Welcome to our fourth Ergo symposium, featuring Pendaran Roberts (University of Warwick), Keith Allen (University of York), and Kelly-Ann Schmidtke’s (University of Warwick) “Folk Intuitions about the Causal Theory of Perception” with commentaries by Eugen Fischer (University of East Anglia) and John Schwenkler (Florida State University). I’d like to thank each of the participants for all their hard work.

According to the ‘causal theory of perception’, it is a conceptual truth about perception that when you veridically perceive an object (e.g., see it), the object that you perceive causes your perception of it (Grice 1961; Strawson 1992; Lewis 1980). A traditional argument for the causal theory is that it successfully predicts and explains our patterns of intuitive judgments about when you do and do not qualify as seeing an actual object in front of you. For example, the causal theorist invites us to consider various hypothetical scenarios in which our perceptual experience intuitively matches the way the world is, but in which the causal processes underlying our experiences are somehow interfered with—e.g., through clever manipulation of your brain or environment. Intuitively, the causal theorist submits, you do not count as seeing what’s directly in front of you in these scenarios, even if your experience matches what the object is like. The best explanation for this, the causal theorist proposes, is that the causal condition required to apply the concept see is not satisfied in the scenario we have envisioned.

In their article, Roberts et al. empirically investigate whether the causal theory of perception embodies a conceptual truth about perception, as its proponents allege it does. To test this question, Roberts et al. performed an experiment in which philosophically untrained participants were presented with multiple vignettes describing hypothetical scenarios involving visual experience and actual material objects in the environment, and were asked to rate the degree to which they agree that, in the hypothetical scenario, they count as seeing the actual object. Significantly, among the vignettes describing causally deviant experiences, some described scenarios in which the source of causal interference is due to a blocker—i.e., an object that blocks the subject’s line of sight of an object, such as a mirror or a virtual reality head set—whereas other vignettes described scenarios in which something else interferes—e.g., ingestion of a hallucinogen or direct neural stimulation by neuroscientists. The main aim of Roberts et al.’s experiment was to determine whether participants’ intuitions about seeing are sensitive to causal deviance, as a causal theory of perception predicts, or more specifically to blockers.

Roberts et al. found that although participants tended to disagree strongly that they would be seeing a thing if their line of sight were blocked by something else, there was a lack of consensus among participants about whether having their experiences interfered with in some other way (e.g., by hallucinogens or direct brain stimulation) would prevent them from seeing what is actually there. More specifically, in cases of non-blocker causal deviance, while a large number of subjects strongly disagreed, a sizable number strongly agreed that they see the actual object. Roberts et al. interpret their finding as evidence that folk intuition about perception involves a no-blocker condition on veridical perception, rather than a more general causal condition. Consequently, they deny that the causal theory embodies a conceptual truth about perception. They conclude by arguing that their position is consistent with various views about conceptual truth, and defending their conclusion against alternative interpretations of their findings and potential objections to their experimental methodology.

You can find the target article, commentaries, and Roberts et al.’s response below.

Target article:

Roberts, Allen, & Schmidtke “Folk Intuitions about the Causal Theory of Perception”

Commentaries:

Eugen Fischer “Experimental Assessment of the Causal Theory of Perception”

John Schwenkler “How Do the Folk Think of Seeing?”

Authors’ Response:

Roberts, Allen, & Schmidtke “Folk Intuitions about the Causal Theory of Perception: Reply to Schwenkler and Fischer”

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