[...] philosophers have asked whether time in itself is bounded or unbounded; whether it is continuous or divisible; whether it flows; whether the passage of time is the same for everyone and everything everywhere; whether time is directional and if so whether its direction is a consequence of change, causation, or possibility; whether there can be time without change; whether it loops back on itself; and so on. How we happen to conceptualize time has been seen as irrelevant to such questions. It is assumed that philosophical inquiry can proceed without knowing or caring about the details of how human beings happen to conceptualize what is being studied. (pg.135)
[...] the metaphorical nature of our conceptual system, if unrecognized, can lead philosophers astray. Two things lead to such philosophical errors. First, a philosopher may fail to recognize conceptual metaphor and hence may see metaphorical sentences as literal and take them at face value. Once one takes a metaphor as being literal, the second error is to assume the correspondence theory of truth and therefore to regard the objective world as structured by the metaphor. [...] Augustine dramatized these errors in the eleventh chapter of his Confessions in his discussion of what constitutes a long time. Just when, he asks, is a time long? Is it long when it is present, or when it is past or future? [...] As a literal, metaphysical question about time, there is no answer, since only a short part of a process can occur at any present time. Augustine's answer is interesting. Past, present, and future, he says, do all "exist in some sort in the soul, but otherwhere I do not see them." A cognitive scientist who speaks about minds instead of souls might echo Augustine in contemporary terms, saying that the very idea of "lengths of time" is conceptual, and indeed metaphoric. Our very notion of a "long time" or "long process" is a product of our use of spatial metaphor.
Zeno's paradox of the arrow can also be seen as pointing out the mistake of taking a metaphor to be literal (though he didn't understand it as such). Suppose, Zeno argues, that time really is a sequence of points constituting a time line. Consider the flight of an arrow. At any point in time, the arrow is at some fixed location. At a later point, it is at another fixed location. The flight of the arrow would be like the sequence of still frames that make up a movie. Since the arrow is located at a single fixed place at every time, where, asks Zeno, is the motion? Time, Zeno argues, is not divided up into instants. In our terms, the idea that time is a linear sequence of points is metaphorical, a consequence of times seen as locations in the Moving Observer metaphor. The mistake, once again, is to take what is metaphorical as literal. [...] The appearance of paradox comes from attributing real existence to metaphorical point locations. Zeno's brilliance was to concoct an example that forced a contradiction upon us: literal motion and motion metaphorically conceptualized as a sequence of fixed locations at fixed points in time.
Such observations by Zeno and Augustine are not mere conundrums dreamed up in ancient and medieval philosophy, conundrums that are irrelevant today. They are early insights into the fact that our conceptual systems are not literal. They show that the most common concepts that we use every day and in terms of which we state our truths cannot he taken as literally fitting an objective reality. (pgs.156-158)
many of us would take a sentence like "Time is flowing by rapidly" to be true. Suppose you take this metaphor as being literal; that is, you assume that there really is a "flow" of time past us. This entails that the future is flowing toward us from somewhere and that it presently exists at the future "place." In short, it implies that the future, at least some of it, must exist at the present. [...] If you do not realize the metaphorical nature of the question, you might be led to ask, as some philosophers have, "If time flows, it has to flow at a rate relative to time. Mustn't there be some higher-order time relative to which time itself flows? " The question arises from taking the metaphor literally. To treat it as a deep metaphysical question would be silly. (pg.159)
Philosophers have observed that taking the theory of general relativity as literally true entails that the past, present, and future all exist "at once." That is, the theory seems to suggest determinism and the impossibility of free will or even random probabilistic events, as required by quantum mechanics. Of course, if one recognizes that general relativity uses our common metaphor for conceptualizing time metaphorically in terms of space, one need not reach such metaphysical conclusions. One can see general relativity as metaphorical. This does not make general relativity either false or fanciful or subjective, since its metaphors can still be apt. That is, they can entail non metaphorical predictions that can be verified or falsified. In general, to say that a science is metaphorical is not to belittle it. Because metaphors preserve inferences, and because those inferences can have non metaphorical consequences, one can often test whether or not a scientific metaphor is apt. Indeed, metaphor is what allows mathematical models to be linked to phenomena in the world and to be regarded as scientific theories. (pg.160)
What exactly was proved when Einstein's theory was "confirmed"? Einstein's theory claimed that a large body like the sun should create a significant space-time curvature in its immediate vicinity. If a light ray passed near the sun, it should follow a curved path. This was seen as providing for a test of the gravitational-pull theory versus the space-time-curvature theory. It was assumed that light had no mass; hence there should be no "pull" and the light should travel in a straight line by the sun. But if space-time was curved near the sun, such a light ray should travel along a curved path, mass or no mass. During an eclipse of the sun, the position was observed of a star that could not normally be seen next to the sun when it was shining. If space-time was curved, the light from the star should move in a curved path by the sun, and the star should appear shifted over a few degrees. The measurement was made during a 1919 eclipse, and Einstein's calculation of where the star should appear was verified. Einstein's theory was taken as confirmed-and interpreted literally: There is no force of gravity. What we've been calling that force is space-time curvature.
Einstein's theory need not have been interpreted literally. One could have said: Einstein has created a beautiful metaphorical system for doing calculations of the motion of light in a gravitational field. The metaphor of space as a temporal dimension allows him to use well understood mathematics to do his calculations. That is a magnificent metaphorical accomplishment. But that doesn't mean we have to understand that theory as characterizing the objectively true nature of the universe. (pg.228)
In superstring theory, all forces-gravitational, electromagnetic, and strong and weak nuclear forces-are conceptualized as curvatures in ten-dimensional space. What this does is allow the same mathematics, Riemannian geometry, to be used to calculate all of what we ordinarily call "forces." But of course, if one takes this theory literally, no forces at all exist as forces. What we used to conceptualize as forces are now all curvatures in ten-dimensional space. If we take superstring theory literally, no forces exist at all. And we live in a radically multidimensional universe, one with ten dimensions! Do we "really" live in a world with ten or more dimensions, many of them very small, with no forces but lots of curvatures in multidimensional space? Or is superstring theory an ingenious and productive technical metaphor that allows all calculations of force to be unified using the same mathematics - Riemannian geometry? These are not mutually exclusive alternatives. From the perspective of the everyday human conceptual system, superstring theory is metaphorical, as is general relativity, as is Newtonian mechanics. To take any of these theories literally is to say that force, and therefore causation, is nonexistent. But to take these scientific theories metaphorically is to allow for the "existence" of causes from our everyday perspective. (pg.230)
One important thing that cognitive science has revealed clearly is that we have multiple conceptual means for understanding and thinking about situations. What we take as "true" depends on how we conceptualize the situation at hand. From the perspective of our ordinary visual experience, the sun does rise; it does move up from behind the horizon. From the perspective of our scientific knowledge, it does not. Similarly, when we lift an object, we experience ourselves exerting a force to overcome a force pulling the object down. From the standpoint of our basic level experience, the force of gravity does exist, no matter what the general theory of relativity says. But if we are physicists concerned with calculating how light will move in the presence of a large mass, then it is advantageous to take the perspective of general relativity, in which there is no gravitational force. It is not that one is objectively true while the other is not. Both are human perspectives. One, the nonscientific one, is literal relative to human, body based conceptual systems. The other, the scientific one, is metaphorical relative to human, body-based conceptual systems. From the metaphorical scientific perspective of general relativity and superstring theory, gravitational force does not exist as an entity-instead it is space-time curvature. From the literal, nonscientific perspective, forces exist. Now, if we take one scientific theory or another as being literally true, and if we insist that there is only one truth and it is the best scientific truth we have, then, as Russell observed, force does not exist, and so neither does causation. If, however, we can allow scientific theories to be recognized for the metaphorical conceptual structures that they are for human beings, then we can allow multiple ways of conceptualizing the world, including both the scientific and nonscientific. Allowing for the multiple perspectives indicated by cognitive analyses allows us to maintain both scientific perspectives, in which causation doesn't exist, and our everyday perspective, in which it does. (pgs.231-2)
When someone asks, "Does causation exist?" that person usually wants to know whether there is a single unified phenomenon (which is called "causation") objectively existing in the mind independent world and operating according to a single logic. Furthermore, he or she assumes that there is a straightforward simple yes-or-no answer. As we have seen, the situation is more complex than that. But the presuppositions lying behind this apparently simple question are massively false. First, causation is a word in a human language and it designates a human category, a radial category of extraordinary complexity. In that complex radial category, there is no set of necessary and sufficient conditions that covers all the cases of causation. Therefore, causation as we conceptualize it is not a unified phenomenon. It does not simply designate an objectively existing category of phenomena, defined by necessary and sufficient conditions and operating with a single logic in the mind-independent world. Because the presuppositions lying behind the question are so far off base, the question has no simple straightforward answer. This eliminates a simpleminded realism that assumes that our language is simply a reflection of the mind-independent world, and hence that such questions are simple and straightforward. But eliminating simpleminded realism does not eliminate all forms of realism, and it does not require either idealism or total relativism. What remains is an embodied realism that recognizes that human language and thought are structured by, and bound to, embodied experience. In the case of physics, there is certainly a mind-independent world. But in order to conceptualize and describe it, we must use embodied human concepts and human language. Certain of those embodied human concepts, the basic-level ones, accord very well with middle-level physical experience and therefore have an epistemic priority for us. It is here that we feel comfortable saying that causation exists for ordinary cases of the direct application of physical force in our everyday lives. The central prototypical case in our basic-level experience gives us no problem in answering the question. He punched me in the arm. He caused me pain. Yes, causation exists. (pg.233)
George Lakoff & Mark Johnson - Philosophy in The Flesh (1999)