Science in Christian Perspective

Letter to the Editor

Leiths Law

 George Mavrodes (JASA, December 1966) finds some absurdity in my ideas about the absurdity of certain aspects of the thesis of apparent age, assuming (he says) that he understands these ideas. I think that he  does, although I confess that I would have thought it was rather less difficult to arrive at this understanding of what I said. However, I now fail to see how my argument leads to the absurd conclusion which George derives from it. Let me outline the relevant ideas and "fundamentalist" terms at that time, completely without the non-sequitur should be clear.

Firstly, I take it that there are logically impossible propositions which are also meaningful. It appears to me that the proposition "the knowable universe began with the appearance of considerable age at some time rather more recent than this apparent age" is both syntactically sound and without self-contradiction, and thus it is meaningful. Assuming this, until I am shown otherwise, I am also of the opinion that all the evi dence appropriate to the proposition stated above, if this evidence is the knowable universe, is at the same time evidence corroborating and evidence falsifying it.

  Now I can conceive of some source, such as visions or written revelation, indicating that the knowable universe began X years ago, although propositions about such matters have their own problems. I might also  accept, assuming these problems are soluble, the truth of such an indication if the credibility of the source and its interpretation seem well founded. Again, I might imagine some age Y for the universe as the last (not just the latest) word of science on the subject but this age cannot, since it includes all the relevant observational evidence and a correct understanding of all the relevant laws of nature, show a difference between the real age X and the apparent age Y. Thus I can accept the truth of the proposition "the universe has an age V from a non-observational source of evidence and the truth of "the universe has an age Y" from scientific evidence.

However, I consider the conjunction of these propositions within the language of science to be logically impossible since all the scientifically relevant evidence, the knowable universe, both corroborates and falsifies the proposition "the universe has an actual age X and the appearance of a greater age Y". Of course, I may define "relevant evidence" to include sources other than the knowable universe since I take those sources, e.g. visions and written revelation, not to be part of the universe with which science, as normally understood, deals in determining the age which we seek. If this new definition is permitted, and it certainly may be even by a scientist, then the proposition is logically possible and may be true. I take it to be very likely false upon examining these additional sources of evidence with which I am familiar.

Thus logical possibility seems to depend upon what one considers evidence relevant to the truth or falsity of a proposition. I feel free to consider evidence which is not part of science as it is normally understood but I cannot introduce such evidence into that science. The scientist dealing with the physical universe is forbidden to use everything which he claims to know when conversing within the discourse of his discipline, although I hope he can still talk about his discipline, its limits, and what may lie beyond that discipline. The philosopher and others will do it for him if he doesn't. His prejudices and abilities may limit his interests and resources here but I cannot agree with George that it is his scientific concerns which restrict him. Rather, those concerns are limited by, among other things, decisions as to what is to be taken as relevant to them.

I take this to be something of a mixed blessing in the history of science when, for example, it delimits biology from chemistry in artificial ways, but no clear reason for diluting the general distinctions as to the sorts of relevance which I have been discussing. Perhaps George sees Leith's Law of demarcation as restricting the whole man, but surely there are useful and perhaps ontological differences between the realm of physical nature and the non-physical which one takes into account when one is a whole man doing scientific work. I find this a meaningful proposal and not at all absurd.

T. H. Leith,
Associate Professor of Natural Science
York University,
Toronto, Ontario