The word "rational" has more than one meaning. In common speech (and sometimes even in formal philosophy) the word often enough means a view or belief that is arrived at through a combination of logical reasoning and empirical evidence. However, the word when used in philosophy can often refer to a view or belief that is arrived at through logical reasoning alone. Thus, a "rationalist" is quite often a philosopher who ignores empirical evidence in favor of grounding their beliefs solely in logical reasoning.
In my view, rationalism poses a peculiar sort of danger that is derived from the fact a line of reasoning can be perfectly logical without being sound. That is, without being both logical and true at the same time.
For instance, consider this simple line of logical reasoning:
All men have horns.
Socrates is a man.
Therefore Socrates has horns.
The reasoning is perfectly logical but it is not sound. It is not grounded in truth. But that is a problem with all purely rational arguments. You can know if they are logical, but you cannot know if they are true (without resorting to empirical verification).
A popular example (in America) of a rationalist would be Ayn Rand. Rand almost never checked her views and theories against empirical evidence such as is found in the sciences or in the better histories. Hence, it seems likely she did not realize how far her views often deviated from anything strongly supported by empirical evidence. For instance, she divided people into two economic categories -- "makers and takers" -- and then assigned traits and attributes to each group that -- while logically derived from her definitions of the categories -- are simplistic to the point of absurdity when compared to empirical reality.
Rationalism has its uses, but without empirical verification, rationalism seems to rather quickly detour into the impractical and absurd. This is most likely the reason the sciences avoid rationalism in favor of a more balanced combination of logical reasoning and empirical evidence.
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In my view, rationalism poses a peculiar sort of danger that is derived from the fact a line of reasoning can be perfectly logical without being sound. That is, without being both logical and true at the same time.
For instance, consider this simple line of logical reasoning:
All men have horns.
Socrates is a man.
Therefore Socrates has horns.
The reasoning is perfectly logical but it is not sound. It is not grounded in truth. But that is a problem with all purely rational arguments. You can know if they are logical, but you cannot know if they are true (without resorting to empirical verification).
A popular example (in America) of a rationalist would be Ayn Rand. Rand almost never checked her views and theories against empirical evidence such as is found in the sciences or in the better histories. Hence, it seems likely she did not realize how far her views often deviated from anything strongly supported by empirical evidence. For instance, she divided people into two economic categories -- "makers and takers" -- and then assigned traits and attributes to each group that -- while logically derived from her definitions of the categories -- are simplistic to the point of absurdity when compared to empirical reality.
Rationalism has its uses, but without empirical verification, rationalism seems to rather quickly detour into the impractical and absurd. This is most likely the reason the sciences avoid rationalism in favor of a more balanced combination of logical reasoning and empirical evidence.
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