The technological argument

A common realist retort to the anthropocentric distinction between observables and unobservables is that the boundary shifts with the progress in the avail-able instruments of observations. The point was implied by Maxwell’s series of gradually observable objects: if observability/unobservability is a contin-uum, then the view that observability is detection by unaided senses involves an untenable limitation. The same objection is raised explicitly against van Fraassen by Paul Churchland (1985). Churchland’s argument invokes the pos-sibility of genetic mutations to the effect of drastically extending the human sensory abilities. (As will be seen in 4.3, the argument has also been raised against Fodor’s distinction between observation and inference.)

We have already pointed out that van Fraassen’s epistemology demands a concept of observability free from contextual dependencies. For that reason, he

cannot just equate observability with current detectability, since the bound-aries of the latter extend as the technology advances. He de-contextualizes observability by equating it to detectability by the unaided senses, but the toll for this move is that he has to accept a slew of implausible consequences.

Maxwell mentioned the possibility of human mutants able to detect ultravi-olet radiation with the naked eye (Maxwell 1962: 11). In a fictional mood, Churchland (1985) imagines human mutants and extraterrestrial beings en-dowed with electron-microscope eyes. These beings ascribe high degrees of credence to sentences about which the ‘normal’ constructive empiricist is ag-nostic. The question that should now be raised is whether these rational creatures can be excluded from the scientific community on the basis of van Fraassen’s observability principle. As a matter of fact, van Fraassen foresaw this objection:

It will be objected ... that ... what the antirealist decides to believe about the world depends in part on what he believes to be his, or rather the epistemic community’s, accessible range of evidence. At present, we count the human race as the epistemic community to which we belong;

but this race may mutate, or that community may be increased by adding other animals (terrestrial or extra-terrestrial) through relevant ideological or moral decisions (“to count them as persons”). Hence the antirealist would, on my proposal, have to accept conditions of the form

If the epistemic community changes in fashion Y, then my beliefs about the world will change in fashionZ.

(van Fraassen 1980: 18)

Concerning the concrete form of the function relating eventual epistemic changes to changes in the world, van Fraassen defers to “relevant ideological or moral decisions”. However, what ideological and moral decision-makers can offer are conventional, hence ultimately arbitrary decisions. This is precisely what Maxwell and Churchland criticize.

After all, as Kukla (1998: 134) indicates, the requirement that we agree on what is observable does not entail that all of us have the same sensory capacities. Blind or deaf scientists are not – or should not be – less than full members of their scientific communities. What is required in the event that scientist Acan observe some phenomenon perceptually prohibited to scientist B is that B be willing tocredit A’s observational reports.

At this point, the scenario splits into two parts. On the one hand, if there is a significant overlap of their sensory capacities, A and B can agree on the conditions of mutual scientific credit. On the other hand, if no sensory overlap is in place, things are more complicated. It seems to me that in this latter

case there is no guarantee that A and B can ever become members of the same scientific community. What would be required, as Kukla suggests, is the existence of a manifold of beings whose perceptual abilities overlap so as to constitute a continuum at whose ends are situatedAandB, respectively. Each sentient being in this continuum would have a sensory spectrum that overlaps with the one of his ‘perceptual neighbor’. Imaginably, perceptual epistemic credit could be the outcome of complex transmission of epistemic credit along this chain. Yet, unlike Kukla, I do not see any warrant that such a ‘sensorial chain’ could ever be constructed. I contend that Kukla relies too heavily on a far-fetched piece of science fiction, the image of an intergalactic cosmopolis populated by beings harmoniously complementing each other’s abilities. Cer-tainly, this is not a logical impossibility. However, we don’t know whether this is physically possible. We cannot be sure that for any two rational beings, A and B, no matter how large the gap between their sensorial endowments, epistemic agreement can be reached. It may actually be the case that the physiologies ofA andB are so different that there can be no effective contact between their sciences.

But doesn’t our latter point speak in favor of van Fraassen’s distinction? It appears as if different sensorial endowments engender different sciences, which is certainly absurd. It is one thing to claim thatanyposited theoretical entity may be detected by a sentient – existent or created by genetic engineering – being; and it is a different one to admit, as van Fraassen himself does, that the limits of observability can be shifted. We don’t know whether it is physically possible to extend the limits of sensorial detectability so as to reach any unobservable entity in the universe. But, comparatively, it is a modest step to admit that those limits will shift from the current state, as we often have a fairly clear idea about the direction of that shift. This is all that is needed to place van Fraassen in a difficult position. For if we know now that the limits of observability can shift as to make possible tomorrow the detection by unaided senses of what we now think of as an unobservable entity, then we shouldnow have a definite, nonzero degree of belief in that entity.

In any event, van Fraassen admits openly the eventuality of enlarging the scientific community:

Significant encounters with dolphins, extraterrestrials, or the products if our own genetic engineering may lead us to widen the epistemic commu-nity. (van Fraassen 1985: 256)

However, in order to mitigate the problem of the arbitrariness of the decision as to how large the scientific community actually is, van Fraassen cannot al-low a lot of tolerance about the borders of the latter. He must stick to his anthropocentrism, no matter how implausible its consequences. And indeed

he does, as he produces a rather species-chauvinist answer to the question of

‘what do we do with all these intelligent beings which candidate to adhere to our cognitive community?’ They – dolphins, extraterrestrials, etc. – he says,

are, according to our science, reliable indicators of whatever the usual combination of human with electron microscope reliably indicates. What we believe, given this consequence drawn from science and evidence, is determined by the opinion we have about science’s empirical adequacy – and the extension of “observable” is, ex hypothesi, unchanged. (van Fraassen 1985: 256–7)

The extension of the scientific community thus envisaged consists not in ad-mitting new members with equal rights, but only in equipping the extant ones with new instruments.

Since the interest here is not in a discussion of the ethical implications of van Fraassen’s epistemology, it has to be conceded that, whatever the short-comings of chauvinism, it is not an incoherent epistemic position. Accordingly, an observable/unobservable distinction drawn in terms of a species’ sensorial limitations can survive the technological argument.