As far as rationality is concerned, there are two uses — discovery and verification. There is a well-known mathematical claim called P not equal to NP. It means that you can verify in polynomial time (finite time) but you need non-polynomial time (exponential time) for discovery. I have given the example of password discovery and verification. Verification of passwords requires a very small time, but the discovery of passwords (by hacking) takes a very long time. So, rationality has a role in verification, but the scientific method uses it for discovery. That is where the issue is.
The is another issue with rationalism, which is that all reason ends in axioms. You cannot test axioms by reason. You cannot test axioms by empiricism either, because many axioms will equally suffice for the same explanation. You choose axioms, based on what you consider “good postulates”. But, what is good in this context is not good in another context. So, questions of “good” don’t take us far. Then we defer to what is the right choice — for me. Truth doesn’t stand alone; it needs the support of good and right, and the three combine to provide knowledge. So, the fault in rationalism (or empiricism) is that they try to consider just truth.
Then again, even this ‘truth’ is contextual (because axioms are good for me, right for me). And it must always remain contextual because all meanings involve oppositions. You cannot define top without defining bottom, left without right, etc. So, you cannot have a logical universal truth in the sense of something that avoids contradictions, if you are dealing in meanings. All truth is local truth, which we also call ‘relative’ truth, rather than ‘absolute’ truth.
The Absolute Truth is that which is self-contradictory. It is all the contradictory propositions as its aspects. In Vedic philosophy, this Absolute Truth is also known as ‘God’. One aspect of God is gentle, another aspect is ferocious; one aspect is honest and another aspect is deceitful; one aspect is the biggest and another aspect is the smallest. To understand this Absolute Truth, one has to go beyond conventional logic and understand how opposites emanate from Him.
Then, as a matter of routine, the idea that the world moves due to reason is false in Vedic philosophy. The world moves due to contradictions or conflicts. If you write a book, you have these problems to deal with; if you don’t write a book, you have another set of problems to deal with. So, you are conflicted between these alternatives, and that conflict creates choice. The soul makes the choice, but the choice is forced by contradictions. So, the cause of change is not consistency but contradiction. In science, we assume that reason moves the world through cause and effect (because the effect rationally follows the cause). But if you examine human thinking, it is always caught between cost-benefit analysis alternatives. If the best thing was also the easiest thing, then consciousness would never need to make choices. The choices are forced because there are tradeoffs and we cause change by selecting on specific tradeoff.
In summary, there are many levels at which ‘rationalism’ is wrong:
1. It helps in verification, but not in the discovery
2. The quest for truth is inadequate without right and good
3. All self-consistent truth is contextual; the universal truth is self-contradictory
4. Matter creates contradictions, choice resolves these contradictions
Each of these themes has been discussed at length in various posts and books if you are interested to delve deeper into the topics. I haven’t yet put them together in one place, but you can do it if you like. Rationalism believes that (a) it can discover the truth, (b) that the truth is universal, (c) that the truth stands without right and good, and (d) the world is rational. Each of these claims can be disputed, and I have disputed them. The above is a summary.