While Wolffian
school had relegated the question of truth to the practical or
applied side of logic, Hoffmann understood its value and insisted
placing it in theoretical side. Corresponding with this exalted
place, Hoffmann's actual investigation of truth is surprisingly
thorough, even if it ultimately fails as a reliable evidence for
truth.
First of all,
Hoffmann delineates the topic by noting that we are not speaking of
moral truth, which means correspondence of a speech or writing with author's intentions. Instead, it is truth as the correspondence
of one's actual thoughts with actual things that Hoffmann has in
mind. Furthermore, this subjective truth is dependent on still
further notion of objective truth or correspondence of possible
thoughts with actual things – this objective truth, Hoffmann says,
is reducible to the notion of reality or actuality.
Hoffmann notes the
paradoxical nature of ascertaining the possibility of objective
truth. Such ascertainment can only happen through some general proof,
but it is just these human tools of proof that are in question in
this investigation. Human ability of deduction or inference must then be applied
to itself in order to show its own validity, which makes the whole
endeavour rather circular. Hoffmann notes that this is just inevitable
and even distinguishing feature of all basic principles – proofs
for them must be of completely different sort than proofs of common
propositions.
The first and
foremost task is to investigate the formal principles by which human
beings prove things – that is, what we would call rules of
inference. We already know that we feel forced to accept these rules,
but this does not mean that the rules would work also with actual
things. It is the explicit task of the three highest principles to
provide this required link of ideas with things, while other
principles might just connect ideas with one another.
Beginning with the
highest principle of non-contradiction, Hoffmann notes that the only
way to justify it is to show how impossible it would be to think
against it. Suppose we consider the proposition ”something both is
and isn't”. This proposition must be accepted as either true or
false, both true or false, neither true or false or epistemically
uncertain. The last possibility can be ignored, since uncertainty
concerns only the status of a thinker and not the proposition itself.
We are then left
with four options, of which we would like to show the falsity to be
the most convincing. We cannot really state that the proposition would be
both true and false, since we cannot understand what that means. If
we accepted that it is neither true or false then the proposition
wouldn't even be a proposition, which must always be either one –
and we would have nothing to think about at all. The final
possibility would be that the proposition is true, but accepting
something as merely true already presupposes that we can use the
(epistemic) principle of non-contradiction of propositions, which in
turn is based on the (ontological) principle of non-contradiction of
entities.
We might be
skeptical about Hoffmann's desire to base epistemic principle of
non-contradiction on ontological principle of non-contradiction, but
it was quite common in his days. Hoffmann's proof is then a sort of
trilemma: either there is nothing to think about, when we discuss of
ontological contradictions, or then ontological contradictions just
are beyond our capacities to think – or then we must just accept
the principle of non-contradiction.
One might say that
this is a rather good proof that the principle of non-contradiction
is natural rule for us, since we cannot even imagine what it would
even be like, if world did not follow it, but that it does not really
justify that the principle also holds with real things. Hoffmann
accedes this point and asks us then to think about such a thing that
would both be and not be – since we cannot do it, we cannot even
say anything about it and it would thus lie completely outside the
realm of meaningful discussion, in which notion like truth can only
be applied.
Hoffmann's apparent
attempt has been to prove the validity of the principle of
non-contradiction, but what he has been capable of proving is more
like incapacity to speak of the truth of contradictions and the
existence of contradictory things, except by denying them – quite
good result in itself, since it makes evident that when discussing
truth, one can just assume that no contradictions exist. The only
remaining worry is that some other type of intelligence might find
contradictions quite acceptable and would be capable of speaking
about them, thus making it possible to connect the existence of
contradictions with the idea of truth. Hoffmann's only remark is that
while it is verbally possible to accept the existence of such
thinkers, from the viewpoint of out notion of truth such thinkers
would be speaking mere absurdities. In other words, such thinking
would be quite alien to our way of thinking and our notion of truth
and we would be quite justified to deny that their thinking has
anything to do with truth.
While we must thus
accept the principle of non-contradiction, as valid among all things
we have the ability to think of, in case of the two other highest
principles we must accept some restrictions. In a sense, we might be
able to use the very same method as we used in justifying the highest
principle. Suppose, for instance, that we must think about two
features, A and B, always as combined together, but that in actual
fact A and B would not be combined in some thing, but it would be A
without any B – say, while we must think that force is always
connected to some substance, there would be a force that would not be
connected to a substance. The problem in thinking about such a
possibility would be that we would have to think about a
contradiction – we would be naturally forced to think about the
necessary connection of force and substance, which makes us incapable
of even holding the notion that forces could exist without
substances. Again, this proof merely pushes the possibility of
things, which would cancel the validity of the second principle,
outside the realm of meaningful discussion. Furthermore, Hoffmann
holds, the second principle works only when the two properties are
both positive, that is, when we are referring to two ideas we must
always think together. If, on the other hand, the other idea is only
negative, that is, actually a mere lack of an idea, the necessity to
think of an idea together with a lack of another idea might just be a
result of our limited conceiving ability – Hoffmann is here
probably thinking of our incapacity to think of properties of God in
a positive manner.
The justification of
the third basic principle of proof follows a similar pattern as the
justification of the second principle. Hoffmann asks us to consider
two ideas we find repugnant to connect and then asks us to try and
think that the two would be actually connected – the result is that
there is actually no subject to talk about, since the two ideas
cancel one another. Just like with the other principles, the
justification removes all discussion of such combination of
incompatibles beyond field of meaningful discussion about truth. And
just like with second principle, Hoffmann notes that the third
principle can be used only in restricted manner – we might be
seduced by our inability to sense or perceive a connection of two
properties to think that they would be incombinable even in realms surpassing
mere senses. The restrictions on the two latter principles also make
metaphysics often into a mere probable discipline, Hoffmann concludes
– we cannot be completely certain whether some seemingly
incompatible combination of properties cannot truly be actualised.
Assuming Hoffmann's
justification of the three highest principles of inference have been
accepted as bridging the gulf between ideas and things, we can then
accept the rest of the principles justified through these three
principles. Often these sub-principles, such as Hoffmann's version of
the principle of sufficient reason, rely on some necessary
connection or incompatibility of ideas, which can then be accepted as
a proper pattern of inference in realm of things also through the use
of second or third main principle – thus, because we must always
think changes of a thing either as caused by external agents or as
happening through spontaneous action of the thing, in a meaningful discussion of truth this connection should be thought to hold also
between all things.
One can do little
with mere inference patterns or one needs some material propositions
as premisses of one's inferences. A simple set of these is provided
again by the highest principles – through the second and the third
principle we can accept as immediately true axioms all propositions combining things we necessarily connect and separating
what we necessarily separate. Yet, this is not enough, Hoffmann
admits, and we must also defend the general reliability of our
experience, and more precisely, of sensations, on which experience is
based.
Hoffmann's defence
of sensations is divided into three parts. Firstly, we must know that
we can distinguish sensations from other similar mental events, such
as imaginations. Hoffmann's justification for this seems overtly
simple: we can identify sensations as being produced by external
objects. In other words, in sensing the human consciousness is
passive, that is, it is incapable of saying what to sense – in
comparison, imaginations might be produced by free choice. Problem is
that we often still appear to be able to confuse sensations with
various other mental occurrences. Hoffmann himself admits as much and
delineates four cases where confusions might happen: when we are sick,
when we are dreaming, when our sensations are obscure and when we are
mixing implicit inferences with our sensations (in the last case
Hoffmann is referring to the famous case of a square tower that looks
round from a distance).
The first two cases
Hoffmann dismisses quickly just by saying that we are well able to
recognise sickness and dreams – since he is not explaining his
point, it is difficult to say whether he means that an external
observer could do it or whether he thinks there truly are some clear
marks, by which a sick or dreaming person could recognise one's
condition. The case of obscure sensations Hoffmann can clear up
pretty quickly by noticing that obscure sensations do not produce as
much confidence and can therefore be discarded because of the doubt
they produce.
The final case is
perhaps the most intriguing. Hoffmann notices that in affirming
something as round, we are actually saying that it has no angles. Yet, we
cannot straightaway sense lack of anything – we can merely not be
able to sense something. This lack of sensation might then be caused
by various things – there might not be anything to sense, but the
thing to be sensed might also be far away etc. When we then move from
a sensation of tower containing no angles to a proposition that the
tower has no angles, we are not just perceiving, but using this
perception as a ground for an unjustified inference – the
unreliability of the proposition is then no proof against the
reliability of sensations. Hoffmann also notes that all causal
propositions must be based on similar inferences, because we cannot
literally see one thing causing something else – an important
acknowledgement of a Humean statement.
Supposing then we
accept that Hoffmann has some evidence fo supposing that we do reasonably
well distinguish sensations from imaginations, we come to the second
question: is there actually any object behind a sensation? This is the
place where Hoffmann can criticize the two other leading theories of
body-soul-interaction: Leibnizian pre-established harmony and
occasionalism. Hoffmann attacks Leibniz' theory, because according to
it we could actually never distinguish sensations from imaginations,
since both are actually produced by the soul itself. Here Hoffmann
apparently doesn't notice that sensations might be so obscure that we
never really notice they have actually been produced by ourselves.
Yet, Hoffmann has a separate argument against that point: if the
difference between sensation and imagination is only that one is more obscure than the other, then this difference is only one of
degree and one could easily overcome it through careful
clarification. We are here approaching the Kantian idea that
sensation with its passivity is completely different in nature from
more active events of mental life and thus in need of a clear
demarcation from latter.
Occasionalism
doesn't pose as much a challenge to Hoffmann. Supposing God would
make us experience sensations – something he could well do,
Hoffmann admits – we would have to imagine that he wants to deceive
us into believing that things exist. Yet, this appears to contradict
God's good will, so there is no reason to believe that these things
would not exist.
The final question
concerning sensation is then whether sensation reveals accurately
what features an object has. Here Hoffmann has an easy answer. What
do we mean by saying that e.g. proposition ”grass is green” is
true? Surely it can only mean that when we observe certain object,
called grass, this object produces in us the sensation of green.
Generally, with such propositions based on immediate sensations,
truth means merely the accordance of the proposition with other
sensations (actual or possible). All we need to see, then, is that
sensations are reliably consistent in the sense that what we once
perceive as green is in similar conditions still green.
Now, all of the
arguments thus far have aimed at defending the possibility of
objective truth, that is, at showing that in an ideal case a person
following these rules of inference and having sensations could make
reliable conclusions. Problem is whether we can still prove the
possibility of subjective truth, that is, can we show that we are
actually in a position where e.g. we can reliably follow our
intuitions about connections between ideas. Hoffmann's answer is that
certainty lies in the inner sensation, in other words, in our
capacity to be aware of our own ideas as states of our mind. If we
have vivid enough sensations of our idea, we can be convinced that
our mental capacities are working fine and that we can rely on them
in constructing truth claims.
Problem of Cartesian
demon is still lurking. What if some powerful being would have made
us think that we are reliably perceiving something, even though we
are not? Hoffmann's peculiar answer is that according to his beliefs
such a being could only be God, and if God wants us to believe
something, then we know that belief is good for us, even if it is not
literally truth. The answer belies Hoffmann's pietistic background,
but also has an interesting pragmatist twist: if it works, why bother
fixing it.
This concludes the
theoretical part of Hoffmann's work. Yet, we are still only halfway
through his massive book, since we still have all of the practical
side to investigate. I shall begin with the question of using
experience correctly.