Epistemology: Kant and Theories of Truth

I. The debate between empiricists and rationalists prompts Immanuel Kant (1724-1804) to highlight differences between the kinds of statements, judgments, or propositions that guide the discussion.

For Kant, the distinctions between analytic and synthetic and a priori and a posteriori judgments must be kept separate, because it is possible for some judgments to be synthetic and a priori at the same time. What Kant proposes is this: Surely all a posteriori judgments are synthetic judgments, since any judgment based solely on experience cannot be derived merely by understanding the meaning of the subject. But this does not mean that all synthetic judgments are a posteriori judgments, since in mathematical and geometrical judgments, the predicate is not contained in the subject (e.g., the concept 12 is not contained either in 7, 5, +, =, or even in their combination; nor does the concept "shortest distance between two points" contain the idea of a straight line). Such propositions are universal and necessary (and thus a priori ) even though they could not have been known from experience; and they would be synthetic a priori judgments.

If there are such judgments, then how are they possible? Kant's answer: the rationalists are right in saying that we can know about things in the world with certainty; and the empiricists are right in saying that such knowledge cannot be limited merely to truths by definition nor can it be provided by experience. Instead, we know about the world insofar as we experience it according to the unchanging and universally shared structure of mind. All rational beings think the world in terms of space, time, and categories such as cause and effect, substance, unity, plurality, necessity, possibility, and reality. That is, whenever we think about anything, we have to think about it in certain ways (for example, as having causes, as existing or not existing, as being one thing or many things, as being real or imaginary, as being something that has to exist or doesn't have to exist), not because that is the way the world is, but rather because that is the way that our minds order experience. There can be no knowledge without sensation, but sense data cannot alone provide knowledge either.

We can be said to know things about the world, then, not because we somehow step outside of our minds to compare what we experience with some reality outside of it, but rather because the world we know is always already organized according to a certain fixed (innate) pattern that is the mind. Knowledge is possible because it is about how things appear to us, not about how things are in themselves. Reason provides the structure or form of what we know, the senses provide the content.

Objections to Kant:

• We can never know anything about things we do not experience and organize in terms of the mind's structure--for example, God, soul, and other metaphysical topics; and that seems a shame.
• Kant's solution means that we will never know if our ideas about the world are true; or it means that we have to redefine reality as that which we experience rather than that which experience represents. In short, if we are limited to phenomena (things as they appear), either we will never know if our ideas are true or we have to redefine what truth is.
• If Kant is right, then why do cultures seem to differ on the categories of understanding? One possible is that even though the categories seem to vary, such differences are due only to differences in the "surface grammar" of language, the ways in which things are understood as meaningful. When asked why languages are structured in certain ways, some theorists claim that the brain and our neural networks form the "deep grammar" of what things mean.

III. The second objection above to Kant raises the question: What does it mean to say that a proposition is true? There are three main theories of truth:

• Correspondence theory of truth: a statement or belief is true if it corresponds to the facts. Truth is thus a property of a statement. The facts exist independently of our knowledge of them. Accurate observations can report actual states of affairs and cannot result in reasonable disagreement. Einstein and other "scientific realists" (proponents of the view that theories are true if they describe reality) endorse this idea and claim that our task is to find out the truth about nature, even if that means changing the basic presuppositions of our theories.

Problems:

• How can we know whether our perceptions are correct? What justification/reasons do we have for a belief? This changes the notion of truth away from a property of a statement to the reasons we provide for beliefs. But then, how can we know whether our beliefs about the facts are justified? We cannot know the world apart from our knowledge.
• Besides, what about truths that correspond to no particular "facts" (e.g., philosophic principles, scientific theories like evolution, love, justice)?
• And how do we tell whether generalizations are adequate?
• Coherence theory of truth: Since the only way to know something is by appealing to beliefs, that which is true is that which is consistent with our overall network of beliefs. A claim is true if it meets the requirements of science (simplicity, comprehensiveness, predictive). This position is supported by philosophers of science Karl Popper and Thomas Kuhn, who support this view because, they argue, there is no one truth because there is nothing "really out there."

Problems:

• Beginning assumptions cannot be proved, so what if the whole network is wrong?
• Why can't equally coherent and seemingly acceptable systems be reconciled?
• Pragmatic theory of truth: A statement is true IFF (if and only if) it would satisfy our expectations were we to act upon it. That is, the consequences of being able to integrate knowledge, predict events, achieve goals determine whether a belief is true. Truth is thus a function of human endeavor, not some existence apart from us. This theory of truth supports a view of science called instrumentalism, which argues that theories are instruments that are useful for calculating and predicting. According the physicist Niels Bohr, this is especially applicable in quantum theory.

Problems:

• If what is effective can change, so can the truth. But truth should be constant.
• Just because something works (for us) doesn't make it true. For example, if we tell a small child that if she goes into the street the boogeyman will get her (in order to prevent her from being hurt), the success of our lie in protecting her does not make what we said true. Besides, the reason something works is that it is true, not the other way around.