You are at your yearly family dinner, and suddenly your Uncle JimBob remarks, “The economy is going into recession, and it’s all the Democrats’ fault! Their hatred of the free market makes it impossible for the economy to thrive!”
Now, apart from your uncle’s misrepresentation of the Democratic Party’s views, he is using a commonly misunderstood and misused word, a word in need of philosophical clarification: impossible. There are a variety of ways one could analyze this concept, and it is crucial that we, as rational thinkers, employ our terms with utmost clarity, precision, and accuracy. And in order to do this, we really need to know which usage of the word is being employed. So, let’s get into the definitions!
Possible: Some proposition, fact, or state of affairs is possible if it obtains in some possible world (that is, some way the world could have been without contradiction). It may or may not obtain in the actual world. Some proposition, fact, or state of affairs is possible (roughly) if it contains no internal contradictions or inconsistencies. However, there is a need to be much more precise with regards to possibility. It is useful to distinguish between logical and physical possibility.
Something is logically possible just in case it contains no internal contradictions. This includes if the physical laws in our current universe did not obtain.
Example: “Organisms with 8 limbs that breathe plasma and live on Jupiter” are logically possibly existent beings, and the propositions that “gravitational force is stronger than the strong nuclear force”, “I can walk through a wall” are likewise logically possible (despite being physically impossible).
Something is physically possible just in case it could obtain in our actual world with our actual physical laws.
Example: “It is physically possible to jump 2 feet in the air,” “It is physically possible for there to have been 5 planets in the solar system.”
Impossible: Some proposition, fact, or state of affairs is impossible if it cannot obtain. There are two broad types of impossibility.
Something is logically impossible just in case there are internal contradictions present in it. It exists (or is true) in no possible worlds.
Example: A square circle, 3 + 4 = 9
Something is physically impossible just in case it could not possibly obtain given the current physical laws that exist in our world.
Example: A human being the size of an atom is physically impossible.
Necessary: Some fact, proposition, or state of affairs is necessary just in case it cannot not exist; it cannot fail to exist; it must exist; it could not have been otherwise; it exists in all possible worlds; it is not possible for it to fail to obtain.
Example: 2 + 2 = 4, a Euclidian triangle has interior angles summing to 180 degrees, all bachelors are unmarried, all red roses are colored, humans are animals, water is dihidrogen monoxide.
Contingent: Some fact, proposition, or state of affairs is contingent just in it can be otherwise or could have been otherwise; it could have not obtained; it does not have to exist; it is not necessary for it not to obtain.
Example: It is contingently true that it is raining outside: it could be otherwise.
In the next post, I will consider the a priori/a posteriori and the analytic/synthetic distinction.