This question began with the following quote from John Paquette:
The following response came in:
You can learn a lot about birds qua birds before you ever learn about the existence of a specific kind of bird called "robin". You may never have seen a robin before making the (presumably) valid induction that female birds lay eggs. Induction does not require exhaustive knowledge of the class of entities (e.g. birds) being induced from.
Deduction tells you, specifically, that your general conclusion about birds applies to the new subclass of birds, "robin", that you have just learned about.
Deduction: THIS is one of THOSE. Qua one of THOSE, X is true of it. Robins are birds, qua birds, robins lay eggs.
This question pertains to the role of deduction in gaining knowledge. The topic is clouded somewhat by terminology such as "produce truth" (truth is discovered and identified, not "produced"), and by a distinction between "specific truth" and "general truth" that isn't clearly defined unless "general" just means a class, and "specific" means a class member or instance.
As the question points out, the egg-laying example has a basic problem: egg-laying is arguably an essential defining characteristic of birds, in which case one needs to examine Robins first, before concluding that they are birds, to determine whether or not they reproduce by laying eggs. On this view, if female Robins don't lay eggs, then they're not birds.
But suppose the example is changed a little, as follows:
This example illustrates Objectivism's basic perspective on how man gains knowledge:
OPAR explains the role of logic in Chapter 4, "Objectivity," in the section titled, "Objectivity as Volitional Adherence to Reality by the Method of Logic." Logic is not a means of "producing new truths." It is a tool to assist man in the process of integrating his observations and immediate identifications. (Refer also to the sections titled, "Concepts as Objective," "Knowledge as Contextual," and "Knowledge as Hierarchical." For contrast, the chapter ends with "Intrinsicism and Subjectivism as the Two Forms of Rejecting Objectivity.")
The ways in which specific observations and identifications may be connected to other observations and integrations are not necessarily self-evident without cognitive effort. The process of integration -- and of seeking out and correcting any contradictions -- can often reveal connections that one may not initially have comprehended, thereby broadening and strengthening one's integrations. Logic doesn't "produce" new knowledge; it only helps man to see connections and possibilities (or clashes) he may not have recognized previously.
Regarding birds that may or may not lay eggs (i.e., types that produce offspring by laying eggs), it is possible for a new concrete to fit within a previously formed concept in terms of the essential distinguishing characteristics of the units of the concept, yet differ from the other units in some significant way. An type of animal that looks like a bird and acts like a bird but doesn't lay eggs like a bird would be an example. Such an exception case might well turn out to be sufficiently different from birds to warrant a new classification of its own, for a type of animal not previously known. The mere fact that it matches an existing concept in all ways previously known and identified as fundamental to the concept does not prove or mandate that the new type of concrete must match in other respects. Whether or not it does match, and how closely, is for man to observe and identify by looking at it directly and more closely. Reality always is what it is, and man's concepts need to be adjusted and adapted accordingly as the evidence warrants.
(Technically, egg-laying cannot be an essential definining characteristic of "bird" because half of the bird population doesn't qualify, namely, the male half. And even among females it is not necessarily true that all females actually perform egg-laying. Some may fail to find a mate and build a nest. What the females possess, if they are not defective, is an egg-laying capacity, which may or may not be fully functional in any particular female.)
A comment asks:
Are you saying that you can be certain of a particular piece of knowledge even though you can't be certain that your knowledge won't change if your context changes in the future?
The answer is yes, exactly. It should also be added that the kind of context change involved here normally happens very infrequently and/or slowly. It's not something one normally needs to make a special effort to remember and acknowledge. One need not go around continually qualifying one's claims as subject to a specific context if the context and the dependency are already understood.
OPAR explains the Objectivist view of certainty and absolutes in Chapter 5, "Reason," in the section titled, "Certainty as Contextual." Pages 172-174 observe:
Man is a being of limited knowledge -- and he must, therefore, identify the cognitive context of his conclusions. [...]
This OPAR discussion goes on to explain further what is meant by "absolute" (p. 175):
The modern definition of "absolute" represents the rejection of a rational metaphysics and epistemology. It is the inversion of a crucial truth: relationships are not the enemy of absolutism; they are what make it possible.
Further overview of the Objectivist perspective on certainty and absolutes can be found in The Ayn Rand Lexicon under the topics of "Certainty" and "Absolutes." There is also illluminating discussion by Ayn Rand in ITOE, 2nd Ed., Appendix, section titled, "Scientific Methodology."