What is the role of mental images in the perception of absence?

Question

In the book “Metaphysics, a very short introduction” by Stephen Mumford, near the end of Chapter 9 titled “Is nothing something?”, I read the following puzzling lines:

“Jean-Paul Sartre discussed the case of entering a restaurant and seeing that Pierre is absent. How can anyone do that? Absences can’t be perceived directly, for how would the absence of Pierre look any different from the absence of Jacques or the absence of a hippopotamus? Absent things look like nothing so, in that respect, they are indistinguishable. It seems problematic to say that the absence of Pierre is inferred from what is seen because, just like the hippopotamus case, there is nothing you see that entails he’s not there. It’s just that he’s not. The judgement might be of a primitive, non-deductive kind, then. We just have an ability to judge that something is not, which is denying that it is. You deny that Pierre is in the room because you’ve had a good look around and, try as you might, you couldn’t find him.”

I would like to focus on the phrase “there is nothing you see that entails he’s not there”.

I think that there is indeed something. It is the mental image of Pierre (not Jacques!) being in the restaurant. That image is compared with the actually observed one, and the resulting difference is seen as an absence. So there is nothing problematic in saying that the absence of Pierre is inferred from what is seen.

It seems that we constantly form mental images of opposites. When I make the assertion “Pierre is in the restaurant”, what I first and foremost do is pose the problem of the relation between Pierre, the restaurant and “being inside”. Pierre may be or may be not there, but in either case, I first get hold of the two opposing images and only then I proceed to make my judgment, in a clearly non-primitive, deductive way.

My question is: is there a way to refute my objection to the above quoted paragraph?

Answer 1

Calling it a mental image is an oversimplification of the logical quagmire of negation. This logic of the absence of knowledge has been extensively debated for millennia by Hindu and Buddhist logicians and philosophers. Vicente Fatone writes in his book The Philosophy of Nagarjuna on page 118-20:

Nevertheless, whether one adopts the primary attitude which does hesitate to attribute reality to non-being, or affirms instead that non-being escapes the possibilities of the judgement and the latter refers only to the present absence of being, the problem remains unsolved, for the question still remains: "How is absence recognized?", or "How is non-presence recognized?" The most simple and least satisfactory solution remits the problem to inference, forgetting the negative judgement (that which serves as reason) which is what one is trying to explain. The most radical solution remits the problem to perception of the non-existent. Nagarjuna goes further than the later philosophers. In the face of difficulty of negative judgements (of a knowledge which would have to refer to a reality, like any knowledge, and which cannot refer to it, for if it referred to a reality it must do so by affirming, and not by negating it) he opts for the condemnation of the negative judgement itself. He is bound to this judgement if he proceeds from the principle according to which affirmation or negation--judgement--can be referred only to that which is, for it is not possible to affirm or to negate that which is not. Hos method consists of in reducing the judgement itself, be it affirmative or negative, to absurdity although this reduction to absurdity itself appears absurd. In the method itself is affirmed the activity of judgement, which one claims to negate. The essence of the dharmas--the adversity would say--cannot be negated. If it be negated and if the judgement whereby it is negated is true, the the dharmas have essence.

The essence of the dharmas exists, since it can be refuted. The refutation of the essence implies the recognition of the essence of the dharmas in general and the recognition, in particular, of the essence of the judgement called judgement.

Here we find ourselves in the attitude, so familiar to us in the West, according to which nothingness can neither be affirmed nor thought of nor can it contain something more than the concept of something (the latter and its negation). Strictly speaking, we cannot refer to nothingness either affirmatively or negatively. In the face of nothingness the quality of the copula is dissolved. Every judgement is either affirmative or negative, and affirmation, as well as negation, is incompatible with nothingness. Nothingness cannot be affirmed, nothingness cannot be negated. Indian thought has laid emphasis on the second aspect, for the negative judgement has in it an importance greater than what obtains in the Western tradition. Nagarjuna concedes that what is not cannot be negated. Affirmation and negation only make sense insofar as they refer to that which is. The Buddhist texts abound in the formulation, in a variety of forms, of this principle: that which is not is neither affirmed nor is it negated. The affirmation--as well as the negation--of that does nor imply contradiction.`

Answer 2

I have not read this book nor familiar with the author.

But I believe there are two relevant concepts that support your claim and do not refute it. The concepts are information channels and triangulation.

James Ladyman and Tim Maudlin (two unrelated philosophers) both claim our senses and perception are information channels. An important feature of an information channel is that absence of singal is still information transmitted.

Maudlin uses a different example, that of a dog barking or not barking to inform you if a person is outside.

Bas van Fraassen brought up the idea of triangulation of the senses. Me not hearing the dog causes my mental image to expect not to see a person outside.

Since our senses capture something real or structural about the world, we can use these information channels and triangulation among the different senses to derive well informed conclusions.

Answer 3

This is somewhat futile. We would need to read both Mumford's book as well as the entire fragment of Sartre's book discussed by Mumford.

This being said, who is Stephen Mumford?

Stephen Dean Mumford (born 31 July 1965) is a British philosopher, who is currently Head of Department and Professor of Metaphysics in the Department of Philosophy at Durham University.[1] Mumford is best known for his work in metaphysics on dispositions and laws, but has also made contributions in the philosophy of sport. -- https://en.wikipedia.org/wiki/Stephen_Mumford

He wrote several books and at least twenty articles in various philosophical journals. So it seems Mumford is typical of today's metaphysicians.

Repeat of Mumford's considerations:

Jean-Paul Sartre discussed the case of entering a restaurant and seeing that Pierre is absent. How can anyone do that? Absences can’t be perceived directly, for how would the absence of Pierre look any different from the absence of Jacques or the absence of a hippopotamus? Absent things look like nothing so, in that respect, they are indistinguishable. It seems problematic to say that the absence of Pierre is inferred from what is seen because, just like the hippopotamus case, there is nothing you see that entails he’s not there. It’s just that he’s not. The judgement might be of a primitive, non-deductive kind, then. We just have an ability to judge that something is not, which is denying that it is. You deny that Pierre is in the room because you’ve had a good look around and, try as you might, you couldn’t find him.

Absences can’t be perceived directly

Sartre himself didn't talk about seeing or perceiving an absence. This is typical of the analytical technique used in metaphysics whereby you essentialise the absence of something as if it was itself something. It is trivial to realise that someone you know is not in a room and this does not require the perception of this person's absence.

for how would the absence of Pierre look any different from the absence of Jacques or the absence of a hippopotamus?

Indeed, so we cannot perceive the absence of person, but this is still not what Sartre said he was doing.

It seems problematic to say that the absence of Pierre is inferred from what is seen because, just like the hippopotamus case, there is nothing you see that entails he’s not there. It’s just that he’s not.

there is nothing you see that entails he’s not there. Mumford does not understand logic. We all routinely infer from what we see around us the absence of particular things. Looking now around me, I can infer the absence of Donald Trump. Is my inference correct? I don't know but I still inevitably infer that Trump is not here near me. I could not infer that God is not here, and I could not infer that the current king of France is not here, but I could infer that Joe Biden is also not here, as well as a myriad of other particular things. We all do that and there is no difficulty.

The judgement might be of a primitive, non-deductive kind, then.

Mumford really does not understand logic. Whenever you infer something from something else, it is a deduction. There is no other sort of inference.

We just have an ability to judge that something is not, which is denying that it is.

This is moving into typical metaphysical mumbo-jumbo. To realise that someone you know is absent from a place is to realise that it is not the case that this person is present. To equate this with the statement that "something is not" is fallacious. The absence of something is not a case of something which is not, unless you want to say that the presence of Pierre is not, which would be fallacious because we don't infer from the absence of something at a particular place that this thing is absent at all places and therefore does not exist.

You deny that Pierre is in the room because you’ve had a good look around and, try as you might, you couldn’t find him.

Exactly. Oh, he does understand the situation, then!