In this paper I will try to outline a Metaphysics of Perception that takes for granted one of the central thesis of the metaphysical doctrine called Indirect Realism. Firstly, I will introduce the central thesis of Indirect Realism and then a special version of the Causal Theory of Perception that modifies in some fundamental respect one of the most influential version of Causal Theory of Perception designed by William Child. To do this, I have asked myself who is involved in perceptual activity, if there is more than one kind of subject and more than one sense of perceiving that plays its part in what it is seemed a promising description of metaphysical aspects of perceptual activity.
This Metaphysic of Perception will be in line with the intuitions of who believes that perceiving is, in a way or another, an intentional activity with an intentional content; it will give a way to feature the phenomenal experience opened by the perceptual activity and it will put in its metaphysical place the causal relation between the physical objects perceived and the sensory organs by means of which we are allowed to see, smell and so on.
From a technical point of view, I will look not only for the necessary and sufficient conditions for a genuine perception, that it means trying to distinguish when a perception plays its own role from when it is given some experience indistinguishable from a perception but that is not a perception at all, but I will look for what I will feature as conditions for good perception, that is the metaphysical conditions of proper functioning of perceptive faculty. After doing that, at the end of the chapter, I will try to answer to the question of why the features of our perceptive experience are how they are.
In the second chapter, I will try to solve some main problem with various form of Causal Theory of Perception; problems that affect, in a way or another, the attempt to build a Metaphysic of Perception for which the causal relation in perception is a fundamental aspect. To do this I will give, en passant, a causal argument to reject one of the main philosophical positions that Indirect Realism is opposed to, the Naïve realism.
In the conclusions I will summarize the principal results obtained sketching this Metaphysic of Perception, its metaphysical structure and the four senses that I think can be metaphysically declined the verb to perceive.
A Threefold Metaphysics of Perception
In the history of analytical Metaphysic of Perception, two fundamental arguments were often discussed: The Argument from Illusion and The Argument From Hallucination. These arguments are pretended to prove that what we perceive are not material objects of the environment that surround us, that is what we usually think to perceive, but something different.
Who follows the conclusions of these arguments is forced to say that the properties of the objects that we commonly perceive are different from the properties that the objects really have. They often sustain that the perception of the objects of the environment that surround us is indirect and that exist a sort of “veil of perception” between us and the world around us.
To solve the problem, some influential philosopher has advanced a theory, The Causal Theory of Perception. Who embrace one form or another of this theory sustains that a causal nexus between the subject who perceives and the material objects of the environment that surrounds him it is necessary to perceive.
William Child in his work “Vision and Experience: the Causal Theory and The Disjunctive Conception”, searching for the necessary condition of “seeing”, writes: “If S sees O then: (a) There is a state of affairs reportable by a sentence of the form “It looks to S as if….”, and, (b) O is causally responsible for this state of affairs” (1992:298). This means that a subject S perceives an object O if S has an experience E and O is causally responsible that S has an experience E.
The problems, as far as I am concerned, with this way to settle the Causal Theory of Perception are of two kinds. The problem of the first kind is that not every perceptual experience E is a perception of an object O, in other words I have to know when an experience E can be considered the perception of an object O. The problem of the second kind is that is not clear who or what is the subject S of the first clause that has the experience E when he perceives the object O, who or what is the subject S of the second clause that is causally related with O, and if they are the same subject at all.
The subject S in the first clause, that can be called S’, is the conscious person that has an experience E like “the experience of is red home when he is going back from work”, whereas the subject S in the second clause, that can be called S’’, is the directly unperceived body with which the object perceived O is causally related in a physical relation that goes from the object O to the sensory organs of the subject S’’.
Moreover, there is another kind of subject, that can be called S’’’ or “experiential subject”, that is the subject inside the experience E. When the subject S’ has “ the experience of his red home when he is going back from work” he always experience the subject S’’’ has a part of his experience.
To return to the first problem, it is said that the causal theorist affirms that the first clause for an object O being perceived by a subject S’ is that S’ must have an experience E. Furthermore, it is said that not every perceptual experience E is a perception of an object O, too. To be an experience E of a subject S’ is needed that the subject S’ has an experience E and that there must be a phenomenal object X inner the experience E such that X stays in place of the material object O. Usually, to say that a phenomenal object X in the phenomenal experience stays in place of O it is said that the phenomenal object X matches the object O. The matching relation is considered to have a representational character such that every phenomenal object X and every experience E matches and therefore represents some object or environmental situation O.
David Lewis, talking about the matching relation, writes:
“That would almost follow from a requirement of match over a wide range of alternative scenes. But not quite. Most of our visual experience is rich in content; but some is poor in content and would match a wide range of alternative scenes equally well. Any pitch-dark scene would produce matching visual experience – what content there is would be entirely correct – but it would be the same in every case. Seeing is a capacity to discriminate, so this sort of match over a wide range of alternatives will not suffice. I conclude that the required pattern of counterfactual dependence may be specified as follows. There is a large class of alternative possible scenes before the subject’s eyes, and there are many mutually exclusive and jointly exhaustive subclasses thereof, such that (1) any scene in the large class would cause visual experience closely matching that scene, and (2) any two scenes in different subclasses would cause different visual experience. The requirement admits of degree in three ways. How large a class? How many subclasses? How close a match? The difference between veridical hallucination and genuine seeing is not sharp, on my analysis. It is fuzzy; when the requirement of suitable counterfactual dependence is met to some degree, but to a degree that falls far short of the standard set by normal seeing, we may expect borderline cases. And indeed it is easy to imagine cases of partial blindness, or of rudimentary prosthetic vision, in which the counterfactual dependence is unsatisfactory and it is therefore doubtful whether the subject may be said to see” (1980:246).
The point here is that not only there is not a unique experience that in principle matches an hypothetical object or situation O but that the matching relation is not necessary to have an authentic perceptual experience at all. Firstly, when a conscious person, a subject S’, has a phenomenal experience E there is nothing that this experience E says about the object or situation O or the subject S’’ that are causally responsible of E. The phenomenal experience E can be in principle and de facto totally different from the object or situation O, for his nature and for his properties, and we are not committed to affirms that E has to represent the object O, stay in place of it or matching it in some other ways.
What is requested for a phenomenal experience E of a subject S’ to be the perception of an object or situation O is that the unconscious bodily subject S’’ must successfully move inside the realm of the physical related object or situation O causally responsible of E when the conscious subject S’ moves inside the realm of the phenomenal experience E.
If my sensory organs are causally related with the objects of the environment around my body and my body enters in physical relation with these objects successfully when I consciously have a phenomenal experience and I move inside my phenomenal experience caused by these objects then I can say that I have a genuine perceptual experience.
What we perceive, ours phenomenal experiences, are in a way or another counterparts of the environment with which my unconscious body is sensory related. Between an environmental physical situation and its phenomenal counterpart there is not any particular and mandatory relation. If a subject S’’ moves successfully in its causally related physical environment when a conscious subject S’ moves in the causally corresponding phenomenal experience E then E is a good counterpart of the physical environment with which S’’ is causally related. For a poor and “strange” phenomenal experience of a non human conscious subject S’ the subject S’’, bodily considered as usual, can have a correspondent acceptable ability to live in his environment.
Now, Tim Crane in his “Is Perception a Propositional Attitude?” above the intentional theory of perception, says that a representation, in the way I have talk about them talking about perceptual relation, has not to have necessary truth condition but only accuracy condition (see Crane, 2009:457-461). While, it is said, there are no representational relation between perceptual phenomenal experiences counterparts and its related physical environment, there is a perceptual relation and representative too between the conscious subject S’ and the phenomenal experience E.
What it is noticeable is that it is the conscious subject S’’ that is intentionally related to phenomenal objects in quality of intentional content during perceptual activity and it is that the realm of the phenomenal experience is already available at the moment of the intentional perceptual representation.
If we talk about accuracy condition to represents intentionally the real or alternatively we take one or another of intentional theory of the kind object involving to show what we perceive, we have to consider that what is involved in object involving intentional theory of perception is coherently with which it is already said are nothing but the phenomenal objects of the phenomenal experience that fall under the focus of our attention or intentional observation .
It is said that what is necessary for a phenomenal experience E of a subject S’ to be the perception of an object or situation O is that the unconscious bodily subject S’’ must successfully move inside the realm of the physical related object or situation O causally responsible of E if the conscious subject S’ moves successfully inside the realm of the phenomenal experience E.
Inversely, for a phenomenal experience E of a subject S’ to be the perception of an object or situation O it is sufficient that if the unconscious bodily subject S’’ moves successfully inside the realm of the physical related object or situation O causally responsible of E, then the conscious subject S’ has to moves successfully inside the realm of the phenomenal experience E.
Now, for a subject S’, having a phenomenal experience E is equivalent to causally perceive a corresponding object or situation O if and only if, for the unconscious bodily subject S’’, moving successfully inside the realm of the physical related object or situation O causally responsible of E is equivalent to the moving successfully inside the realm of the phenomenal experience E of the conscious subject S’.
The conditions of causal perception that we have just seen are conditions that incidentally say that perception is not a way to know how reality is via some kind of representational relation with what is around us, but a way, with a phenomenal character, through which I can live adequately with all this comport in terms of fitness and, moreover, they say that the perception activity is a mental faculty too that has conditions under which it works or does not works.
The phenomenal experience that born from the perceptual activity is an interface between the subjects S’ and S’’, such that, to modification from the objects of the external, non-experiential world corresponds a change to the phenomenal experience of S’ and what he can do; while the changes of what S’ want to do in the realm of phenomenal experience modifies the way S’’ moves in the external world, once S’ has focused what he want.
Alva Noe says:
“In conclusion, perception is a causal concept, but it is also a concept of a kind of action. Perception depends on how things are, and it depends on what we do. When we perceive, we keep track not only of how things are, but of our changing relation to how things are. The upshot of this is that the problem with the causal theory is not that it can’t account for the right kind of causal relation, but that it neglects the perspectival content of perceptual experience. In perception, the world acts on us, and we act right back” (2003:99).
We have said that the phenomenal experience is an interface between a conscious person S’ and the external physical environment that is causally responsible of the phenomenal experience but we have not analyzed the interface relation. One main character of the interface relation is the feedback that the kind of subject S’’ has to the external environment through the action of the conscious subject S’ inner the phenomenal experience.
This kind of feedback is possible thanks to the cooperation of the three kind of subject S’, S’’, S’’’ operated by the human central nervous system. If the central nervous system worked on the phenomenal experiences of a subject S’ without translate this work in behavioral processes of the subject S’’ on his environment by the phenomenal relations between its phenomenal experiences and if there was not a continuous updating of the interface relation translating changes of relation between S’’ and the environment in changes of relation in the phenomenal experience and changes in the S’ will with changes in behavioral processes of S’’ through the attended results of S’ will in the phenomenal experience, then the human life should be practically impossible.
One may ask what is the gain to have three distinct kind of subject and a phenomenal experience respect to only a kind of subject S’’ who interact with its environment. The answer is that with a conscious person S’ and a phenomenal experience there is something to know and something to adapt to a will of a conscious person and not a simple physical stimulation to react to.
A second question is: Can a human living body do what it do with or without a S’ subject and a related phenomenal experience? No, because what with the human subject is related to in phenomenal experience is something with a proper character. When in my experience “ I move toward my red home” I have an experience that cannot be translated in the moving of a subject S’’ to a physical object that is “my home” because “my home” in this case could not be defined of some phenomenal type, color or mine, in any sense, anyway.
The way we have just characterized the perceptual activities permits us to distinguish between genuine perceptions, illusion and hallucination. Perception and illusion do not differ because the kind of phenomenal experiences caused by the respective environments are different but just because the phenomenal experience corresponding to illusion is intentionally judged to be in a way that differ from the way they really are.
In hallucinatory case opposite to genuine perception we have two phenomenal experiences too that differ because the genuine perception is a phenomenal experience caused by the physical environment while in the hallucinatory case the phenomenal experience is totally or partially not caused by anything at all.
Some problems with the Causal Theory of Perception
One famous problem with the Causal Theory of Perception is the Deviant Causal Chains and Veridical Hallucinations. The Deviant Causal Chains are causal relations that differ from the causal relation of a genuine perception with a particular phenomenal experience associated to thanks to the fact that the phenomenal experience remains in principle the same while the causal nexus is in a way or another interrupted or better, changed.
To solve the problem of Deviant Causal Chains is sufficient to reflect about the way we have characterized a good Causal Theory of Perception. There must be a causal relation between a subject of the kind S’’ and the physical environment; we need, so to speak, the causal organs of S’’ and if it is the case, his central nervous system. Now, if the relation of the physical environment is not with the sensory organs of S’’ but with something that can generate the same experience that has the subject of the kind S’ associated with S’’ in case of “normal” perception, the condition of good perception are equally satisfied.
More generally, if with a certain type of sensory device I can move successfully in my environment as S’’ thanks to my phenomenal experience as S’ caused by the physical objects around me and so on for the other condition of “good perception” that we have previously seen, then the Deviant Causal Chains are simply another way to obtain something like a “good perception”, they are nothing wrong nor something so deviant too.
Another problem with The Causal Theory of perception, a fundamental problem that historically can be traced back to Kant, has been recently exposed by another famous enough philosopher: H.P. Grice. Grice in his article named “The Causal Theory of Perception” writes:
“The Causal Theory of Perception (CTP) has for some time received comparatively little attention, mainly, I suspect, because it has generally assumed that the theory either asserts or involves as a consequence the proposition that material objects are unobservable, and that the unacceptability of this proposition is sufficient to dispose of the theory. […] But it may be argued that (in which is perhaps a somewhat special sense of consequence) it is an unwanted consequence of the CTP that material object are unobservable: for if we accept the contention of the CTP (1) that perceiving is to be analysed in causal terms, (2) that knowledge about perceived objects depends on causal inference, and (3) that the required causal inference will be unsound unless suitable general principle of correspondence can be provided, then we shall to admit that knowledge about perceived object is unobtainable. […] Now a model case of causal inference would be an inference from smoke to fire; the acceptability of such an inference involves the possibility of establishing a correlation between occurrences of smoke and occurrences of fire; 61 and this is only possible because this is a way of establishing the occurrence of a fire otherwise than by causal inference. But there is supposed to be no way of establishing the existence of particular material objects except by a causal inference from sense- impression; so such inferences cannot be rationally justified. The specification of principles of correspondence is of course an attempt to avert this consequence by rejecting the smoke-fire model (if this model is rejected, recourse may be had to an assimilation of material objects to such entities as electrons, the acceptability of which is regarded as being (roughly) a matter of their utility for the purposes of explanation and prediction; but this assimilation is repugnant for the reason that material objects, after having been first contrasted, as a paradigm case of uninvented entities, with the theoretical constructs or entia rationis of the scientist, are then trated as being themselves entia rationis)” (1961:121).
From a metaphysical point of view, the necessity of the causal nexus for perceptual activity is questioned by the forbidden inference from “smoke” to “fire”. We are always inner the phenomenal experience in quality of conscious subjects of S’ kind and because, at the end of the story, there is nothing like physical objects as O inner the phenomenal experience and nothing but phenomenal experience to what a conscious person appears to be linked to, then there is not something to correspond to “fire” in the inference “smoke to fire”.
It is nowadays a little bit strange to think to how we perceive without thinking to the causal nexus between the objects perceived and the sensory organs of the subject who perceive, without other specification, even if this link is not adequately understood. But from a metaphysical point of view if we distinguish the phenomenal experience from what is causal responsible of my phenomenal experience, then the existence of the causal nexus outside my phenomenal experience cannot be proved.
William Child, who puts in the spotlight a phenomenal version of The Causal Theory of Perception, considers what we have thought as phenomenal experience, the only and ultimate reality. Child writes:
“The second form of argument can be found in Strawson, Evans and ultimately traces back to Kant. It takes various form, but the central idea is this: the concept of perception is a concept of a way of finding out about an objective world; and in order to think of our perception as perception of an objective world; we must think of them as being causally explained by that world” (1992:298).
Now, if we think to sustain this kind of Naïve Causal Theory of Perception the problem is that, even if the theory challenges arguments as The Argument from Illusion and the Argument from Hallucination or similar, the scientific reports and explanations of perceptual activity that silently embrace a form of direct realism tell us that there is a short circuit between the thesis that we naïvely see material objects that surround us and the functioning of the causal relation between sensory organs and objects that tell us that it is not true that what we see are simply material objects. In case of vision the causal relation involves objects, light and the retina of who observes but to put shortly, the retina does not see anything at all and what arrives to areas of visions of central nervous system of the subject are signals that come from the neural activity after the retinal stimulation.
I cannot say to see objects nor I can say to see patterns of light. The objects and the patterns of light, reflected by objects, that arrive to the retina are two distinct things, and the patterns of light and the nervous signal processed by central nervous system after retinal stimulation, are two distinct things, too (for a review of perception for the neural sciences, see Kandel 2013:577-590).
But if this kind of The Causal Theory of Perception inspired by direct realism is forbidden and the inference “smoke to fire” for The Causal Theory of Perception of the type discussed at first is forbidden too, we can try to make consistent our Metaphysic of Perception appealing to a best explanation argument.
With William Child:
“For example, it may be that I am standing in front of a clock, and that it looks to me as if there is a clock of this type in front of me, but that my experience is being caused not by the clock but by a scientist directly stimulating my visual cortex. Or, Macbeth is hallucinating a dagger; a real dagger is then placed before him, so that the hallucination is now veridical; but the experience is not caused by the dagger (it would continue unchanged if the dagger were removed). In these and similar cases, our inclination is to say that the object is not seen. The causalist’s argument is that such cases highlight a causal requirement in our ordinary concept of seeing; the reason why the object is not seen is that it is not causally affecting the subject. The argument can be seen as an inference to the best explanation of why, in the problem cases, S is not seeing o. The best explanation, the causalist says, is that S is not seeing o because o is not causally affecting S” (1992:298).
The conditions to our Metaphysics of Perception based on a particular version of The Causal Theory of Perception are, it is true, necessary and sufficient because a perception is a good perception but only necessary and not jointly sufficient to say why the phenomenal inner experience is how it is.
Why we have a phenomenal inner experience of a kind X rather than a phenomenal experience of type Y? There are two answers to this question. From a metaphysical and physical point of view what has done that human phenomenal experience was of a type X rather than a type Y could have done in principle that human phenomenal experience was of type X rather than of type Y.
From a more abstract and biological point of view we have to say that perception faculty has a natural history and evolution and that it is this evolutionary history that has done ours phenomenal experiences how they are although they have could be in principle something different.
If we consider the condition of good perception discussed above jointly with the particular natural evolutionary history of the features of our phenomenal experience we should have the necessary and sufficient condition because our phenomenal experience is how it is.
Obviously that does not mean that everything about perception is explained. As David Pears puts the question:
“Lack of scientific knowledge about the brain may prevent us from giving all the details of the final stage of the causal line appropriate to seeing, but the theory of evolution comes to our aid at this point. The theory assures us that the final stage must be fairly restricted in its possible variations, like the other stages, which we can already specify. This does not mean that in the comparatively unknown stage the causation must follow a single line, because there may be back-up systems. But it does mean that there will be a low upper limit to the number of available alternatives” (1976:31).
We have seen that perception activity involves three related subjects. The subject S’ is the conscious person that has a phenomenal experience, the subject S’’’ is the phenomenal subject inner the phenomenal experience of S’ and the subject S’’ that is the physical subject causally relate to the physical environment causally responsible of the phenomenal experience of S’. We have seen that perceiving in this Metaphysics of Perception means at least four different things.
The first sense of perceive refers to this perceptual activity for what there are necessary and sufficient condition of genuine and good perception and a natural history for the feature that, de facto, the phenomenal experience has too. In a second sense “perceiving” means that the sensory organs of human body are, during perceptual activity, causally related with the objects that surround it. Third, perceiving means that a phenomenal experience formed by colours, shapes, smells, objects, faces etc. is given to me as public when I perceive in the first broader sense of perceiving and when the others do the same thing. In the fourth sense perceiving means that, me and equally the others, we are intentionally directed to what is inner ours phenomenal experience during the subjective and personal activities like observing, paying attention to something, judging and similar.
If a metaphysic who appeal to some form Naïve Realism is to put aside, a kind of metaphysics like that sketched in this paper is, as far as I am concerned, the best with what we have.
 Before moving on, I have to underline that the distinction between experience and physical environment it is not the distinction between something that has a physical nature and something that has a non- physical nature but the distinction between the material objects that enters in physical relation with ours sensory organs and the correspondent “phenomenal experience” although in scientific or philosophical terms they can be both considered part of the physical realm.
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