no one bats (cough) an eyelid, because we know what we mean when we use the word.

Using “true” in science, however, is problematic for much the same reason that using “prove” is problematic (and I have written about that on The Conversation before). This is a function of the nature of inductive reasoning.

Inductive truth

Induction works mostly through analogy and generalisation. Unlike deduction, it allows us to draw justified conclusions that go beyond the information contained in the premise. It is induction’s reliance on empirical observation that separates science from mathematics.

In observing one phenomenon occurring in conjunction with another – an electric current and an induced magnetic field, for instance – I generalise that this will always be so. I might even create a model, an analogy of the workings of the real world, to explain it – in this case that of particles and fields.

This then allows me to predict what future events might occur or to draw implications and create technologies, such as developing an electric motor.

And so I inductively scaffold my knowledge, using information I rely upon as a resource for further enquiry. At no stage do I arrive at deductive certainty, but I do enjoy greater degrees of confidence.

I might even speak about things being “true”, but, apart from simple observational statements about the world, I use the term as a manner of speech only to indicate my high level of confidence.

Now, there are some philosophical hairs to split here, but my point is not to define exactly what truth is, but rather to say there are differences in how the word can be used, and that ignoring or conflating these uses leads to a misunderstanding of what science is and how it works.

For instance, the lady that said to me it was true for her that ghosts exist was conflating a subjective truth with a truth about the external world.

I asked her if what she really meant was “it is true that I believe ghosts exist”. At first she was resistant, but when I asked her if it could be true for her that gravity is repulsive, she was obliging enough to accept my suggestion.


Such is the nature of many “it’s true for me” statements, in which the epistemic validity of a subjective experience is misleadingly extended to facts about the world.

Put simply, it smears the meaning of truth so much that the distinctions I have outlined above disappear, as if “truth” only means one thing.

This is generally done with the intent of presenting the unassailable validity of said subject experiences as a shield for dubious claims about the external world – claiming that homeopathy works “for me”, for instance. Attacking the truth claim is then, if you accept this deceit, equivalent to questioning the genuine subject experience.

Checkmate … unless you see how the rules have been changed.

It has been a long and painful struggle for science to rise from this cognitive quagmire, separating out subjective experience from inductive methodology. Any attempt to reunite them in the public understanding of science needs immediate attention.

Operating as it should, science doesn’t spend its time just making truth claims about the world, nor does it question the validity of subject experience – it simply says it’s not enough to make object claims that anyone else should believe.

Subjective truths and scientific truths are different creatures, and while they sometimes play nicely together, their offspring are not always fertile.

So next time you are talking about truth in a deductive or scientifically inductive way and someone says “but whose truths”, tell them a hard one: it’s not all about them.

The ConversationPeter Ellerton, Lecturer in Critical Thinking, The University of Queensland

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.


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Searle’s case for realism

by Tim Harding

Towards the end of his book ‘The Construction of Social Reality’, John Searle [1] makes a case for realism, which he defines as ‘the view that the world exists independently of our representations of it’ (Searle 1995: 153).  He first responds to what he sees as the main objections to this view (Searle 1995: 149-176); and then provides some arguments in favour of it (Searle 1995: 177-197).  Searle also discusses the correspondence theory of truth which he sees as related to realism (Searle 1995: 199-226).  In this essay, I shall present Searle’s arguments and responses in the reverse order to his, and then I shall discuss what I see as the strengths and weaknesses of his case.  My thesis is essentially that an external reality is consistent with both Searle’s construction of social reality and the correspondence theory of truth.

Searle commences his case in favour of realism by noting the methodological difficulty of an unavoidable element of circularity in the arguments.  Just as it is difficult to justify rationality in other than rational terms, it is difficult to justify the framework of reality from within the same framework.  He notes that:

“One can show that this or that claim corresponds to or fails to correspond to how things really are in the ‘external world’, but one cannot in that way show that the claim that there is an external world corresponds to how things are in the external world, because any question of corresponding or failing to correspond to the external world already presupposes the existence of an external world to which the claim corresponds or fails to correspond.” (Searle 1995: 178).

He then cites what he describes as the standard argument for realism, which is that convergence in science provides a kind of empirical proof of realism.  He says that the best explanation for this phenomenon is an independently existing reality that causes different scientists to converge on the same hypotheses, theories and experimental results.  However, Searle notes the methodological difficulty referred to above – that the recognition of convergence presupposes realism (Searle 1995: 179).  There is also another possible explanation of scientific instrumentalism, which I shall discuss later.

Searle next turns to G.E. Moore’s ‘proof’ of realism, in which Moore argued that the proposition that he has two hands entails the proposition that the external world exists (Moore 1962: 144-8).  Searle notes two problems with Moore’s proof.  The first is the assumption that external reality is a truth condition like any other; and the second is the related assumption that realism is a theory about external objects in space.  Searle responds that external reality is not an empirical thesis but a condition of intelligibility for having empirical theses.  He carefully states that ‘external realism is the thesis that there is a way that things are that is independent of all representations of how things are’ (Searle 1995: 181-182).

Following on from this observation, Searle then proposes what he calls a ‘transcendental’ argument against phenomenalist idealism.  This is argument assumes that a certain condition obtains and then tries to show the background presuppositions of that condition.  In this case, the condition is that we attempt to communicate with each other by making certain sorts of utterances and the presupposition behind these utterances is external realism.  Realism does not say how things are but only that there is a way that they are that is independent of our representations (Searle 1995: 155, 183-188).

Searle next makes a logical connection between external reality and the socially constructed reality that forms the earlier chapters of his book.  He argues that ‘a socially constructed reality presupposes a reality independent of social constructions, because there has to be something for the construction to be constructed out of’.  For example, to socially construct money, property and language, there have to be the physical raw materials of metal, paper, land and sounds.  In other words, the ontological subjectivity of the socially constructed reality requires an ontologically objective reality out of which it is constructed.  He says that it is a logical consequence of the main argument of his book being that you cannot have institutional facts without brute facts (Searle 1995: 190-191).

Another logical connection is with the correspondence theory of truth, which Searle makes a case for in the final chapter of his book (Searle 1995: 199-228).   This theory implies realism since it implies that there is a reality to which statements correspond if they true . (Searle 1995: 154).

I would now like to turn to the three main arguments that Searle identifies as the most powerful against external realism.  These are the argument from conceptual relativity, the verificationist argument and what he calls the Ding an sich argument (Searle 1995: 160).

Conceptual relativity is the thesis that systems of representation, such as vocabularies and conceptual schemes generally, are human creations and to that extent arbitrary and multiply possible (Searle 1995: 151).  Several philosophers have supposed that external realism is inconsistent with conceptual relativity, but Searle disagrees.  He says that former idea just says that there is something out there to be described; whereas the latter idea says that we need to select a set of concepts and vocabulary to describe it.  The second idea does not entail a negation of the first (Searle 1995: 161).

“The fact that alternative conceptual schemes allow for different descriptions of the same reality, and that there are no descriptions of reality outside all conceptual schemes, has no bearing whatsoever on the truth of realism” (Searle 1995: 165).

The verificationist argument against realism is essentially that there is no way of verifying a reality independent of human experience and knowledge.  Searle identifies two strands to this argument.  The first is that because all we can ever perceive are our own experiences, if there is a reality beyond our experiences, then it is unknowable.  By extension, the second strand is that if claims about the real world go beyond the content of our experiences, then we are postulating something for which we have no epistemic basis (Searle 1995: 169-170).

Searle believes that both strands of the verificationist argument are mistaken.  For example, if he sees his desk in front of him, he is having a perceptual experience, but he does not ‘conclude’ on the basis of ‘evidence’ that there is a desk there; rather, he simply sees the desk.  It does not follow that it the existence of the desk is unknowable (Searle 1995: 170-173).

The Ding an sich argument is essentially a combination of the argument from conceptual relativity and the verificationist argument.  It is that not only is an external reality beyond the grasp of knowledge, but also our language and thought.  The alleged problem with such a realism is not that it is false, but that it is ultimately unintelligible (Searle 1995: 173-174).  Searle explicitly states the argument in terms of the following premise and conclusions:

“Premise: Any cognitive state occurs as part of a set of cognitive states and within a cognitive system.

Conclusion 1: It is impossible to get outside of all cognitive states and systems to survey the relationships between them and the reality they are used to cognize.

Conclusion 2: No cognition is ever of a reality that exists independently of cognition.”

In this argument, conclusion 2 is supposed to logically follow from conclusion 1. Whilst Searle concedes that conclusion 1 follows from the premise, he does not concede that conclusion 2 logically follows from conclusion 1.  He says that ‘it simply does not follow that from the fact that all cognition is within a cognitive system that no cognition is ever directly of a reality that exists independently of all cognition’ (Searle 1995: 174-175).

Having outlined Searle’s arguments for realism and his responses to the main objections to it, I would now like to discuss what I see as the main weaknesses and then the strengths of Searle’s case.

First, Searle claims that external reality is the best explanation for convergence in scientific hypotheses, theories and results; but he fails to mention alternative explanations such as scientific instrumentalism.  According to instrumentalists, scientific theory is merely a tool used by scientists to predict observations, without revealing or even relying on the existence of external reality (Torretti, 1999: 242–43).

Second, Searle notes problems with Moore’s ‘proof’ of external realism without stating the main argument in favour of it, which has become known as the ‘the G. E. Moore shift’ as follows.  Consider a standard sort of skeptical argument:

Premise 1: If I cannot tell the difference between waking and dreaming, then I cannot be sure that I have a body.

Premise 2: I cannot tell the difference between waking and dreaming.

Conclusion: Therefore, I cannot be sure that I have a body

Employing ‘the G. E. Moore shift’, we rearrange the propositions of the skeptic’s argument, thus:

Premise 1: If I cannot tell the difference between waking and dreaming, then I cannot be sure that I have a body.

Premise 2: I am sure that I have a body.

Conclusion: Therefore, I can tell the difference between waking and dreaming.” (Preston, 2014)

Both arguments are valid, but only one can be sound. Since both accept Premise 1, the question of soundness comes down to the question of which version of Premise 2 is true.  According to Moore, we have more reason to believe the common sense premise that he has a body than the skeptical premise.

Searle himself appeals to common sense in stating his case (Searle 1995: 158).  In my view, his ‘transcendental’ argument against phenomenalist idealism (Searle 1995: 155, 183-188) could be characterized as an appeal to common sense.  Possibly Searle thinks that Moore’s ‘proof’ is not relevant to his case, but if so, it would have been useful if explained his reasons in more detail.

I think that Searle’s strongest argument in favour of his position is the one related to the main thesis of his book ‘The Construction of Social Reality’.  This argument is that the ontological subjectivity of the socially constructed reality requires an ontologically objective reality out of which it is constructed.  Or to put it simply, you cannot have institutional facts without brute facts (Searle 1995: 190-191).  For example, you cannot have the institutional fact of money without the brute fact of the metal, paper or plastic the money is made from.

A supporting (but not conclusive) argument is the consistency of realism with correspondence theory of truth, which is the idea that truth is a matter of correspondence to facts (Searle 1995: 1999).  The correspondence theory is only one of several theories of truth, but if we accept it (as many philosophers have), then it implies realism since there needs to be an external reality to which statements correspond if they true (Searle 1995: 154).

In conclusion, I think that Searle makes a good case for the existence of an external reality, both by presenting arguments of his own and by responding to the main objections to external reality.  Rather than the concept of social reality based on institutional facts presenting a challenge to external reality, I think the two concepts are consistent in the way that Searle has described.  An external reality is also consistent with the correspondence theory of truth.


[1] John Rogers Searle (born July 31, 1932) is an American philosopher and currently the Slusser Professor of Philosophy at the University of California, Berkeley.


Moore, G.E. ‘Proof of an external world’ New York: Collier Books, 1962 in Sosa, E., Kim, J., Fantl, J., and McGrath, M. (eds) Epistemology – An Anthology.Oxford: Blackwell Publishing, 2000.

Preston, Aaron. ‘George Edward Moore (1873—1958)’ in The Internet Encyclopedia of Philosophy <http://www.iep.utm.edu/&gt;, 26 October, 2014.

Searle, John R. The Construction of Social Reality. London: Penguin Books, 1995.

Torretti, Roberto. The Philosophy of Physics Cambridge: Cambridge University Press, 1999. pp 242–43

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