Speaker
Description
Optical illusions were a feature of the architecture of Classical Greece and have continued to be an object of considerable interest to researchers in various fields. As far as visual perception is concerned, however, they became a selective battlefield for nativists and empiricists, particularly in the second half of the 19th century. My talk focuses on the last decade of that century, which saw the publication of three essays by Franz Brentano on optical illusions, such as the Müller-Lyer and Zöllner figures. Better known for his theoretical-philosophical model, he also developed an interest in rigorous experimental methodologies as part of his plans to formulate a philosophy on the solid basis of an empirical psychology devoid of the physical-materialistic schemes of positivism. It is in this light that Brentano’s interpretation of optical illusions and his refutation of Theodor Lipps and Joseph R.L. Delboeuf’s theories should be read. Indeed, by explaining the visual misunderstanding of the figures with the underestimation of obtuse angles and the overestimation of acute ones on the basis of his theory of judgment fully developed in Truth and Evidence, Brentano experimentally proved how “every perception counts as a judgment”, as he wrote. Accordingly, the analysis of optical illusions fell on the thesis that all judgments were existential, that the existential force of judgment was a mode or attitude, and that judgment was an “objectual” attitude. Following this perspective, Brentano went over the four categorical statements envisaged by Aristotelian logic that he studied through the lesson of Friedrich A. Trendelenburg, thus concluding that every judgment was reducible or “traceable back” (rückführbar) to an existential statement. All this means that an in-depth analysis of the interpretations of optical illusions must involve the analysis of the general research settings of their authors. This is particularly the case of Brentano, Lipps, and Delboeuf’s theoretical models.
