The unbridgeable gap between ontology and science leads to another key theme in Jaki's philosophising - the place of quantities and man's quest for certainty. For some time certainty has been taken as synonymous with numerical accuracy and this reached its apex in the mechanistic philosophy where perfect precision in measuring was identified with full causality in happening. (c.f. Numbers Decide p. 18)
Aristotle noted long ago that quantities were different to his other nine categories in that "the category of quantity does not admit variation of degree". (Means to Message p. 33) Indeed this difference has become the principal message in Jaki's later works. He states that "the two realms of quantities and qualities live on in a splendid conceptual isolation from one another... no conceptual acrobatics can build a smooth transition between them". (A Mind's Matter p.172) However, Jaki always examines the limitations of quantities not least the fact that "the definition of a number can only be given in non-numerical terms." (Science and Religion: A Primer p.5)
Exactness, accuracy, precision and specificity are often used inter-changeably in connection with certainty and reality. However, since qualities lack the measurable clarity of numbers, advocates of scientism do not take them to be real and consequently not important. (c.f. A Mind's Matter p. 173) Past attempts to shoehorn qualities into quantities have invariably failed since, for example, "no measure, unless it is rather arbitrary, can be given of the point where a stick turns into a pole, a knife into a sword, a hut into a house, a lake into a sea, a hill into a mountain, a path into a road. (Means to Message p. 35)
Qualities may be indeterminate "patches of fog" but their reality is assured since ontological being can be exact independently of quantities. Five cannot be more or less five, but the real too, can neither be more or less real. While it is the numerical precision of science that makes it so effective, Jaki reminds us that "the connection between calculation and that reality is provided by something called philosophy and not physics" (Galileo Lessons p. 23)
Numerical exactness depends upon ontological exactness and not the other way around, unless one wants to play a dangerous game with reality, to recall Einstein's phrase. Instead, "at the very start of his work the scientist must answer affirmatively the question. is there matter? Both the question and the answer are very philosophical." (Questions in Science and Religion p. 17)
Jaki constantly reminds us that ontology is the bedrock for the river of change from which we recognise qualities and quantities.
Before there are ideas about reality there has to be a reality to be registered and that this reality exists regardless of whether we register it or not. This however, assumers that there is something fundamentally constant in reality even though it shows changes. That fundamental feature is much more than that material reality which is always measurable, which makes science possible and also exhausts it. But precisely because of this science cannot exhaust reality as such. [Numbers Decide p. 25]