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Subject Area: Political Theory

Necessary Truths and Reality - Leonard P. Liggio, Literature of Liberty, July/September 1978, vol. 1, No. 3 [1978]

Edition used:

Literature of Liberty: A Review of Contemporary Liberal Thought was published first by the Cato Institute (1978-1979) and later by the Institute for Humane Studies (1980-1982) under the editorial direction of Leonard P. Liggio.

Part of: Literature of Liberty: A Review of Contemporary Liberal Thought, 20 vols. 19781-982

About Liberty Fund:

Liberty Fund, Inc. is a private, educational foundation established to encourage the study of the ideal of a society of free and responsible individuals.


Necessary Truths and Reality

Douglas B. Rasmussen

  • Marquette University

“Logical Possibility, Iron Bars, and Necessary Truth.” The New Scholasticism 51 (Winter 1977): 117–122.

Some academic disciplines such as economics and political philosophy suffer acute methodological embarrassment when they claim their arguments (e.g., about human nature) are simultaneously necessary truths and factual. This embarrassment arises from the debatable dichotomy which asserts that any necessary truth must be non-factual and merely formal.

Necessary truths, in this view, say nothing about the real, factual world and are necessary only for formalistic reasons of definition and stipulation. Conversely, factual matters (e.g., an iron bar sinks in water) are viewed as non-necessary or contingent: they happen to be so, but, without definitional contradiction, we can conceive of the essence of iron bar and not include the property of sinking in water. Apparently, it is “logically possible” for any given factual state of affairs to be otherwise. Such ontological facts would seem too contingent to firmly support necessary truths.

We can challenge this dichotomy that separates the real world of fact from the necessary world of certain knowledge and necessary truths. We can argue against the supposition that factual matters must be contingent. Statements can, in fact, be both necessary and ontological or factual truths simultaneously.

A valid notion of “logical possibility” requires us to consider all the known data of a certain state of affairs (including the actual specific gravity of iron). We must also look at actual possibility rather than postulate a “possibility” that deliberately ignores known facts (e.g., iron sinks in water). Thus, valid logical possibility considers all the known data. By contrast, the invalid notion of logical possibility (which holds that factual statements about the world must be non-necessary) can exist only when we consider something (say, iron) in isolation from all that we do know about it. The full, known reality of anything forbids us to consider it other than it is.

Next, the valid sense of logical possibility may be joined with Henry Veatch's view of “what-statements” as necessary truths in Two Logics: The Conflict between Classical and Neo-Analytic Philosophy (1969). What-statements (or essential definitions of things) can be necessary truths about the world without claiming absolute, dogmatic infallibility and irreformable omniscience. The possibility that future events may make us revise our essential definitions does not entail that we can pronounce only contingent truths about the world.

Further discussion of natural necessity may be found in Fr. Wallace's book on Causality and Scientific Explanation and in Henry Veatch's review article of R. Harré and E.H. Madden, Causal Powers: A Theory of Natural Necessity [The New Scholasticism 50 (Autumn 1976): 537–541].