The hierarchy of knowledge
People will often sneer dismissively when one makes mention of fields of inquiry such as epistemology. Naturally, such idle endeavours must be hopelessly abstract and disconnected from the world of fact - perhaps a mere curiosity for those stranded in the Ivory Towers of academia. Not so. Epistemology profoundly affects every single aspect of philosophy it governs, and subsequently the sciences and political institutions of a given society. One can do no better than to consider the case of Ayer. He, like many other influential philosophers of the 20th century, was a logical positivist. Briefly, he posited that all knowledge is either factual - as in empirical - or pertaining to definitions (this is what constitutes the well-known analytic-synthetic dichotomy in philosophy.) For Ayer, the notion of a necessary truth that existed in the world as is would be fiction. The holes in logical positivism are many, and I will not here take the time to discredit a philosophy already mired in cobwebs. Allowing, for the purposes of this entry, the truth of logical positivism, where does this leave moral theories one might ask? What is a moral fact, if neither synthetic nor analytic (i.e. empirical or a matter of definitions)? But wait - moral fact? There's no such thing! At least, this is what Ayer would have us believe. As a consequence of his epistemological views, moral properties are mere emotive ejaculations. Why? Because clearly they are not empirical facts. Nor could they be analytic - for analytic truths are meaningless in the world solar systems, men, rivers, and the like. For Ayer, at best a statement such as "theft is wrong" is equivalent to "theft: boo!". Morality is thus rendered a matter of mere preference, of "anything goes", whether Ayer would admit it or not. As a matter of fact, it is interesting to note that in advancing his theory on morals, Ayer was hoping to dispose of a potential objection to his adherence to the analytic-synthetic dichotomy, and strengthen its plausibility. Personally, I view his attempt as entirely circular and wrong-headed. Logical positivism is dead. But it is a key example of how a theory of knowledge fundamentally affects every single aspect of how we view and interact with the world.
-Jon