Peirce, like William James, is not always consistent in his remarks about truth and reality. What I present here is the “consensus theory” of truth that Pierce does, in several places, appear to advance.
The consensus theory of truth
What do we mean by truth and reality? These questions lie close to the heart of philosophy. Peirce offers some very surprising answers.
Suppose several scientists are investigating the speed of light. They use different methods and experiments. But gradually, though their answers may diverge to begin with, they will gradually close in on the same answer. The more research they do, the closer to a consensus they come, until finally, agreement is reached.
Now Peirce defines truth in the following way – it is what those who investigate a matter will all eventually agree on.
The opinion which is fated to by all who investigate is what we mean by truth and the object represented by this opinion is the real.
Note that what Peirce is offering here is not just an optimistic claim about truth – that the truth happens to be what we all end up agreeing on. He is offering a definition of truth, of what “truth” means. To say that something is true just is to say that that is what we will all eventually agree.
The suggestion that truth is, at root, whatever we agree it to be might seem open to a very obvious sort of counter-example. Suppose I manage to convince both myself and others that Earth is ruled by Lizard-people from outer space. If the truth is what ever we end up agreeing it to be, then it is true that the Earth is ruled by lizard people from outer space. But of course, this is ridiculous – we can’t just make a claim true by collectively agreeing to it, can we?
The role of scientific inquiry
Actually, Peirce’s view entails that, actually, if only we could all agree that world was ruled by alien lizards, then it would, indeed, be true. However, Pierce thinks that, as a matter of fact, the only way we will ever achieve consensus is by engaging in scientific inquiry. Why?
Well, Peirce believes that we will only agree if we collectively appeal to something independent of us. If we observe the external world, that world will impose the same kind of experiences on all of us. It forces certain experiences on us, and thereby, in the end, it forces us to agree. Without this appeal to scientific method and objective reality, no agreement will be reached.
But hasn’t Peirce now helped himself to a very different theory about truth – isn’t he saying, in effect, that beliefs are true just in case they correspond with how things stand in objective reality – the reality that forces us to agree about it over the long term? He’s not defining “truth” in terms of agreement or consensus after all, but in terms of correspondence with how things stand in this mind-independent reality.
The social theory of reality
Actually, this would be a misunderstanding. Yes, Peirce does want to say that there are “real” things and an “objective” external reality, but it turns out to be “objective” only in the sense that Peirce supposed it to independent of what any individual might take it to be. If I think the world is ruled by lizard people but no one else does, I am mistaken. For the “objective” fact is that the world is not ruled by lizard people from outer space. But if everyone were agreed that the world is ruled by alien lizards, then it would be true. Indeed, it would be an “objective fact.” Peirce offers a “social theory” of truth and reality, on which truth and reality is whatever the community ultimately agrees on. As Peirce puts it:
My social theory of reality, namely, that the real is the idea in which the community settles down.
A worry about Peerce’s theory of truth and reality
One of the tensions in Peirce’s thinking is that, once Peirce has acknowledged that objective reality is essentially social – it is whatever we finally agree it to be, it is no longer clear how it can force us to agree about it. How can it force us to agree, if its not there to force us until we agree?