Common Sense

Here I take "common sense" in its broadest meaning. This includes everything from behavioral rules-of-thumb like "don't run with scissors" and "crime doesn't pay" to basic metaphysical principles like "something cannot both be and not be in the same way at the same time" and "everybody's got to be somewhere." What defines common sense in this broad sense is: Common sense is that which may reasonably be taken for granted until proven otherwise.  In other words, common sense is innocent until proven guilty.

Implicit in this definition is the possibility that common sense may be proven false. And, in this broad sense, it might be (at least in part.) For the broad definition includes basic metaphysical principles that cannot be proven false ("something cannot both be and not be in the same way at the same time") but also empirically contingent principles that can be and sometimes are proven false ("the Sun revolves around the Earth" was common sense for a long time).

If common sense might be wrong, why bother with it? Because it is necessary for embodied knowers like ourselves. Angels are eternal intellects who know immediately and directly and so have no need of common sense. Animals live through instinct and so have no need for it either. As rational animals, that is, animals that live through knowledge, we require knowledge to get on yet we are thrown into a world where we are born in ignorance. Our lives are a compromise born of the necessity to make our way in the world in at least partial ignorance.

Common sense is an expression of this compromise. We must take some view of the world to get on in it, and the world requires us to get on before answering all our questions.

There is a mindset that, seeing the apparent lack of foundation of common sense, finds it intolerable. Descartes was of this mindset, and spent his life attempting to construct a complete philosophy from indubitable first principles, so he would have no need of common sense. But whatever his purposes, Descartes remained an embodied knower, and so found it necessary to rely on common sense. This was true not just in his everyday life, where he took the common sense view that his basic perception of reality was correct; that his bed was really a bed, his house a house, and that he woke up in the same house every day. It was also true in his philosophy, where he was forced to adopt a "provisional morality" (i.e. common sense morality) while he spent time developing the "true morality" from first principles.

Contemporary scientism is also an expression of this mindset. The scientistic mind sees the knowledge produced methodically through the scientific method, sees that common sense has no foundation in method, and so dismisses common sense as without foundation entirely, and therefore not knowledge at all. But, like Descartes, the scientistic mind remains a rational animal nonetheless and so finds it necessary to repair to common sense. Again, not just in ordinary life, but in science as well, since science is nothing other than an activity of rational animals. The scientist takes for granted, through common sense, that the universe is consistent through time and space (F=ma both here and on the other side of the galaxy, and tomorrow as well as today) and that his senses more or less reflect reality as it is. He takes for granted that his telescopes, microscopes and galvonometers are in reality essentially what he thinks they are. But most significantly, the scientific method itself is verified only through common sense; when experimental scientists in New York and Paris independently obtain the same results, the fact that we think this strong evidence for the truth of the result is not itself the result of a scientific experiment. It is the result of our common sense belief concerning the consistency of the universe.

There is no escaping common sense, which simply means that there is no escaping our embodied existence (other than through death). But this doesn't mean we are doomed to ignorance, or that common sense must remain without foundation. Philosophy is the existential elaboration of common sense; rather than attempting a false escape from common sense ala Descartes or scientism, attempts that only obscure the foundation of our rationality in common sense, philosophy explores common sense as a means to distinguish firmly grounded knowledge from the merely conventional. The result is common sense uncommonly understood (to paraphrase Mortimer Adler).