Commentary on Husserl's Logical Investigations, Prolegomena Chapter 6

By Jeremy Hausotter

§30 Attempts at interpreting syllogistic principles psychologistically

Husserl is now going to briefly transition to the problem of psychologism in reference to syllogisms. The previous chapter he spent investigating the psychologistic consequences to the law of noncontradiction, so now his attention is on syllogisms. 

Husserl begins with a sort of reflection on psychologism. He states that “The thought-motives that push our thinking in this direction have, in fact, a strong air of obviousness.” (p. 129). Psychologism has a pseudo-obviousness that provides its credibility. Some philosophical theories like psychologism are not really philosophical nor intellectual, but are merely a false air of scholarly pretense that lulls the mind into unquestioning assent. Alice von Hildebrand wrote a penetrating analysis on the phenomenon of the pseudo-obvious and you can read it here

Husserl notes that the psychologistic interpretation of syllogisms is not often explored since syllogisms are deductive results of the axioms of logic. Nevertheless, there are objections to be made against the psychologistic interpretation. For example, fallacious inferences and logical deductions should alone be sufficient to demonstrate the difference between syllogisms and psychological laws. When we condemn a fallacious inference, we do so based on the principles of logic, not psychology. If the framework for our objections were psychological, then we would not be concerned with fallacious thinking, but abnormal thinking. Fallacy, truth, and logic are all interconnected, whereas the question of abnormality in one’s mental constitution is properly psychological. 

Syllogistic deductions, Husserl observes, always possess the status of laws. Psychological laws are laws of an entirely different kind, “laws” in a wider sense which are not apodeictic. The difference between the lawfulness of syllogisms versus psychological laws are “toto caelo” (ibid). 

Interestingly, the psychologistic logician Heymans was unconcerned by the existence of fallacious arguments, arguing that their existence is proof for his views. Husserl reminds us that we must keep in mind the distinction between logical and psychological incompatibility. Fallacious arguments are logical errors and incompatibilities. The same mind can make both fallacious and valid arguments, but that mind does not possess psychological incompatibility until he or she realizes the error in the argument. The unnoticed error is not an error on the purely psychologistic view, for psychological and logical incompatibility are equated on the psychologistic model. As Husserl remarks:


One might well ask whether contradictions that pass unnoticed are not genuine contradictions, and whether our logical law merely affirms the impossibility of unifying contradictions to be jointly true. Again, one need only reflect on the difference between psychological and logical incompatibility, to be quite clear that we are once more lost in the thick fog of the aforementioned ambiguities. (p. 130).


The critical observation is that “no psychological law connects a refutation with a fallacy.” (ibid). One can have logical judgments, but as psychological phenomena they do not connect bring us to the realization of a fallacy. It is the laws of logic by which we are informed of the erroneousness of an argument. 

A fallacy can enter our consciousness many times without our recognizing it as such. It is only through the rigors of logic that we realize the falsehood of the fallacy. In other words, fallacies can coexist with acts of judgments and this psychological fact should convict us of the impossibility of equivocating psychological and logical incompatibility. Under the psychologistic interpretation,

Self-evidence and blind conviction, exact and empirical generality, logical incompatibility of states of affairs and psychological incompatibility of acts of belief, impossibility of joint truth and impossibility of joint belief, all run together. (p. 131). 

§31 Syllogistic and chemical formulae

Heymans compared logical formula to chemical formula. Both are subject to experimentation and repeated experiments compel us of its necessity. He appealed to the notion of “irrefragable necessity”, which is a necessity that “compels us to affirm the conclusion when we have conceded the premisses.” (p. 132). 

Husserl’s reply to this “irrefragable necessity” is by making a distinction. He observed that all syllogisms, whether logically justified or not, come with a psychological necessity and feeling of compulsion. What needs to be distinguished therefore is “felt irrefragability” from “real irrefragability” (cf. p. 132). The first is psychological, the second grounded in the laws of logic and of genuine logical necessity. Real irrefragability arises as a result of insight into the syllogism and hence there is an insight into the necessary validity of the matter at hand. It is a validity grounded in the logical laws. 

Another reply Husserl gives is that in a chemical formula we know the circumstances for why hydrogen and oxygen are transformed into water, but we do not know the circumstances that leads us to syllogistic formula. Any psychological circumstances cannot be exactly defined, but always retain a nebulosity. 

In conclusion Husserl repeats his distinction between psychological and logical incompatibility, except now he calls the latter “ideal incompatibility” (p. 134). This is not an empirical reality for the ideal incompatibility of a syllogism is of universal validity. We must keep in mind valid syllogisms express truth and fallacies falsehoods. The empiricist, on the other hand, cannot arrive at this judgment. He “cannot give this answer.” (p. 132). Empirical and psychological grounds alone is an improper research methodology alien to logic as a science. These methods cannot bring us towards the inner eidos of logic. 

I now want to make a note of some notation that may be hard for the reader. On pages 131-132 Husserl and Heyman use symbols such as MaX, YiX, and XeM. These refer to the four kinds of Aristotelian propositions. They are universal affirmative (a propositions), eg, all labradors are dogs, universal negative (e propositions), eg, no cats are dogs, particular affirmative (i propositions), eg, some pets are dogs, and particular negative (o proposition), eg, some pets are not dogs. In the proposition MaX then, M refers to the subject, X is the predicate, and the a refers to the type of proposition. Hence MaX means “all M are X”. Similarly, YiX means “some Y are X”. For the interested reader, you can read more about this here.

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