The Impossibility of a Validity Criterion, Part Three

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In my last two posts, I’ve been summarizing and making comments on Leonard Nelson’s paper “The Impossibility of the ‘Theory of Knowledge.'” In the part I covered in my first post, Nelson argued that a validity criterion for proving the objectivity of cognition is impossible, successfully in my view. In the part I covered in my second post, Nelson attempted to analyze why there cannot be such a validity criterion. This post will cover the last part of Nelson’s paper, where he outlines a new project for psychology and defends it philosophically – I am skipping a lot of the paper here because I found certain parts less interesting.

Nelson finishes up his paper by pointing to a distinction between two kinds of knowledge: “reflective knowledge” (i.e., introspection) and “intuitive knowledge” (i.e., sensory perception). This distinction, which Nelson will end up rejecting, is allegedly exhaustive of all knowledge. Nelson thinks that if we accept this distinction, then we have only three ways of accounting for our metaphysical knowledge (metaphysical knowledge includes beliefs like the law of cause and effect, which are fundamental but difficult to justify):

  1. Metaphysical Logicism: Metaphysical knowledge comes from reflection.
  2. Metaphysical Mysticism: Metaphysical knowledge comes from intuition.
  3. Metaphysical Empiricism: There is no metaphysical knowledge.

Nelson thinks he has knockdown arguments against metaphysical logicism and metaphysical mysticism. He presents them briefly in the following passage:

Logicism, such as formed the basis for scholastic metaphysics and which has been revived in the “theory of knowledge,” breaks down on the psychological fact of the indirectness and emptiness of reflection.┬áReflection can analyze and elucidate cognitions elsewhere provided but cannot of itself creatively beget new cognitions, that is to say, it is a source only of analytic, but not of synthetic, judgments.

Mysticism, such as forms the basis for neo-Platonic mysticism in its old and new forms, breaks down on the psychological fact of the original obscurity of metaphysical knowledge. There is no immediate obviousness in metaphysical truths; we cannot derive these cognitions from an ‘intellectual intuition’; they reach our consciousness only through thinking (reflection), though abstracting from the intuitively given content of empirical judgments.

I don’t think Nelson takes these positions as seriously as he should. Specifically, he overlooks a form of metaphysical mysticism (the term “mysticism” is pejorative and distracting, which may have been why Nelson overlooked a more reasonable form of it) which just says that we learn about causality by, first, observing causality in thousands of concrete instances, then, second, abstracting from these concrete cases of cause and effect to the general principle. This account has it that we acquire metaphysical knowledge through sensory perception or “intuition,” so it qualifies as a form of metaphysical mysticism by Nelson’s definition, but it is not defeated by his objection to metaphysical mysticism. Nelson does have a potential response to this objection, which I’ll discuss after the necessary context has been provided, so this is not a conclusive objection by any means, but it does seem like an oversight on Nelson’s part.

After rejecting logicism and mysticism, Nelson considers metaphysical empiricism, the view that we don’t have any metaphysical knowledge. Nelson’s example of a metaphysical empiricist is David Hume, who thought that, for example, our belief in causal connections was due to instinct and custom rather than evidence.

Nelson’s response to metaphysical empiricism is to issue the metaphysical empiricist a challenge: “His [Hume’s] task then became not that of verifying the metaphysical judgments but that of explaining psychologically the illusion that calls forth these judgments, i.e., of explaining how the claim to knowledge asserted in these judgments is possible without presupposing an actual source of knowledge, merely as a product of the blind mechanism of the association of ideas. The question now arises whether this task is capable of fulfillment.”

It is worth noting that a metaphysical empiricist is not necessarily obligated to undertake this task. For one thing, he may not believe that our metaphysical judgments are the product of “the blind mechanism of the association of ideas,” specifically. He may have some other mechanism in mind. He might also refuse to provide an account of our metaphysical ideas in any terms, on the grounds that one need not explain why we hold an unjustified idea to reject it. Still, I think Nelson’s challenge is reasonable.

Nelson next explains why he thinks the association of ideas cannot explain our idea of causality:

Hume believed that he could find the basis for the judgments that were the object of his problem in the psychological principle of the expectancy of similar cases. But he was not unaware of the difficulty to be encountered in basing this principle on the laws of association. Association explains only that event A reminds me of a previous event B connected with it, but not that I expect the reoccurrence of B. The remembered thought, as such, is only problematic, whereas expectation comprises an assertion which – whether it be one of certainty or only of probability – cannot be explained by association alone. Hume tried to overcome this difficulty by presenting the difference between problematic and assertoric notions as merely one of degree, basing this difference on a difference in the intensity of the clarity of the notions. On this supposition our recollection would, indeed, after sufficiently frequent reproduction, be able to pass over into an expectation merely through the effectiveness of the association. But this Humean hypothesis, that the difference between problematic and assertoric notions is only one of degree, contradicts the facts of self-observation. This is generally admitted today; and so Hume’s attempted solution collapses.

This argument has two problems. First, Hume might see it as question begging, because Nelson does not provide a conclusive reason why association cannot give rise to expectation. Second, it only deals with Hume’s explanation of our belief in the law of┬ácausality, not with other metaphysical empiricists’ explanations of the law of causality or Hume’s attacks on metaphysical beliefs other than the law of causality.

Since metaphysical logicism, mysticism, and empiricism all fail in Nelson’s view, we have to reject the initial dichotomy between knowledge by reflection and knowledge by intuition. According to Nelson, we must have another kind of knowledge, which he calls “nonintuitive immediate knowledge.” Nelson calls this fourth view on how we acquire metaphysical knowledge “metaphysical criticism.” Nelson thinks that the basis for this kind of knowledge is the “immediate cognition” that I mentioned in part two. Since the basis for this kind of knowledge is immediate cognition, it is not appropriate for philosophy to investigate how we know it – that is the job of psychology.

We can now see how Nelson might respond to the possibility I mentioned earlier about learning the concept of causality through abstraction from thousands of concrete cases. He might say that this is not a mystical theory but a critical theory that attempts to investigate the psychological basis for our knowledge of causality. I don’t think it’s unreasonable to make that argument, but I’m not quite sure if introspecting and finding a plausible account of how we form the idea of causality, which is all that is necessary to arrive at the conclusion that we abstract causality from thousands of concrete cases, qualifies as psychology.

All in all, this has been a very interesting paper and I learned a lot by reading it.


The Impossibility of a Validity Criterion, Part Two

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In my last post, we saw how Leonard Nelson argues that a theory of knowledge is impossible in his paper “The Impossibility of the ‘Theory of Knowledge’.” Next, Nelson gives an analysis of why the project of constructing a theory of knowledge turned out to be impossible. (He claims to be following Kant’s method of analyzing the presuppositions of a problem before trying to solve the problem itself.)

The first step Nelson takes is to point out that “theory of knowledge” assumes that the validity of cognition is questionable. I think what he means is that projects like Descartes’ attempt to prove the validity of sensory perception assume that sensory perception is capable of being questioned in the first place. (The point is broader than just attempts to prove the validity of sensory perception, though.) So Nelson wants to investigate this assumption that anyone can question the objectivity of cognition.

Nelson identifies the assumption that we can question the objectivity of cognition as an instance of the “logical principle of sufficient reason, according to which every assertion needs a verification.” Nelson seems to be thinking of verification as justification, i.e., some sort of prior reason to think that the assertion is true. Since not every assertion can be proven by reducing it to other assertions, there must be a method of verification in addition to proof.

What method might this be? Nelson claims that, in addition to the combinations of concepts which are judgments, we also have immediate, non-conceptual perceptual knowledge. We combine concepts into judgments and try to get them to match our perceptions. While it is not guaranteed that our judgments will match our perceptions and therefore be true, it is guaranteed that our perceptions are veridical – indeed, perception cannot be questioned as such.

To summarize, I think what Nelson is saying is that the “theory of knowledge” gets into trouble because it ignores the possibility of a criterion of knowledge which is validated, not by reducing it to other propositions, but by direct perception. If that is what he is saying, then I’m not sure why he isn’t just running into the same problem he set for the “theory of knowledge”: To know that direct perception is a valid source of knowledge, he would have to directly perceive that direct perception is a valid source of knowledge, which presupposes that direct perception is a valid source of knowledge. So, it will be interesting to see what Nelson has to say about that, if anything.

I should also add that I do not see how Nelson has proven that the validity of cognition is not questionable. He has asserted that we have perceptual judgments which are unquestionable, but this seems question begging against the “theory of knowledge” that he is criticizing. It’s possible that he will defend this claim later in his paper.

The Impossibility of a Validity Criterion

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In his article “The Impossibility of the ‘Theory of Knowledge,'” Leonard Nelson presents the following argument against the possibility of a validity criterion by which we could “test the truth or objective validity of our knowledge.”

In order to solve this problem, we should have to have a criterion by the application of which we could decide whether or not a cognition is true; I shall call it briefly the “validity criterion.” This criterion would itself either be or not be a cognition. If it be a cognition, it would fall within the area of what is problematic, the validity of which is first to be solved with the aid of our criterion. Accordingly, it cannot itself be a cognition. But if the criterion be not a cognition, it would nevertheless, in order to be applicable, have to be known, i.e., we should have to know that it is a criterion of the truth. But in order to gain this knowledge of the criterion, we should already have had to apply it. In both cases, therefore, we encounter a contradiction. A “validity criterion” is consequently impossible, and hence there can be no “theory of knowledge.”

My interpretation of this passage is that Nelson is making the following argument.

  1. A validity criterion must be proven.
  2. The only way to prove the validity criterion would be to apply it to itself.
  3. No argument that takes a criterion as a premise is a proof of that criterion.
  4. Therefore, there cannot be a validity criterion.

The conclusion follows deductively from the premises, so the question is whether the premises are true. Premise 1 is a standard assumption in theory of knowledge, according to Nelson – it’s the position he’s attacking, not a substantial assumption on his part. Premises 2 and 3 seem to follow from the definition of a validity criterion and the definition of proof, respectively.

At least initially, I think this is a good argument against what Nelson is calling theory of knowledge. It’s worth pointing out, however, that not everything in traditional epistemology counts as theory of knowledge in Nelson’s sense (and Nelson would hasten to agree).