Since one has to strike while the iron is hot, here is my attempt to summarize the Critique of Pure Reason by Kant (1781) in a series of tweets.
(I am not a Kant scholar and so it's gonna be wrong but that's no problem since Kant scholars can just take what I did & improve) 1/??
(preamble: this is meant for my non-philosophy audience since most philosophers know all of this probably better than I do as I shamefully only read CPR when I was in my early thirties. Sorry. I read the excellent Guyer & Wood translation which combines A and B edition. 2/
Ok so Kant (1724 – 1804) lived most of his life in Königsberg, Prussia (now Kaliningrad in Russia).
He is known for the following key publications
Critique of Pure Reason (1781)
Critique of Practical Reason (1788)
Critique of Judgement (1790).
Now what does "critique" mean?
Preface (Axii) of Critique of pure reason: "I do not mean by this a critique of books and systems, but of the faculty of reason in general, in respect of all knowledge after which it may strive independently of all experience" 4/
Ah the Enlightenment--as much about the limits of reason than of its scope, take that Pinker (subtweet). The text is long, difficult, and really hard for beginners. I do not recommend CPR for non-philosophers. Instead, read Prolegomena, Kant's own light version of it. 5/
Kant was a great thinker, with huge influence on philosophy. He wrote on all the major topics in philosophy, including metaphysics, epistemology, ethics, aesthetics, law, politics.
But alas not a brilliant writer (sorry I'm probably getting cancelled by Kant twitter now) 6/
Kant went to university in Königsberg (the Albertina) at age 16, and left 6 years later. Was unable to secure a permanent academic position (a common problem then and now in the German-speaking world. First university post (private docent - Privatdozent) at age 31. Prof at 45 7/
He struggled with the problem: how do we combine knowledge obtained through senses with reason? (inaugural lecture as a professor). His answer to this problem was the Critique of Pure Reason (1781, 1787, CPR). 8/
The first edition is called the "A edition" (1781) the second "B edition" (1787). Kant scholars care a great deal about these and what's different between them but that's for when you really get into Kant. 9/
OK Preface. Kant lays the foundation for his critical theory. Prefaces introduce the problem of metaphysics. Why is metaphysics not making any progress? Our minds (reason) seem to ask questions all the time we can't answer e.g., whether you can know anything a prior 10/
In the B preface, Kant frames this problem in terms of Copernican revolution. Much like Copernicus shifted things by putting the Sun in the center, we need to realize that what we perceive depends on our cognitive capacities. Knowledge = not independent of our minds 11/
A preface says "Human reason has the peculiar fate ..that it is burdened with questions which it cannot dismiss, since they are given to it as problems by the nature of reason itself, but which it also cannot answer, since they transcend every capacity of human reason." 12/
But we can't help it, and so reason takes "refuge in principles that overstep all possible uses in experience … The battlefield of these endless controversies is called metaphysics” (A viii)
i.e., we try to make our reason do the impossible like answer whether God exists. 13/
And we don't make progress. We have been asking whether God exists for AGES and we're not closer to finding a solution. The solution to this problem: instead of trying grand solutions and invoking things outside experience, philosophy must start over and examine reason itself 14/
That way, we can discover what reason is capable of knowing. Kant is optimistic: an accurate analysis of reason will guarantee a correct and complete system of metaphysics. Ta-da! Hence the project, Critique of Pure Reason. 15/
Oh dear I was being a bit enthusiastic. I've just only summarized (a bit of) the A and B Preface. Maybe to be continued tomorrow. (That's gonna be a looong thread). At least now you know, non-philosophers, why it's called Critique of Pure Reason /16 (for now)
In the Introduction, Kant makes two important distinctions:
* a priori and a posteriori cognitions
* analytic and synthetic judgments
What are these, and why does it matter, you ask? /17
Let's start with analytic statements:
Their truth value is determined by the meanings of their terms,
e.g. All squares are 4-sided
All bachelors are unmarried
Bc bachelor means unmarried man, you don't need to go out into the world and check each bachelor. You know a priori /18
By contrast, a synthetic statement is one where the truth value is NOT determined by the meaning of its terms, e.g.
The earth revolves around the sun.
To know whether this is true it's not sufficient to reflect on the meaning of the words "earth" and "sun" you need experience/19
So then we have 4 possible options (table 1)
Kant thinks analytic a priori's easy (e.g., a triangle has 3 sides). As is a posteriori synthetic (e.g., snow is white).
But what about the remaining options? /20
Kant doesn't think there's such a thing as analytic a posteriori.
But what about synthetic a priori? Does it exist? Yes!
Kant believed math statements are synthetic a priori.
Even more controversially, he thought some statements in natural science are synthetic a priori /21
Now we get to the transcendental aesthetic, the part where Kant presents his first arguments that yes, synthetic a priori judgments do exist.
Btw we are here
Or this is an even better summary diagram by Andrew Stephenson /22 nebula.wsimg.com/f812ac8f2593c5…
Here Kant argues that time and space aren't objective mind-independent features of reality. Rather, our cognition adds those things to our perception. This explains how it is possible to have knowledge that is both synthetic and a priori /23
We learn about the world through our senses (what Kant terms "sensibility"). When when you learn about an object (in Kantian terms, when object is given to one), you get an intuition. These intuitions are the raw materials our minds work with. /24
“So objects are given to us by means of sensibility, and that’s our only way of getting intuitions; but objects are thought through the understanding, which gives us concepts.” (A19/B33) /25
Kant’s argument: based on perceptions of spatial-temporal objects, our representations of space and time originate in a priori or pure forms of sensibility. The science of all principles of a priori sensibility is what he calls the ‘transcendental aesthetic’ (A21/B35) /26
He formulates several arguments for why we should think that time and space
* are prior to and not derived from experience
* but ALSO are within us and actively contributed by us to sensation and experience rather than passively received from the outer world /27
Extremely summarizing these complicated arguments: The representation of space is of a singular, particular thing and, thus, is an intuition rather than a concept. Our representation of space is of an infinite and infinitely divisible whole
Analogous for time /28
Here Kant disagrees with Newton who sees time and space as existing as an absolute "stage" independent from observers (Einstein would later undermine that picture). Nope, says Kant time and space depend on/are generated by our cognition /29
He also argues that accepting that space = synthetic a priori allows us to see how geometry is possible.
Geometrical statements such as "the shortest distance between two points is a straight line" are synthetic (not in definition) but also necessarily true, so a priori /30
Aha but non-Euclidean geometry you might say triumphantly. Well, not a problem for Kant since he thinks geometry is a product of our cognition. He's not a realist about space anyway. All that is needed for this argument to work is that our intuitive geometry = euclidean /31