Outline:

• The apparent "subjectivity" of time
  David Hume and the problem of causality (supplement with "Notes" on Hume)
  Immanuel Kant: Turning Subjectivity into Objectivity (supplement with handouts, notes from Jones, on Kant's epistemology and its consequences for
  • the Newtonian/Cartesian epistemology, including
    the dualistic logic of Descartes, especially as expressed in
    a) the insistence on either truth (as 100% certain, final, absolute, etc.) or falsehood (including the "merely" probable), and
    b) the sharp dichotomy between "objectivity" and "subjectivity" --
• Relativity Theory

Kant - primarily through a philosophical device known as "analogical predication" re-introduces a "both/and" or complementary logic into modern thought, expressed as

• a) the concept of knowledge as a process in which the subject/knower and the object/known are interwoven, as the various aspects of the human knower (frameworks of time and space, the categories of understanding [including causality], the ideas of reason) work to actively shape, filter, and organize the scatter of sense-data (grounded in an external reality) into a coherent experience (= knowledge of the phenomenal world - the world as it thus appears to us)
  issuing in a complementary relation between subject and object, as expressed in the catchphrase "Concepts [of understanding/mind] without percepts [of sense-data] are empty: Percepts without concepts are blind." Concepts as form require the content of sense experience.
  
  b) the (Aristotelian) acknowledgement of a plurality of truths (e.g., the practical and the theoretical, the scientific and the metaphysical, etc.) and degrees of knowledge.
  

But at the cost of moving from the realist belief that natural science provides us with an account of "the way things really are" (in Kant's language, the way things are in themselves) to a more instrumentalist account of knowledge and natural science.

Kant: given that science "works" only for the phenomenal world - i.e., the world of our experience as constructed through our own frameworks and categories - science is forever cut off from knowledge of "the way things really are," thus restoring in the modern period the instrumentalist character of natural science as emphasized in its earlier history.)

The reductionist/positivist tendency in Descartes and Newton:

if natural science succeeds in providing us with a full and complete account of "the way things really are" - then

a) only scientific knowledge is legitimate knowledge, and hence

b) all other knowledge claims (including those of religion and philosophy) must either be reduced to strictly scientific - and thus deterministic, quantified, mathematical - accounts
or be rejected entirely (e.g., traditional religious and philosophical beliefs in free will, non-material entities such as values, souls, divine beings, etc., insofar as these are excluded from the Newtonian/Cartesian universe).

Kant: natural science is legitimate - Kant is able to save natural science from Hume's empiricist critique, but at the cost of making natural science, as centrally focused on causal relationships among the objects of sense, possible only as "causality" is a category the human subject contributes to the knowledge process. (Hume was right about "causality" as something that has no direct empirical experience to give it meaning.)
But this means: science is limited to the world of our experience, the phenomenal world we create as we construct/shape/filter sense-data into a coherent experience (e.g., by imposing the category of causality on that sense-data).
But this means: natural science does not provide the full and complete account of "the way things really are." Rather, natural science provide an account of the things of our experience - where "experience" is precisely limited to what we construct out of sense-data using our own categories and frameworks.
It is thus possible that things exist/act "outside" the phenomenal domain of our experience - things which, if they can be "known" at all, can only be known in ways different from the way we know things in the phenomenal domain via natural science.
This means that a plurality of knowledge is possible - one which may include rather than exclude other kinds of claims (e.g., the claims of philosophy and religion regarding free will, etc.)

Summary:

Kant saves natural science from Hume's critique (i.e., from the effort to make science strictly "empiricist")
by introducing an "idealist" epistemology (one which acknowledges the role of the human forms of knowing in constructing our experience/knowledge of the phenomenal world).

But Kant's epistemology thereby limits natural science - and thereby also saves "faith" (i.e., the belief in human beings as free agents, etc.)

Kant's "Copernican Revolution" is in some ways far more fundamental than the revolution attributed to Copernicus.

Copernicus, Galileo, Kepler et al. force a shift from the "naive" view that presumes the earth stands still while the rest of the universe circles round us - and demonstrate that in order to explain how things appear to us (first of all, retrograde motion of the planets), we must understand the motion of both the observer and the observed.
Similarly, Kant's "Copernican Revolution" shifts us from

• the "naive" (and especially Anglo-American/Empiricist) view that presumes that the way things appear to us is the way things really are
  to the "Copernican" view that the activity of the observer contributes to how the observed appears to us.
  

But this is not simply an observation about the physical motion of the planet on which we stand: it is a more fundamental account of how humans know - whatever it is they seek to know. Not just astronomers seeking to understand the motion of the planets - but all human beings, as human beings are "Copernicans," i.e., knowers whose own activity (imposing the frameworks of time/space, the categories of understanding [causality], etc.) contribute to the entire cosmos of their "knowledge"/experience.

This epistemological revolution, moreover, prepares the way for still more dramatic shifts in our Cartesian/Newtonian "classical" understanding of the world. As Pine puts it:

• Kant's philosophy ...prepared the way to think about the possibility that there are many "real" events, other worlds, happening all the time right in front of us, so to speak, even though we are incapable of directly experiencing them. It would soon be commonplace for scientists to believe that there are many realities beyond the perceptual window allowed by Newtonian conceptual filters. Kant was right about our normal perceptual window. It is Newtonian. Every observation scientists make, whether it be in an Earth laboratory or of deep space, will be framed wtihin a normal three-dimesnional window. Although Kant himself believed this would never be possible, it would soon be commonplace to believe that there could beindirect methods of deucing other realities, that observations made in our normal mode could indicate or point to a world totally different from what we normally observe....
  Ironically, in his attempt to establish Newtonianism as a priori, Kant prepared the way for us to think the unthinkable: that we could conceptualize, understand, and even have knowledge of new unimaginable realities, that our common notion of three-dimensional space, our normal experience of the unidirectional flow of time, and our thoughts about causality could be but a human point of view. (197f.)

This will happen in two key ways: Einstein and Relativity, and Quantum Mechanics

Einstein and Relativity.

Special relativity involves the empirical effort to "test" time, to provide "time" with an empirical basis as tied to the speed of light as a universal constant. The results of Einstein's empiricism - like the results of Hume's empiricism - is the destruction of fundamental elements of the Cartesian/Newtonian conception of the universe: far from being "absolute" frameworks, the "sensorium of God," -

a) space and time are relative to the framework of the observer - i.e., utterly dependent upon the motion of the observer.

Einstein thus provides a physical analogue to Kant's epistemological understanding of the role of the human knower in constructing the framework of time/space which organizes our experience. This is part of the meaning of Schrödinger's comment: "Einstein has not ... given the lie to Kant's deep thoughts on the idealization of space and time; he has, on the contrary, made a large step towards its accomplishment." [quoted in Pine, 198]

More broadly:

• ...in relativity theory, the observer is intimately involved inscientific measurement, and what is measured can be different, depending on one's reference frame....In the destruction of the notions of absolute space and time, Einstein showed than an honest empiricism must involve the observe, that to some extent what is real does depend on us. [Pine, 207]

The quote from Paul Davies is also helpful:

• The essential element injected into physics by the theory of relativity is subjectivity. Fundamental things like duration, length, past, present and future can no longer be regarded as a dependable framework within which to live our lives. Instead, they are flexible, elastic qualities, and their values depend on precisely who is measuring them. In this sense the observer is beginning to play a rather central role in the nature of theworld. It has become meaningless to ask whose clock is "really" right, or what is the "real" distance between two places, or what is happening on Mars "now." There is no "real" duration, extension or common present.
  [Other Worlds: A Portrait of Nature in Rebellion - Space, Superspace and the Quantum Universe (New York: Simon and Schuster, 1980, p. 42, in Pine, 207]

b) a plurality of different frameworks/experiences of the same event(s) is possible - i.e., different observers, moving at different speeds, will experience the same event in starkly different ways (e.g., the lighting strikes as seen by two different observers [Pine, 200f.], and, more generally, time as "clocked" by light bouncing between two mirrors, as seen by two different observers [class example].)

It is also important to note that this "relativity" does not mean that Einstein gives up on the possibility of science achieving a realist understanding of how nature behaves. (Rather to the contrary: we will see that Einstein's realism is the fundamental ground for his resistance to still another overturning of the Cartesian/Newtonian framework - namely, quantum mechanics.)

In addition, in his General Relativity theory, Einstein does for the Newtonian conception of the universe what the moderns and Newton did for the Medieval/Aristotelian account of the universe - with a result that is as hard for us to "believe" as the Copernican hypothesis was for its critics. Briefly, "gravity" - the centerpiece of Newtonian science and the paradigm of the relationship between things whose universal effects can be mathematically formulated - is eliminated as an unnecessary "explanatory entity." Rather, what we ordinarily refer to as the "effects" of "gravity" are "really" the result of distortions in space/time as a continuum caused by bodies - warps which affect the motion of bodies, including planets and galaxies.

Finally:

• Einstein showed that what was masquerading as a removal of humankind and subjectivism from science [i.e., Newtonianism and the assumption of an absolute framework of time and space] was actually a projection of a subjective human point of view, which is close enough to the truth at a certain level to enable us to fail to recognize it as a human point of view. (Pine, 209)

Next: Pine, ch. 8: Quantum Mechanics and "The Copenhagen Interpretation"

Specific features of quantum mechanics directly challenge - if not suspend or overturn - the fundamental assumptions of Newtonian mechanics