TRUTHLIKENESS

An inquiry is a search for the truth of some matter. A person may embark on an inquiry for all manner of reasons: to relieve boredom, to satisfy a client, to help make gadgets, to win the Nobel Prize, to get a raise, or to impress his friends. Still an inquiry qua inquiry is a search for truth, and success is determined by the extent to which the inquiry reveals that truth. Scientific inquiry may be special in various ways, but it shares with inquiry in general this constitutive goal of revealing truth. On the face of it, scientific inquiry has been an astonishingly successful enterprise. There is scarcely an aspect of contemporary life that, for good or for ill, is not pervasively and deeply penetrated by the discoveries of the scientific enterprise. Paradoxically, its most dramatic successes have often been initially promising theories subsequently shown to be false. How can the apparent success of scientific inquiry be reconciled with its embarrassingly regular failure to realize the constitutive goal of truth? One might – in a spirit of conceptual vandalism – drop truth and reframe success in terms of empirical adequacy, the discovery of useful theoretical tools, or the production of handy technology. Alternatively, one could respect truth as the goal and entertain the concept of truthlikeness, or verisimilitude. For if some false propositions are closer than others to the truth, progress towards the goal of truth through a succession of false, or even falsified, theories is entirely possible. At a purely common-sense level some propositions do seem closer than others to the truth. Assume that there are just eight planets (Pluto having been recently stripped of full planetary status). Then the falsehood that there are 7 planets seems closer to the truth than the ancient hypothesis, also false, that there are 5. Some truths seem closer to the whole truth than other truths: the truth that there are between 7 and 9 planets seems closer to the whole truth than the weaker truth that there are between 1 and 100 planets. And some falsehoods seem closer to the truth than some truths: the falsehood that there are seven planets seems closer to the truth than the tautology – that there is some number or other of planets. So the familiar dichotomy of propositions into truths and falsehoods is compatible with a more fine-grained partition, one that reflects degrees of truthlikeness. The logical problem of truthlikeness is to provide an account of the concept and to explore its logical properties. However, the concept would be practically useless if we had no epistemic handle on its application, and it would be theoretically uninteresting

unless we could grasp the value of truthlikeness. So the logical problem intersects with problems in both epistemology and value theory. A solution to any one of these problems of truthlikeness will have ramifications for the others. While the concept of truth has been a focus of philosophical scrutiny for millennia, the concept of truthlikeness has come under the spotlight only relatively recently, and it is still rare for philosophers to devote much attention to it. This “latecomer” status is not hard to explain. The problem becomes urgent for a particular combination of realism, fallibilism, and optimism, which is itself of relatively recent vintage. Epistemology since Descartes has been a reluctant and fitful retreat from the ideal of infallible knowledge. It is replete with attempts to establish a solid beachhead against skeptical assaults, but sadly these have failed to guarantee certain knowledge of anything terribly interesting. Further, the history of science is a parade of promising theories eventually shown to be false. (Consider theories of the motions of the planets, from Ptolemy to Newton.) So, for both philosophical and historical reasons, we are all fallibilists now. Fallibilism would not by itself compel us to tackle the problem of truthlikeness. One could, instead, abandon realism. Radical anti-realists (postmodernists, say) would have little use for the concept; and subtler, more reasonable, anti-realists might simply sidestep the problem. Suppose truth is taken to be whatever scientific inquiry will yield in the limit. A long preamble of false theories wouldn’t be so troubling, since we could know a priori (by semantic fiat) that scientific inquiry will reveal the truth in the long run. The problem is pressing only if we yoke fallibilism to a robust realism – that there is a verification-transcendent truth of the matter, and we cannot be certain that, even in the limit, scientific inquiry will reveal it. This is still insufficient to force us to tackle the problem, for we could simply abandon the pretension that the scientific enterprise can make progress. So we need, in addition, a certain optimism: an affirmation of the promise of progress. These three necessary conditions for the problem are also jointly sufficient. The logical problem of truthlikeness should be on the agenda of every realist who is also a fallibilist and an optimist.