9
‘In addition to natural interpretations, Galileo also
changes sensations that seem to endanger Copernicus. He admits that
there are such sensations, he praises Copernicus for having disregarded them,
he claims to have removed them with the help of his telescope. However he
offers no theoretical reasons why the telescope should be expected to
give a true picture of the sky.’
Feyerabend says –
‘For while it might be admitted that Copernicus simply acted
on faith, it may also be said that Galileo found himself in an entirely
different position. Galileo, after all, invented a new dynamics. And he
invented the telescope. The new dynamics, one might point out, removes the
inconsistency between the motion of the earth and the ‘conditions affecting
ourselves and those in the air above us’. And the telescope removes the ‘even
more glaring’ clash between the changes in the apparent brightness of Mars and
Venus as predicted on the basis of the Copernican scheme and as seen with the
naked eye. This incidentally is Galileo’s own view. He admits that ‘were it not
for the existence of a superior and better sense than natural and common sense
to join forces with reason’ he would have been ‘much more recalcitrant towards
the Copernican system’. The ‘superior and better sense’ is of course, the
telescope, and one is inclined to remark that the apparent counterinductive
procedure was as a matter of fact induction (or conjecture plus
refutation plus new conjecture) but one based on a better
experience, containing not only better natural interpretations but also a
better sensory core than was available to Galileo’s Aristotelian predecessors.
This matter must now be examined in more detail.’
‘The telescope is a superior and better sense’ that gives
new and more reliable evidence for judging astronomical matters. How is this
hypothesis examined, and what arguments are presented in its favour?’
in the Sidereus Nuncius Galileo writes that he
‘succeeded (in building the telescope) through a deep study of the theory
of refraction’
Feyerabend says this suggests that Galileo had theoretical
reasons for preferring the results of telescopic observations – to observations
with the naked eye
but according to Feyerabend the particular reason Galileo
gives – his insight into the theory of refraction – is not correct and not
sufficient
Feyerabend here points out that Galileo in a letter to
Guiliano Medici in 1610 more than half a year after the publication of the Sidereus
Nuncius – asks for a copy of Kepler’s Optics of 1604 saying he had not been
able to obtain it in Italy
and that Jean Tarde who in 1614 asked Galileo about the
construction of telescopes of pre-assigned magnification – says that Galileo
regarded the matter as difficult and that he found Kepler’s Optics so obscure
‘that perhaps its own author had not understood it’
also in a letter to Liceti two years before his death
Galileo says the nature of light is still in darkness
Feyerabend concludes Galileo’s knowledge of optics was
inferior to that of Kepler’s
ok
first off Galileo does not claim to have a superior
knowledge of optics to that of Kepler
he says Kepler’s book is virtually unreadable –
you cannot assume from this claim that Galileo concludes
anything at all about Kepler’s knowledge
further it doesn’t tell us anything about Galileo’s
knowledge
the fact that he may have regarded the nature of light as
still in darkness – again does not tell us anything in particular about
Galileo’s mastery or not of the subject
it is fair enough to assume that in making such a statement
Galileo knew something of what he was talking about
in my opinion it suggests he has looked at the various
theories and found them all wanting – or something along these lines
also ‘a deep study of the theory of refraction’ – means just
that – a deep study
one can make a deep study of subject and still be unclear or
unsure of its principles
we don’t know if this was the case with Galileo
but it is clear that deep study does not necessarily result
in one being confident about one’s knowledge
so what can we make of his claim that he succeeded in
building the telescope through a deep study of the theory of refraction?
I am inclined to accept Galileo at his word
a deep – albeit inconclusive study – may well result in the
production of an instrument
let’s say that in Galileo’s mind the construction of the
telescope was the a result of his study of refraction
and we can ask – what other ‘explanation’ did he have –
could he have had?
let us assume for argument’s sake that Galileo is mistaken
here – that even though he explains the making of the telescope in terms of his
study – in fact there were other factors involved which he did not recognize
such as i.e. luck or inspiration
we can say here Galileo’s view of what he accomplished is
only one view –
other accounts are possible
in this case we really don’t have enough information as to
what did or did not go on
perhaps if you got right down to it Galileo might have to
admit he did not know how he made the telescope with any certainty
this is not to question the instrument or its making – just
the epistemology surrounding it
in any case Feyerabend clearly thinks that if you can show
Galileo was deficient in his knowledge of the theory of refraction – then he
did not really have any theoretical reasons for preferring the observations of
the telescope over those of the naked eye
my point would be – even if Galileo was not confident in his
knowledge of the theory of refraction –
this in itself is not relevant for why one would regard the
telescope’s observations as preferable to those of the naked eye
a theory of refraction will explain how the telescope works
– it will also explain how the eye works
the theory of refraction will not give you reason for
preferring one over the other
it is actually irrelevant to this question
Galileo says of the telescope that it removes the ‘even more
glaring’ clash between the changes in the apparent brightness of Mars and Venus
as predicted on the basis of the Copernican scheme and as seen with the naked
eye
so the clash between the Copernican theory and the naked eye
is removed by the use of telescope
it seems clear to me that the theoretical reason Galileo
gives for preferring the telescope as an instrument over the naked eye (as an
instrument) is just that its results can be seen to support of the Copernican
view
and here we have a genuine theoretical reason
Feyerabend’s argument about theoretical preference here
depends on a confusion between different kinds of theory – a theory of
refraction – on the one hand – and a cosmological theory on the other hand
the theory of refraction will not settle the issue of the
preference of instruments – the naked eye or the telescope –
it seems that for Galileo – the issue is settled by the
support that the telescope’s results give to the Copernican cosmology
whether you agree with him or not here – you have to admit –
it is a genuine reason in support of one theory against another
Feyerabend goes on to quote Professor E Hoppe –
‘Galileo’s assertion that having heard of the Dutch
telescope he reconstructed the apparatus by mathematical calculation must of
course be understood with a grain of salt; for in his writings we do not find
any calculations and the report by letter, which he gives of his first effort
says that no better lenses had been available; six days later we find him on
the way to Venice with a better piece to hand it as a gift to the Doge Leonardi
Donati. This does not look like calculation; it rather looks like trial and
error. The Calculation may well have been of a different kind, and here he
succeeded, for on 25 August 1609
his salary was increased by a factor of three.’
the only real argument here is that there were no
calculations found in his writings
this does not mean no calculations were made
and even if you accept the so called alternative – it is
hard to see how a process of trial and error – in the making of a telescope –
would not involve calculation
Feyerabend goes on to say –
‘‘it was experience and not mathematics that led
Galileo to a serene faith in the reliability of his device’. [Geymonat] This
second hypothesis on the origin of the telescope is also supported by Galileo’s
testimony, in which he writes that he had tested the telescope ‘a hundred times
on a hundred thousand stars and other objects.’’ [Letter to Cariosco 1616]
the reality is that ‘experience’ is the problematic – what
is to count as genuine experience?
the observations of the naked eye or the observations
obtained via the telescope?
experience actually will not arbitrate the matter – what
decides the issue here?
clearly Galileo’s preference for the Copernican system
the argument of the telescope is really that it makes the
naked eye argument irrelevant
the observations of the naked eye can now be seen as a
limited case of telescopic vision
that is to say the naked eye has not been refuted – rather
it has been incorporated into a larger vision
our interest becomes then not what is seen with the naked
eye – but rather what can be seen when the naked eye is extended
the argument of the telescope is that it enables us to have
greater vision
this is primarily an instrumentalist argument
it is the instrument – not its theory – that enables us to
see experience in a new light
in the appendix 2 of this chapter Feyerabend says –
‘It is different with the psychological problems
raised by the telescopic observations. These problems were seen by Pecham and
others (such as Roger Bacon) and they still remain (moon illusion). At the time
of Galileo they were tremendous, and they account for the strange reports (some
of which were discussed in my text). These problems are comparable to the
problems of somebody who, having never seen a lens before, looks for the first
time into a very bad microscope. Not knowing what to expect (after all,
one doesn’t meet man size fleas on the sidewalk), he is unable to separate the
properties of the ‘object’ from the ‘illusions’ created by the instrument
(distortions; coloured fringes; discolouring; etc.) and he cannot make sense of
the objects themselves. On the surface of the earth – with buildings, ships,
etc. – the telescope of course will work well; these are familiar things and
our knowledge of them eliminates most distortions just as the first
observers soon noticed, and said. Thus it is true
that the telescope causes illusions both in the sky and in the terrestrial
cases (p. 20), but only the heavenly illusions were a real problem, for the
reasons just stated.’
outside of an observational context – any observation – of
the naked eye or of another instrument such as the telescope will be without
known reference
which is to say the observation will not be identifiable –
it will not be describable – it is an unknown
what is to count as real and what is to count as illusion is
always a matter of context –
i.e. relative to the use of a particular instrument in a
particular context – distortions etc. will be regarded as real –
that is they are real effects of such a use of the
instrument in that context
on the other hand relative to a broader epistemological
context that involves complex scientific theory and complex philosophical
theory – these effects can be categorized as non-central and hence
illusory
it all depends finally – not on what is there – but
rather what you are looking for
that is it depends on the conceptions – the proposals
– you bring to the observation
with the original use of the telescope in the celestial
context – the issue is of course – just the establishment of the context
–
factors involved in this process will be e.g. previous
observational preconceptions – the state of the critical discussion – and the
goals of the current endeavour etc.
may I suggest that at the beginning – looking through the
telescope into the heavens – the only clear vision was the unknown
Feyerabend began this chapter with –
‘However, he offers no theoretical reasons why the telescope
should be expected to give a true picture of the sky’.
Feyerabend does not show that Galileo held the view that the
‘telescope should be expected to give a true picture of the sky’
we can safely assume Galileo believed that the telescope
provides a different picture of the sky
we just don’t know if this picture was for Galileo – the
‘true’ picture
it is at least conceivable that Galileo did not think a
‘true picture’ – in the sense of an end to the matter – was achievable
which is to say he may just have had an open mind on the
nature of the heavens
we do know that he favoured the Copernican view and that he
thought the observations from the telescope supported that view
having said this it nevertheless strikes me that Galileo
regarded the instrumental advantage of the telescope to be obvious to anyone
with their eyes open
in the end however –
what we have from Galileo here – is a proposal – nothing more –
a proposal that is open to question – open to doubt – and is
in every respect – uncertain
