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Epistemological Strategies and Technological Conditions of Evidentiary Success

The rise of modern cell biology was deeply intertwined with the development of new experimental techniques and instruments that probed the inner workings of the cell. As the histologist Ramon y Cajal put it in somewhat purple prose, ‘every advance in staining technique is something like the acqusition of a new sense directed towards the unknown’ (quoted after Keller 2002, 215). Novel experimental techniques established themselves alongside more traditional methods such as optical microscopy; this required a continuous reassessment of how results from different methods could be made commensurable and could be reconciled.

Adopting a bird’s-eye view of the rapid growth of cell biology in the light of electron microscopy and cell fractionation, Bechtel writes of the two methods:

Both provided patterns of results that were determinate and repeatable. Each secured consilience of the results it generated with those obtained in other ways and, especially, with each other. (Bechtel 2006, 160)

Such consilience and mutual support across different methods, however, was not always initially apparent to their practitioners, many of whom brought divergent ‘interpretive modes’ (Rasmussen 1997, 124) and epistemological strategies to bear on the same results. Indeed, as Jane Maienschein has noted, it is often ‘epistemic convictions that dictate what will count as acceptable practice and how theory and practice should work together to yield legitimate scientific knowledge’ (Maienschein 2000, 123). As an example, consider Stuart Mudd, one of the contributors to cell membrane research (see fn. 12), who ‘worked to weaken the overall epistemological authority of light microscopy’ (Rasmussen 1997, 99); likewise, even among those who embraced the new techniques, there persisted methodological disputes concerning the uses to which the newly generated evidence—in particular, electron micrographs—should be put.

One such dispute, which has been given some attention by historians and philosophers of cell biology (Rasmussen 1997, 124-149; Bechtel 2006, 155-156), involved George Palade (at the Rockefeller Institute) and Fritiof Sjostrand (at Stockholm’s Karolinska Institute), both of whom were researching the mitochondrion. Whereas Palade’s use of electron micrographs ‘was primarily qualitative—to provide morphological perspective on the biochemical information generated [through other methods]’ (Bechtel 2006, 155), Sjostrand’s approach gave pride of place to the quantitative findings of electron microscopy, e.g. concerning the size of cellular components, without attempting to subordinate them to prior biochemical theories. Thus, whereas Palade refrained ‘from any effort to visualize [... the] membrane architectures’ of mitochondria, Sjostrand argued ‘that the thickness and appearance correspond to [...] the then-current “sandwich” theory of membrane biochemistry, from two layers of protein coating a lipid bilayer’ (Rasmussen 1997, 131/129)— that is, were similar in kind to the cell’s outer membrane structure.

While such methodological disputes are of intrinsic historical interest, they are also of broader philosophical significance, insofar as they raise ‘doubts about the degree of technological determinism that can be attributed to experimental systems’; as Rasmussen notes, in the particular case at hand ‘the two camps had practices that were so similar technically, yet they used the results so differently that they came to conflicting conclusions’ (1997, 125). Instead of technological determinism, we propose to speak of technological conditions of evidentiary success— that is, conditions of success (as discussed in Sect. 2.2) which are associated with specific technologies of experimentation. The mere availability of experimental techniques is never sufficient to bring about lasting theory change (in this case, concerning theories of membrane structure), but always requires conducive epistemological strategies among their practitioners. For example, Branton reports that his freeze-etching method—now credited with paving the way for the fluid-mosaic model—was met with scepticism, even from his former supervisor, Hans Moor.

From early on, it was clear ‘that freeze-etching frequently exposed vast expanses of a cell’s membranes to inspection in the electron microscope’,[1] yet whereas Moor ‘interpreted these expanses as the surface of the various membrane systems’ themselves, Branton came to realize that this interpretation ‘could not be reconciled with the known surface properties’ of membranes. Instead, ‘the fracture process used in freeze-etching was splitting biological membranes’, which led to a significant reinterpretation of the empirical findings. One of the main outcomes was the demonstration that, although ‘the membrane continuum was composed of a bilayer’, the reinterpreted findings ‘explicitly denied the notion of a biological membrane that was spatially uniform’. Without the advent of freeze-etching technology, the spatial non-uniformity in the samples might never have been observed. But, even more importantly, without the hard work of establishing shared standards of veridical interpretation for the new technique—which, as Branton’s example shows, oftens involves going against seemingly well-established prior theories and findings—the observed non-uniformities might have been easily brushed off as due to contamination or ‘noise’. Finally, the new technique brought into sharp focus previously unrecognized problems with the previous interpretation, which turned out to have been ‘based on a set of contradictory assumptions’; this suggests that certain technological conditions must indeed be met for empirical findings to reveal their true evidentiary significance.

Acknowledging that experimental techniques contribute to, but do not solely determine, conditions of evidentiary success also coheres well with the observation that what made some experiments in membrane research so influential were precisely those features (quality of the evidence, cohesion across time-resolved observations, determinate and repeatable patterns of results, etc.) that are also characteristic of evidentiary success in other domains. Consider Frye and Edidin’s demonstration of rapid mixing of proteins in heterokaryons. Widely credited with clinching the case for more ‘fluid’ accounts of the cell membrane, Frye and Edidin’s experiments displayed cohesion across different types of experimental techniques (use of antigen markers, inhibiting the cell’s metabolism), produced visually salient evidence through the use of immunofluorescence, and lent themselves to successful replication and modification.[2]

  • [1] All direct quotes from (Branton 1979: 9).
  • [2] See (Frye and Edidin 1970).
 
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