## A modest theory of truth

I have previously discussed some of the problems that I have with the so-called correspondence theory of truth.  In this post, I shall suggest my own theory.

I am describing it as modest, because it does not attempt to settle all truth questions.  The use of “true” in ordinary language is a mess, and my theory will not attempt to address all such use.  Rather, it is intended only for technical uses, such as in mathematics and science.

In my last post, I made a distinction between ordinary mathematical statements such as $3+5=8$ and the axiom systems (such as the Peano axioms)  that we use to prove those ordinary statements.  There is widespread agreement on truth questions about those ordinary mathematical questions.  But there is less agreement about whether axioms are true.  Mathematics can be done, without settling questions on the truth of the axioms used.

Coming up with axiom systems is also part of mathematics.  But when a new axiom system is offered, the main concern is on whether that axiom system is useful.  Whether the axioms are true is often not asked, perhaps because there isn’t a good way to decide.  Axiom systems are usually adopted on a pragmatic basis.  That is, they are adopted for their usefulness.

Something similar happens in science.  The ideal gas laws of physics are a good example.  Those laws are true only for an imagined ideal gas.  They are false for any real gas.  But although technically false, they provide a pretty good approximation of the behavior of real gases.  And that makes them very useful.  So, with the gas laws, we see important scientific laws that are adopted on a pragmatic basis, even though they might be technically false.

The rough idea of my modest theory, is that it should deal with technical assertions where truth is important.  But it need not deal with assertions that are chosen pragmatically.

### Truth and standards

What I notice is that we often settle truth questions by appealing to standards.

If I were to say that my desk is 28.5 inches high, you would check that by measuring the height.  That is, you would apply our measuring standards to check the truth of that statement.

Similarly, if I were to say “the cat is on the mat”, you would see that as true provided that I had followed the standards of the linguistic community in the way that I used the words “cat”, “on” and “mat”.  If, instead, I described the same scene as “the cherry is on the tree”, you would think that I was crazy (see HERE for a comment on Putnam’s “cats and cherries” argument).

My theory, then:

• An assertion is true if it is consistent with the accepted community standards for judging that assertion.

Where there are no applicable standards, my theory says nothing about the truth of the sentence.

This is pretty much how we settle questions of truth in mathematics, where the axioms are the standards that we apply.  But we do not have standards as to what makes a good axiom system, so my modest theory does not tell us how to judge the truth of such axioms.

Similarly, in science, we settle questions of truth with measurements made in accordance with our measuring standards, and with our accepted scientific theories which often are the basis for those measuring standards.  But there is no standard as to what is a measuring standard, and there is no standard for a scientific theory.  So my modest theory of truth does not tell us how to judge the truth of proposed standards nor how to judge the truth of proposed scientific theories.

### Pessimistic induction

We sometimes hear a “pessimistic induction” argument criticizing science.

• All the many scientific theories that have been around for long enough, have been shown false.
• Therefore all scientific theories will eventually be shown false.

I have never much liked that argument.  With my modest theory, it cannot be applied.  For the modest theory does not judge scientific theories to be true or to be false.  Rather, it considers them to be adopted on pragmatic grounds.

As an example of this, Newton’s theories are sometimes said to have been shown false by Einstein’s theories.  However, Newtonian mechanics is still very much in use today.  It’s pragmatic value remains for most ordinary engineering tasks.

Similarly, geocentrism is sometimes said to have been shown to be false.  But we still use geocentric standards when we talk of sunrise and sunset.  If a traffic policeman stops you for speeding, his traffic ticket will list your speed in accordance with geocentric standards.

We have replaced Newton with Einstein where that makes sense.  And we have replaced geocentrism with heliocentrism where that makes sense.  But for many problems the old theories and standards are still as useful as they ever were, and we continue to use them.

### Philosophy

How will my proposed theory affect philosophy?

That’s for professional philosophers to say, but I think they won’t like it.  Quite a bit of metaphysics is engaged with truth questions which my theory declines to answer.  Personally, I think we would be better off without that kind of metaphysics, but it is not up to me decide that.

And then there’s epistemology.  As long as it is concerned with the justification of belief, I don’t think it will be much affected.  Evidence used in justification is based on standards.  And logic follows standards.

However, philosophers like to define knowledge as “justified true belief”.  And my modest theory does not admit to scientific theories as being true or false.  So they would either need to change this definition of knowledge, or stop considering scientific theories as a part of knowledge.  And I doubt that they are willing to make such changes.  For myself, I have long disagreed with taking knowledge to be justified true belief.

### Summary

I have presented a simple theory of truth, though a limited one.  Roughly speaking, it suggests that our notion of truth emerges from our adoption of standards within the community.