Commentary on Husserl's Logical Investigations, Prolegomena Chapter 3

By Jeremy Hausotter

Chapter 3: Psychologism, its Arguments and its Attitudes to the Usual Counter-Arguments

 §17 The disputed question as to whether the essential theoretical foundations of normative logic lie in psychology

The question that shapes the chapter is the following: since logic as a normative discipline requires a theoretical discipline for its essential foundation, what is this theoretical discipline? One answer is psychologism which Husserl states as “the essential theoretical foundations of logic lie in psychology, in whose field those propositions belong—as far as their theoretical content is concerned—which give logic its characteristic pattern.” (p. 90).  Husserl also quotes John Stuart Mill’s definition, which Mill said: “Logic is not a science separate from and coordinate with psychology. To the extent that it is a science at all, it is a part or branch of psychology, distinguished from it on the one hand the whole from the part, and on the other hand as the art is from the science.” In other words, logic here is the art of psychology. Psychology provides the theoretical ground for logic and logic is the practical application of psychology. Mill continues: “It [logic] owes all its theoretical foundations to psychology, and includes as much as that science as is necessary to establish the rules of the art.” (p. 90-91). 

§18 The line of proof of the psychologist thinkers

The question is now why do so many thinkers believe in the psychological grounding of logic? It begins with a simple observation, namely that whenever we define logic as a technology, we find mental activities and products to be the objects that logic regulates. Logic is concerned with “concepts, judgments, syllogisms, deductions, inductions, definitions, classifications, etc. — all psychology…” (p. 91). All of these concepts and activities involve a mental activity. “Draw the bounds of pure logic as tightly as one likes, it will not be possible to keep out what is psychological. This is implicit in the concepts constitutive for logical laws…” (p. 91). Logic as an activity necessarily involves the mind, and hence these thinkers conclude that logic has its foundations in psychology. 

§19 The usual arguments of the opposition and the psychologist rejoinder


Husserl now begins tracing out the historical debate between the psychologists and their opponents. Those who opposed the psychologist thesis reply that logic is a normative discipline. If logic was as the psychologist held, then the opponents would correctly point out that logical norms would hence be contingent and not necessary. The laws of logic are absolutely necessary and hence must be independent of psychology. 

The psychologists, Husserl notes, replies by arguing that the necessity of logical laws is a necessity of understanding, and this understanding is itself a psychological phenomena, and hence the necessity of logic must also be a result of psychology. Husserl quotes Theodor Lipps as a representative of the psychologist’s view: “We think correctly, in the material sense, when we think of things as they are. But for us to say, certainly and indubitably, that things are like this or like that, means that the nature of our minds prevents us from thinking of them otherwise.” (p. 93). We can observe a circularity in this argument for I am thinking of something as it is, but the reason behind this is due to psychology, that is, psychology is the reason for us to think that a thing is as it is. 

The opponents object that presentations, judgments, syllogisms, etc. certainly have a place in psychology, but the relationship between them and psychology is distinct from that between them and logic. Psychology investigates the “laws governing the real connections of mental events with one another, as well as with related mental dispositions and corresponding events in the bodily organism.” (p. 93). These connections are causal and necessary. Logic, on the other hand, is not concerned with the causal origins of mental activities nor their effects; rather, logic investigates truth-content, true and false judgments. The logician is not concerned with real connections, but ideal ones. Remember that what Husserl means by “ideal” is an object outside space and time whereas “real” refers to something within space and time. For Husserl, the logician “aims not at a physics, but an ethics of thinking” (p. 94). The psychologist would reply that logic as a technology of knowledge requires psychology to explain the causal connections. Husserl says more about the historical debate, but we need not concern ourselves with it.        


§20 A gap in the psychologist line of proof

After his recounting of the historical debate, Husserl asked “Have the arguments of the psychologist thinkers really settled this?” (p. 96). That is to say, has the psychologist account sufficiently accounted for the phenomenon of logic? The fact that there was a debate at all if the psychologist view is so obvious Husserl notes is a source of “philosophical wonder”. Husserl concludes from this summary of the historical debate over psychologism that the psychologists only proved that “psychology helps in the foundation of logic, not that it has the only or the main part in this, not that it provides logic’s essential or main part in this, not that it provides logic’s essential foundation in the sense above defined.” In other words, psychology has nothing to do with the essence of logic. In the previous chapter Husserl argued that normative disciplines required a theoretical discipline as the essential foundation for the construction of normative disciplines. Psychology does not have this role as a theoretical discipline for the construction of logic. This is the main conclusion we need to take away from this chapter. 

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