what makes the sensible default hypotheses non-task relativeness for edge recognition and contrast detection; or whatever broader category they lay in; when the rest of the procedure is task-relative? — fdrake
tasks (in the sense I think the phenomenologists meant it - 'doing the shopping', eating a sandwich'...) are modelled by areas of the brain several steps removed from the primary visual cortices. — Isaac
Let me suggest the way that Husserl and Merlea-Ponty would answer the question of whether there can be any such thing as a non task-relative sensation. But first, I’m wondering whether such a concept would fall under Sellars’s myth of the given.
Varela summarizes Goodman’s version of this:
“To be objective, the interpretationist points out, one would have to have some set of mind-independent objects to be designated by language or known by science. But can we find any such objects? Let us look at an extended example from the philosopher Nelson Goodman.
A point in space seems to be perfectly objective. But how are we to define the points of our everyday world? Points can be taken either as primitive elements, as intersecting lines, as certain triples of intersecting planes, or as certain classes of nesting volumes. These definitions are equally adequate, and yet they are incompatible: what a point is will vary with each form of description. For example, only in the first "version," to use Goodman's term, will a point be a primitive element. The objectivist, however, demands, "What are points really?" Goodman's response to this demand is worth quoting at length:
If the composition of points out of lines or of lines out of points is conventional rather than factual, points and lines themselves are no less so. ... If we say that our sample space is a combination of points, or of lines, or of regions, or a combination of combinations of points, or lines, or regions, or a combination of all these together, or is a single lump, then since none is identical with any of the rest, we are giving one among countless alternative conflicting descriptions of what the space is. And so we may regard the disagreements as not about the facts but as due to differences in the conventions-adopted in organizing or describing the space. What, then, is the neutral fact or thing described in these different terms? Neither the space (a) as an undivided whole nor (b) as a combination of everything involved in the several accounts; for (a) and (b) are but two among the various ways of organizing it. But what is it that is so organized? When we strip off as layers of convention all differences among ways of describing it, what is left? The onion is peeled down to its empty core.”
Now let me analyze a notion like ‘edge’ in the way that I think Husserl might. Imagine that we are a
creature recently emerged from the womb and just beginning to make perceptual sense of the environment via our various modalities of reception and action. Husserl begins with the assumption that we only experience a sensation as that sensation if it is meaningful to us, and its meaning is bound up with usefulness , that is, how perceiving something helps us to navigate our environment , to pick up and handle
objects, to recognize and pursue sources of food, shelter, danger, etc. It might seem obvious , even primitive, how the perception of edges are useful to us(there can be no object differentiated from a background without contrast). But is an edge
the same thing as a contrast? Let’s think about what is necessary in order to have an edge. First of all, an edge is not the same thing as a point in space. It implies a multiplicity of points or contrasts of some sort. Could we say the that it requires recognizing a surface? What is it that composes a surface? Our geometrical knowledge tells us that a surface has such and such characteristics, but isnt this a higher order abstraction? There can be no such thing as an abstract surface in nature any more than there can be a straight line. The point isn’t simply to question the primordiality in nature of perfect lines and surfaces but to question the very concept of a line or surface as a sensory given rather than a relative constructive hypothesis.
Surfaces are imperfect in shape, color , hue, brightness, texture, etc, notnbecause the are imperfect exemplars of the category ‘surface’ but because the very notion of surface as a unitary entity is an idealization subjectively constructed. And if this is true of a surface it is also true of its boundary. Often our visual sense cannot confirm a boundary that fades and disperses and gets lost and blended with changes in light, shadow, color , depth, etc. Sometimes only the recourse to movement and touch allow for a construction that leads to a notion of something like a boundary. And how many different meanings of boundary might there be, depending on how we are seeking to interact with it?
A ball has a boundary which appears as an edge visually but only when we attempt to interact with it do we discover the notion of sphericalness. There are boundaries between planes which pre-suppose
the notions of ‘in-front-of’ and behind. Recognition of such ‘edges’ protect us from falling off cliffs. Sometimes we don’t need to know what’s
behind or in front of. Instead we need to know what is above or below, to the left of or to the right of. Perhaps it is the boundary itself we are pursing in a directional fashion. And of course, the orientedness in space of a perceptual feature does not originarily take place in objective space but in the subjective space
of embodiment. My body is the zero point relative to which everything that I perceive is correlated and is orientated.
These orientation concepts are complex constructions , as we know from brain pathologies in which one loses the ability to process left from right. There are also brain injuries that cause neglect of one side of the field of vision or of the body. This is not due to damage to sensory reception but to a kind of apathy. (In Schizophrenia we often find a failure to demarcate where one’s body stops and the world begins. This bleeds over into the a failure to recognize boundaries of other objects. The issue here with edges isn’t one of sensory input but of significance, the relations between the object and my aims. If purposiveness becomes fragmented, the world and its contours fragments along with it. )
So are all these examples of goal-oriented tasks just different constructions based on a task-neutral sensory primitive called an ‘edge’? Husserl would say that none of them are, and that in fact there can be no such singular category like ‘edge’ that encompasses these varying contextual constructions. Each is telling the organism something original and invaluable to their present need to interact with an aspect of the world , about the way a new feature contrasts with the previous(aboveness, belowness, behind or in front of, sphericalness) in relation to one’s bodily position and in the context of how one is specifically intending to interact with an aspect of the world.
The question then becomes, from Husserl’s vantage, where do we get the idea that there are such subject-neutral things in nature called edges or points? His answer was that these are the product of an abstract idealization of the perceived world that was invented between the time of Aristotle and Galileo in the form of objective geometrical mathematization. This idealization was itself
designed to perform certain tasks, but has been taken as the foundation for the analysis of the perceived world, in the form of objective sensation primitives. The examples I gave above become imperfect variations derived from a gemotricized subject-independent space-time model of sensation.