BURIDAN'S... IMPETUS

 

The clue to the title’s punctuation puzzle hides in our normal association of the notable French philosopher Jean Buridan (1295-1358) with “Buridan’s Ass”, whereas his actual originality lies elsewhere, particularly revealing itself in his discovery of the impetus. But, at any rate, he ought to be given an entry in this section for a number of such reasons, which we are going to explain further on in this entry.

By all accounts, Jean Buridan was a flamboyant, charismatic personality, which definitely differs from our stereotype of the medieval scholastic thinker. There is a peculiar, although superficial, connection between him and Nietzsche: They both came to philosophy from philology and the arts. In Buridan’s case, that may, perhaps, be one of the reasons why he seems to have avoided charges of heresy, normally brought against unorthodox thinkers in those times, and no one would contest the fact that Buridan was one. There was still another reason for his intellectual independence: Buridan deliberately never joined any religious order, and all his life remained a secular cleric.

Ironically, his Buridan’s Ass is not even original. It goes back to Aristotle’s De Caelo, where he pictures a man who is equally thirsty and hungry, placed equidistantly between drink and food, and thus being unable to make up his mind. Yet, at the end it was not Aristotle’s precedence, but Buridan’s affable colorfulness--- the hungry donkey perplexed between two stacks of hay--- that triumphed in establishing the Buridan’s Ass metaphor for all time.

There is a good reason why much of what Buridan wrote carries such strong ties to Aristotle, as most of his writings are direct commentaries on virtually all works of Aristotle. In this, he can be compared to the Talmudic and the later Jewish scholars who were writing commentaries on the Torah, and then on the Talmud itself. Such source dependence, however, did not preclude in any way their own originality and freshness of vision, and so was the case with Buridan, and his Aristotle.

Buridan’s most important work is Summulae de Dialectica, where he revisits Aristotle’s logic and comes to various original conclusions of his own. Summulae is a mammoth piece of work, and it reads with difficulty and produces a strong impression of tediousness. The following 20 Sophismata, which have become rather famous, are taken from it. They are exercises in formal logic. Some of them (like #7) are very familiar with a logical paradox contained in them. (Every proposition is false cannot be true because all propositions are false; but if it is false, then it has to be discarded for failing to tell us anything.) Others are sheer nonsense, and the only justification for uttering them is to launch a challenging chain of reasoning. This whole chain is known to logicians as “Buridan’s Bridge.”

It boils down to the following situation:

Socrates wants to cross a river, and comes to a bridge guarded by Plato, who says: “Socrates, if in the first proposition which you utter, you speak the truth, I will permit you to cross. But surely, if you speak falsely, I shall throw you into the water.” Socrates says: “You will throw me into the water.”

So, here now are Buridan’s Sophismata:

1.       Every proposition is affirmative, ergo no proposition is negative.

2.       No proposition is negative, ergo some proposition is negative.

3.       Every man is running, ergo a donkey is running.

4.       I say a man is a donkey.

5.       Whatever Socrates is hearing Plato is saying.

6.       It is true to say that a man is an animal.

7.       Every proposition is false.

8.       What Plato is saying is false.

9.       What Socrates is saying is true.

10.    There are the same number of true and false propositions.

11.    What I am saying is false.

12.    God exists and some conjunction is false.

13.    Socrates knows the proposition written on the wall to be doubtful to him.

14.    Either Socrates is sitting or the disjunction written on the wall is doubtful to Plato.

15.    Someone is doubting a proposition.

16.    You are going to answer in the negative.

17.    You are going to throw me into the water.

18.    Socrates wants to eat.

19.    Socrates is cursing Plato.

20.    Socrates wishes Plato harm.

The reader is welcome to go to the source and find out how Buridan is trying to build up a logical argument over this bizarre collection of seemingly pointless utterances…

Far more significant, although not completely new, was Buridan’s concept of Impetus. Aristotle’s theory of motion had no provision for inertia of moving objects. This aspect of his theory was challenged by Ioannes Philoponus (490-570), and later by Avicenna, but it was Jean Buridan who coined the term “impetus,” and described its meaning. Impetus was the motion-generating property of the moving body, which could not be extinguished, except by outside forces opposed to the movement, such as air resistance and gravity. He also argued that impetus increased with speed, thus envisaging the modern theory of momentum. Neither of his two predecessors, in criticizing Aristotle’s theory of motion, had gone this far, and therefore Buridan can be rightfully called original in his theory of impetus, and highly commended for it.

…Having said all that, I still somehow doubt that my wonderful reader, whenever the name of Buridan is going to be mentioned to him or to her again next time, will remember Buridan’s theory of impetus, or Buridan’s new tinkering with old logic, but it is far more likely that he or she will instantly and out of old habit revert to the more normal association of Jean Buridan: with Buridan’s Ass.