6 DECEMBER 1969, Page 15

Matters of fact

J. 0. URMSON

Ifetaphysies and Common Sense A. J. Ayer Macmillan 58s) This is a collection of fifteen essays and ad- dresses written over the past fifteen years. All have been or will be published elsewhere, but only the largest libraries are likely 'to possess more than a fraction of them already.

A philosopher so eminent as Professor Ayer is in demand to deliver formal lectures before axgust bodies on ceremonial oc- casions. Some of these addresses originated in this way and are what one would con- sequently expect. Being by Ayer, they are lucid, urbane, sane and interesting, but they do not present the results of sustained original thought on a problem that has grip- ped his attention.

Other essays are of more substantial ,iri- terest. All save subscribers to Syrithe.ve will be glad to find `Has Austin Refuted the Sense- Datum Theory?' reprinted here. Ayer cer- tainly shows that not all the barbed shafts of Sense and Sensibilia strike the theory to the heart, and all who were impressed by that book should • read this essay. The review of Malcolm's Dreaming is devastating. The essay on chance is lucid on a topic that usually generates much confusion.

But the most interesting feature of the volume is the set of essays which raise on- tological issues, notably `What must there Be?', 'Metaphysics and Common Sense', and 'G. E. Moore on Propositions and Facts.' Thinking within a conceptual scheme, Ayer holds, good sense requires us to go along with it; within 'our current conceptual system it is simply true that there exists a prime number greater than three and less than seven. But may we not raise what may be called external questions? May we not ask whether the concept of number is necessary to a satisfactory conceptual system? Ayer treats this issue sensitively, though it is hard to see how one can raise an issue at all Without being within a conceptual system already. If, for example, we, with Ayer, re- ject propositions on the ground that to posit them gives us only a misleading appearance of an analysis of meaning, must we not do so gainst the background of our other seman- tic concepts?

Moreover, is it clear that when Ayer re- ts propositions in this way the concept of roPosition is the same as when we affirm, eternally to our conceptual scheme, that e are many propositions stated in oclid's Elements? Is not Moore, perhaps, otroducing idle concepts not found in our e-Philosophical conceptual system? Are protestants against conceptual idols to be classed with the conceptual puritans who deny the existence of, for example, num- bers? These are hard questions, raised by reflection on Ayer's work. Perhaps he will sometime give us a more sustained treatment of them. Perhaps he should do so, even though he holds that in the end ontological decisions are not very important; for before we can wholeheartedly agree with him we still need to understand them better.