@013zen @Wayfarer
1) Voltage is not pressure; we are using one mode of thinking to facilitate another.
2) I've been mauling over recently if this is, perhaps, a re-envisioning of Maxwell's use of physical analogy in science, with the added concern of how to better adapt thought to those analogies in order to eliminate supposed "pseudo-problems".
3) .....................because all that is meant by "truth" is the correspondence, and whether or not there is such a correspondence, reality will tell us.
4) ..................there must be a certain conformity between nature and our thought. Experience teaches us that the requirement can be satisfied...............
5) But, then one can ask, in what sense can P, a proposition made up of words, correspond with reality made up of objects?
6) The map isn't a "true" representation of Boston but each map I look at has some of the correspondences with Boston and those correspondences might be "true" while others not. Reality is what tells you whether or not this is the case.
7) Is a volt a pressure? No, but certain similarities in one manner of thinking correspond to the other and can help to elucidate the other.
Taking the above into account, certain concepts may be helpful in working through the Tractatus.
What is the relationship between a model of the truth, a metaphorical truth, a simile expressing the truth or the literal truth
The Correspondence Theory means different things to different people
Correspondence means to have a close similarity, to match or agree almost entirely (Oxford Language Dictionary).
For the Direct Realist, as regards thought, if the Direct Realist sees a red postbox and thinks about this red postbox, their belief is that in the world exists a red postbox, and they are directly seeing it. Therefore, for the Direct Realist, there is no correspondence between what they see and think and what exists in the world, as what they see and think entirely agrees with what is in the world.
For the Indirect Realist, as regards thought, if the Indirect Realist sees a red postbox in the world and thinks about this red postbox, their belief is that in the world exists something that is not a red postbox but is causing them to see and think about a red postbox. Therefore, for the Indirect Realist, there is a correspondence between what they see and think and what exists in the world, as what they see and think only agrees with what is in the world.
As regards language, for both the Direct and Indirect Realist, there is a correspondence between the word and what exists in the world.
Therefore for Randall and Buchler, it is true that as regards thought, the Direct Realist believes they directly know reality and therefore don't need to compare their belief with the world, whereas for the Indirect Realist, as they believe they don't directly know reality, they therefore do need to compare their belief with the world.
What is a model of the truth
In thinking about why the sun rises in the east various models can be proposed. One model is that the Earth revolves around the sun. Another model is that the Sun was put into a chariot and everyday the God Helios would drive the chariot all along the sky causing the Sun to rise and set. It has been discovered that the model of the Earth revolving around the sun has proved more predictive that the model of the God Helio.
As any model can be improved, it is not that case that a particular model is wrong but that some models are more useful in particular contexts than others. For example, the model of the Earth revolving around the Sun may be more suitable in a science context, whereas the the model of the God Helios may be more suitable in a literary context.
It can also be seen that applying the wrong model in the wrong context may well result in unwanted philosophical problems which may well disappear if a more suitable model had been chosen. For example, on the one hand, using the God Helios model in a science context will clearly create philosophical problems that wouldn't have arisen if the Earth rotating around the Sun model was used. On the other hand, using the Earth rotating around the Sun model in the context of Greek mythology, in trying to understand the relationships between Helios and his parents Hyperion and Theia, will be clearly unhelpful
IE, no model is wrong in itself, but may be wrongly used. The purpose of a model is to be able to predict changes to the context within which it is being used.
Models, metaphors, similes and the literal truth in the example of seeing the colour "red"
If one sees the colour red, then one is thinking about the colour red.
1) For the Direct Realist, if one sees a red postbox then a red postbox exists in the world. The thought of a red postbox is neither a model, metaphor nor simile but is the literal truth.
2) a) For the Indirect Realist, if one sees a red postbox, the belief is that there is something in the world that caused the perception of such a red postbox. But what exactly that something is is unknowable, in the sense of Kant's noumena.
b) As regards models, the cause of what is seen can be modelled, such as a model of red postbox. Such a model exists in the mind and not the world, as the world is unknowable. The usefulness of the model is demonstrated by being able to predict changes in what is seen, not changes to what is in the world, but changes to what is seen.
c) However, it is a human characteristic to equate effect with cause. The cause of a bitter taste is a bitter drink, the cause of an acrid smell is acrid smoke, the cause of seeing the colour red is something that is red, the cause of heat on the skin is a hot object and the cause of a screeching noise is a screech. The effect is seeing a red postbox. The cause is categorised by the mind as a red postbox.
d) Therefore, what is the relation between what is seen (a red postbox) and what the mind has categorised as its cause (a red postbox). This relationship cannot be literal, as the effect is not the same as its cause. The relationship is not that of a simile, as the effect is not like the cause. The relationship must be that of a metaphor, because an identity has been assumed between two different things having a necessary property in common. Different in that one is an effect and the other is a cause, but sharing the necessary property that the mind has categorised the cause after the effect.
IE, for the Direct Realist seeing a red postbox is the literal truth and for the Indirect Realist seeing a red postbox is a metaphorical truth.
Models, metaphors, similes and the literal truth in the example of voltage and pressure
Is pressure a model, metaphor, simile or the literal truth in explaining voltage.
When one reads "Voltage is the pressure from an electrical circuit's power source that pushes charged electrons (current) through a conducting loop, enabling them to do work such as illuminating a light. In brief, voltage = pressure, and it is measured in volts" (
www.fluke.com) - in what sense does voltage = pressure.
In the Merriam Webster dictionary, the word "pressure" has several meanings, including "the action of a force against an opposing force" and "voltage" as "potential difference expressed in volts".
We can model voltage by thinking about the pressure of water causing water to run when a tap is opened, where the pressure of water in pipes becomes a model for the voltage determining current in a wire.
As a simile, the pressure of water in pipes is like the voltage determining current in a wire.
It may be that originally pressure only referred to water, but the meaning of words is not predetermined, and the meaning of words change with time, sometimes becoming more generalised. As the Merriam Webster dictionary notes, pressure may be taken as the interaction between two forces, and with a change in meaning, rather than saying voltage in wires is like pressure in water, we can now use the metaphor that voltage is pressure.
However, this then takes us to Donald Davidson and his article
What Metaphors Mean, where he argues that metaphors mean what their words literally mean and that there is no hidden metaphorical meaning. In effect, he is saying that what seem to be metaphors are in fact words being used literally. In the case of the seeming metaphorical expression "voltage is pressure", he is making the case that this means that voltage is literally pressure.
IE, even the expression "voltage is pressure" may be read not only as a model but also as a simile, metaphor and literally, all dependant upon one's point of view.