Psychologism,
according to the Stanford Encyclopaedia of Philosophy, is a term used by
authors to refer to “what they perceive as the mistake of identifying
non-psychological with psychological entities,” (Kusch Preface). Frege uses the
term, more specifically, to refer to the mistake of treating logic as a special
branch of psychology. It is important to realize that the psychologistic
viewpoint is no single argument, nor can it be effectively dismissed by
refuting any one argument. Rather, the psychologistic viewpoint is several arguments
brought together by common assumptions, each one bringing out the implications
of a certain element in those assumptions. Over the course of this paper, we
will examine the strongest arguments in favour of the psychologistic viewpoint
and Frege’s response to each of these arguments. Each of these responses will
draw out a distinction in Frege’s own philosophy of logic. The strongest
arguments in favour of psychologism can be summarized as: the inseparability of
logical and non-logical reasoning, the indemonstrability of primitive laws and
the limits of thinking, the a posteriori nature of justified belief and, lastly,
the mental subject matter of logic. Frege’s responses will call our attention
to: the timeless nature of logical truths, the necessary conditions of
objective truth, the meaning of logic as a priori knowledge, and finally the
distinction between thought and idea.
To
begin, we should understand that logic as a mental process of inference is
therefore a human activity and so exists within a socio-historical context. Reason
has a special and oppressive place within this context to which we should not
be blind. Since Plato, Reason has been tied to both legitimizing power and
making it exclusive in both explicit and implicit ways (Plumwood 11). Formal
logic claims an absolute and timeless Truth void of both the oppression it
exists in and the emotional attributes it thereby devalues (Plumwood 13).
Consequently, it denies the experience of the oppressed as being unimportant to
considerations of Truth. Logic also excludes the oppressed through its abstract
notation, which requires background knowledge (i.e. university training or
equivalent time expenditure) to which they would not have access. When logic is
not in this power-laden abstract form, it is in the form of natural languages
whose meanings and histories (of oppression) are inextricable. The very attempt
to claim that logic does not suffer from the impurities of psychology, is a
power-claim that must be understood in terms of its psychological-sociological
context. Logic is therefore inseparable from psychology. The force of the above
criticism comes from its appeal to a “common sense” association between logic
and the elite environment in which it was developed. By questioning the
intentions (conscious or otherwise) of those who do logic, the critic sidesteps
logic as a subject matter and instead treats logic as an activity, which seems
to only logically result in a psychologistic view of logic.
This first
criticism is a point Frege indirectly addresses in the introduction to “The
Foundations of Arithmetic”. If we were to treat logical-mathematical truths as
subject to socio-historical contexts then “astronomers would hesitate to draw
any conclusions about the distant past, for fear of being charged with
anachronism,” (Frege Foundations VI). No matter how “Reason” may be
abused over the course of history, the truths it ascertains are of a timeless
nature. If they were not, then (as Heraclitus made clear) everything would be
in flux and we could not know anything about the world (Frege Foundations
VII). This response draws its strength from taking the very existence of
knowledge as one of its premises, something no opponent can do while simultaneously
maintaining a commitment to the objectivity of their own claim.
To this, critics
from the oppressed groups can say, “At no point did we deny that there are
timeless truths, we’ve only denied that one can effectively isolate them from
contextual truths of oppression. Is the totalizing nature of your system not
evidence of a bid to ignore the conditions of the oppressed?” Frege answers
this question in his division between two kinds of proof. The first kind relies
on the laws of logic alone, whereas the second also requires additional
empirical facts (Frege Begrift. 103). Though the language of “purity”
may misleadingly suggest some kind of normative superiority in the strictly
logical kind of proof, in fact, these are simply two different kinds of proof.
Claiming that logical proofs can exist alone no more devalues emotionality,
than excluding ballet from biology devalues dance. Frege’s point is simply that
such considerations are misplaced in his project. To criticize Frege’s logical
language for failing to capture these everyday facts would be like blaming a
microscope for failing to be a pair of eyes (Frege Begrif. 105). We can
conclude from this that not only is it not necessary to appeal to
socio-historic conditions when undertaking the study of logical truths, but, in
fact, it is detrimental to that study. The first criticism is therefore refuted
and the necessarily timeless nature of logical truths asserted.
Secondly,
we may ask Frege what the origins of his logical rules are. He might respond
that we have merely to examine our own thoughts to realize that everything we
think (when we are thinking correctly) has a certain underlying structure. If a
black board were nearby, he may write “x=x” and ask us if we disagree. No, but
not because we can prove that “x=x” would always be the case in every possible
world, but because we cannot imagine a world being otherwise. Indeed, if the
final appeal in logic is always to limits on imagination and what we intuit to
be true, if there are no further steps possible to prove the basic concepts of
logic, then the limits of logic are the limits of thinking and that is very much
a psychological topic. The force of this criticism lies in its appeal to the
principle of sufficient reason ad infinitum. If something is being held as
true, we as rational creatures want to know what reason we have for holding
that. We then ask what reason we have for holding those reasons, etc. Stopping
the justification seems to be necessitated by personal rather than objective
rational limitations.
Frege makes it
quite explicit in the introduction to the “Foundations” that his project is to
ground mathematics in logical laws “which themselves neither need nor admit of
proof,” (4). In a footnote he argues that the existence of any general truths
at all necessitates the admission of such “primitive” laws, since, without them,
we would never have any justification for believing anything--only procedures
which induce belief (Foundations 4). If we must have these laws, let us
then ask what kind of laws they are. We can understand these laws two ways.
Firstly, “the laws” could mean that there is a certain reality external to the
subjectivity of the thinker which limits what that thinker can think. Secondly,
“the laws” might mean something inherent to the subjectivity of the thinker. To
analogize: in the first case, the laws of thought are walls beyond which
nothing sensical is, whereas, in the second case, there is merely a horizon
which our eyes cannot see past. It is clear that the critics mean the second
case.
If these basic
laws are of the second kind, then the critics are right in concluding that
logic is therefore a topic of psychology. Frege makes it very clear in his
Thought paper that the basic laws are of the first kind. He says to mistake the
laws of thought for the laws of thinking is to ignore the fact that what laws
tend to is truth, whereas the laws of thinking would have to account for how
one comes to error and superstition as well (290). Said differently, the
logical laws deal with thought, which are objective logical entities, whereas
the psychological laws deal with ideas which are subjective mental entities
(Frege Thought 291-92). Thoughts are things for which the question of
truth and falsity arise, whereas ideas are simply subjective mental
occurrences. Even if it were the case that our minds only tended towards truth,
to equate logical with psychological laws would be “to take a description of
the origin of an idea for a definition,” which we should never do (Frege Foundations
VI). After all, “an explanation of a mental process that terminates in an
assertion can never take the place of a proof of what is asserted (Frege Thought
290). This becomes clear in the following analogy:
Suppose
Bartholomew wants to get to his girlfriend, Truth’s, house. He walks west for a
few blocks, then turns north a few more blocks. He passes three orange bushes and
a one-eyed man playing a bronze tuba. He catches a bus going east at 60 miles
an hour for fifteen minutes. Eventually, he arrives at a house. Do we, as the
observers, know if it is the correct house? No.
No matter how
excruciatingly detailed we are in our description of the steps Bartholomew
takes to get to his girlfriend’s house, that alone could never indicate to us
whether or not Bartholomew has arrived at the correct destination. If we are
interested in knowing if he has arrived at the correct house, we must know
something else, the correct path. Similarly, the laws of psychology describe
how people take the steps people actually take to get to their particular
mental destinations. These laws tell us nothing of whether or not the path was
correct. It is the correctness of the path which logic is interested in,
whether or not anyone ever takes it, or how they do is irrelevant to logic’s
subject matter. We can therefore confidently reject the critic’s equivocation
between the laws of thought and the laws of thinking. The second criticism is
therefore refuted. As a result, we gain a more solid notion of the true subject
matter of logic. It is “the path” inference, not as it happens to be taken by
people (as a mental activity), but as it must be taken in order to reach the
correct destination.
The
third argument is perhaps the most historically grounded. Both John Locke and
John Stuart Mill, at different times, have argued against the idea that a
priori knowledge is possible. Locke argues that if any logical truths were
really prior to observation, then children would readily admit them, but it is
only after a certain abstract learning process in the world that these truths
become known (273). What is important about this abstract learning process is
that it must begin with concrete objects and observation and develop from there
(Locke 273). Similarly, Mill argues that proof for believing in axioms consist
in generalizing from observations (Kusch Sec. 2 Par 11). Perception and
observation become indispensable for the proving of logical truths. Observation
is unquestionably a topic for psychology, therefore logic, again, must look to
psychology for its foundations. The strength of this claim rests on similar
grounds to feminist critique. That is, the seemingly highly contrived and
abstract nature of logic seems impossible to identify with anything other than
a human activity, an impressive mental feat.
Given that truth
is the aim of logic, logic must study whatever truth can be discerned from
(Frege Mind 289). If truth and falsity were either physical objects or
properties of physical objects then Locke and Mill would be correct. The
question then arises, is truth (or falsity) a physical object or a property of
physical objects? Is it possible to discern truth through the senses? Frege
considers this possibility that truth comes to us from the senses in his
Thought paper, quickly rejecting it (292). After all, if truth/falsity were
properties of objects then it would make sense to say “the sun is true” in the
same way that we might say “the sun is bright” or “the sun is a holy hippo”
(Frege Thought 292). It does not make any logical sense to say “the sun
is true” (though we might mean it poetically somehow). It does make sense,
however, to say “the sun is bright” or “the sun is a foul-smelling bus
passenger”.
Now we must ask:
what does it mean for a sentence to make or have a sense? The answer to this
question will make very clear the difference between the first sentence, “the
sun is true,” and the others. According to Frege, “It is for the sense of a
sentence that the question of truth arises…” (Frege Mind 292). This
means that if a sentence has a sense, it must be possible to ask whether the
sentence is true or not. Frege does not merely mean the sounds that make up the
sentence, since sounds are no more true or false than the sun. It is what the
sentence expresses that is true or
not; what it expresses, Frege calls a “thought” (Frege Mind 292). At the
risk of sounding slightly redundant, it is important to see that if we cannot
ask whether a sentence is true or not than that sentence must not express a
thought. Truth and falsity are therefore not properties of physical objects,
but rather prompted by non-physical “thoughts”.
Let us return
then to our original challenge and see what becomes of Locke and Mill’s claim.
They say that physical objects must be observed in order to discern any truth
(which is what logic attempts to do).We have already established that this is
not true in any direct way because truth and falsity are neither physical
objects themselves nor properties of objects (the sun cannot be true or false).
Frege responds that truth and falsity are not properties of objects, but rather
have to do with the thought a sentence expresses (which is a non-physical
thing). Locke and Mill return that the thought needs to be about something and what it must be about are all physical objects.
A logical statement expressing the thought “x=x” may refer to any physical
object in particular, but, because of that fact, refers to no physical object
in particular. What’s more, the truth of the above statement is made no more
certain no matter how many particular objects are given as evidence. It follows
solely from primitive logical laws which, according to Frege, make it an a
priori truth (Foundations 4). Even if the sentence did pick out a
particular object “that tree is that tree” it would be no less an a priori
truth, since, according to Frege “these distinctions between a priori and a
posteriori… concern… not the content of the judgement but the justification for
making the judgement,” (Foundations 3). Locke’s insistence that children
must learn these rules through sensory examples is not a problem for Frege
since the origin of a belief is not the same as what proves that belief (in the
same way that describing the path to a location, on its own, tells us nothing
of whether the location is the desired one). In this way,
the third criticism is safely refuted.
Lastly,
there is the argument that logic’s abstract “objects” are mental entities and
so naturally fit into the purview of science. “1. Logic is the theory of
judgments, concepts, and inferences. 2. Judgments, concepts, and inferences are
human mental entities. 3. All human mental entities fall within the domain of
psychology. Ergo, logic is a part of psychology,” (Kusch Sec. 3 Par. 4). This
argument is perhaps the most intuitive, since all three premises seem, at least
at face value, uncontroversial. Indeed, the very need to argue against any of
these premises would lend credence to Locke’s argument which relies on the need
to perceive logical laws, rather than simply having always known them. The less
obvious logical laws are, the more difficult it is to claim that they are
somehow independent of the very particular (often academic) experience which
creates them.
The last
criticism, that logic is about judgements, concepts and inferences, these are
all human mental entities, therefore logic is a subcategory of psychology has
largely already been answered in past refutations. For clarity’s sake, however,
we will examine this argument in its own right. It is clear that premise 1
“Logic is the theory of judgments, concepts, and inferences” is uncontroversial
(Kusch Sec. 3 Par. 4). Logic does indeed cover all of these concepts and Frege
himself discusses them quite plainly (Thought 294). Given this, it must
either be premise 2 or 3 which are false, since the argument is itself
seemingly valid. Judgements, concepts and inferences, it has already been shown
cannot simply be mental entities in the same way that superstitions or emotions
are since this would make the truths of math subjective (Frege Foundations
VI). Logic does not study the judgements, concepts and inferences as mental
occurrences (though they are sometimes), in the same way that the physicist
does not study physical laws as experience, but as an independent subject
matter. If we were incapable of distinguishing between the physical experience
and the objective laws underlying and governing that experience, than physics
to would be a branch of psychology. In fact, along this line of reasoning, everything
would be reducible to psychology. This argument for psychologism is the
broadest in scope, but for that reason goes too far in equivocating that which
is both necessarily and sufficiently described as a mental entity (i.e. that
which is essentially a mental entity) and that which need not be described in
terms of a thinker (i.e. that which is only accidentally a mental entity). It
is clear from the above that disciplines such as logic and physics which deal
with the second kind of subject matter. The fourth and final criticism is
therefore refuted.
To conclude
briefly, I would like to make plain the errors common to multiple or all
psychologistic arguments explored in this paper. All arguments to a greater or
lesser extent confused the objective thinker-independent subject matter of
logic with either the thinker-dependent experience of that subject matter (e.g.
the learning of it) or else reducing it to thinker-dependent “ideas”. The
strength of the criticisms lied mainly in their intuitive appeal to how one may
feel about logic, but these arguments lacked the sophistication in distinction
necessary to critique Frege’s true project. The recurrent appeal to the
seemingly contrived nature of logic can be said to be the underlying motivation
for all these criticisms and relies on a confusion between the form and content
of logic.
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