Is epistemology—the study of knowledge, how knowledge is acquired—really the same as logic? If not, what are the differences between epistemology and logic?
By logic, I mean the art by which we order or thoughts or the "science of reason", as St. Thomas Aquinas calls it in the proem of his commentary on Aristotle's Posterior Analytics.
One place to look for an answer to this is in Stephen E. Toulmin’s The Uses of Argument, last updated in 2003, Cambridge University Press.
Toulmin recognizes that there has been a difference between logic and epistemology. Logic has been concerned with analytic issues where standards of entailment predominate while epistemology has a broader reach trying to justify substantial assertions using field-specific standards.
His view of how things should be is pertinent to your question: (page 234)
To begin with, then it will be necessary to give up any sharp distinction between logic on the one hand, and theory of knowledge on the other.
That is, he claims we need “a rapprochement between logic and epistemology which will become not two subjects but one only”.
From Toulmin’s perspective the answer to your question whether epistemology is the same as logic is Yes.
An epistemology is a method of acquiring knowledge. One possible epistemology, for example, might be to meditate and wait for divine inspiration. Another might be to guess or flip a coin. You might poll random strangers. These are not particularly good epistemologies, but they are epistemoligies. More useful epistemologies tend to use tools like Logic and Science.
Logic, then, is a tool one might use for espistemology. As is a magic 8-ball. I'll let you decide which you prefer.
Epistemology deals all manners of knowledge and tools for understanding and acquiring knowledge. It uses logic(analytic reasoning) but also can make use of gnosis(intuitive or ecstatic reasoning). For more info on and the difference between logic and gnosis, I refer to the contemporary philosopher Michael Meade. He is specifically a mythologist, but mythology is very much concerned with epistemology, it combines study of epistemology with storytelling.
In short, no. Epistemology is not a synonym for logic.
Epistemology is a philosophical inquiry concerned with the object knowledge, its construction, knowers, and knowing.
Assuming you take positive positions on the questions of whether knowledge exists, whether it corresponds to some objective reality, and further still, whether it is gettable by humans, then logic can be understood as one way of getting knowledge about the world.
I think it is fine to think of it as a set of rules used to systematically evaluate the truth status of knowledge claims or propositions. Of course, you can understand logic as abstractly and symbolically as you wish, as in the case of mathematical logic.
Some people think logic is the right way to get/evaluate knowledge, others think it is the best way, while others believe it is the only way. And, of course, there are others still with different opinions about its strengths and weaknesses as way to knowledge.
▻ OUTLINE OF EPISTEMOLOGY AND LOGIC
◆ Epistemology (logos tes epistemes) is the philosophical inquiry into knowledge : the origin of knowledge, the place of experience in knowledge, the different kinds of knowledge, the relation of knowledge to certainty, the possibility of knowledge (the challenge of scepticism). These and such like matters.
◆ Logic (logike, logos) is concerned with the rules of valid inference, the forms of valid inference (modus ponens, modus tollens, the syllogism, &c.) and with relations of implication, consistency, contradiction & self-contradiction, and independence that hold between propositions or sentences. Rough and unpolished as this characterisation is, it is broadly accurate. It is also broad enough to accommodate the Questioner's explication of 'logic'.
▻ INTER-RELATIONS - YES
Given these accounts of the two inquiries, there are certainly inter-relations between epistemology and logic :
☛ I can't know that p is true if p is a self-contradiction, for one example. I can't know that S is both p and not-p in the same respects at the same time, for another.
☛ Equally I can know that modus ponens is a valid rule of inference.
☛ There can be and is an epistemology of logic, asking how we know or can know e.g the validity of rules of inference.
☛ And there can be and is an epistemic logic, which represents epistemic relations logically :
Ka (φ → ψ) → (Kaφ → Kaψ)
That is to say that if a knows that φ implies ψ then if a knows that φ, this implies that a also knows ψ.
I'm not entirely sure about this. Suppose a fails to draw out the implication for whatever reason ? But I don't commit myself to the example; I use it just as a case of how epistemic relations can be 'logicised'. It does, however, introduce another interrelation : my 'logicisation' example, when a does draw out the implication, relies on a's knowing the logical consequences (or at least this logical consequence) of what he knows.
▻ IDENTITY - NO
So there are cross-connexions. But I can't see that logic and epistemology are identical - one and the same inquiry.
◆Logic as formal
This is because logic is formal and in certain respects independent of truth. I'd better be very careful in explaining what I mean by this. Take the following example :
Napoleon was a Spaniard
All Spaniards are over six feet tall
Therefore :
Napoleon was over six feet tall
Truth comes in because the conclusion cannot be false if the premises are true. But both premises and conclusion are false. If logic can generate falsity in this perfectly valid way, it hardly facilitates the acquisition of knowledge since knowledge cannot be false.
◆Logic only recycles what is already known
The identification of epistemology also fails insofar as the syllogism does not and cannot generate knowledge :
All men are mortal (suppose we know this)
Socrates is a man (suppose we know this)
Therefore :
Socrates is mortal
The conclusion, which follows validly from the premises, recycles but embodies no knowledge not present or implicit in the premises. The conclusion of a syllogism, if not this one, might be psychologically surprising but it contains no new knowledge.
▻ REFERENCES
Simon Blackburn, Oxford Dictionary of Philosophy, Oxford : OUP, 1996, 123 & 221-2.
R. Audi, ed., The Cambridge Dictionary of Philosophy, Cambridge : CUP, 1996, 233-8, 440-5.
Epistemology is the the investigation/study of the meaning of "Truth". I think the term you are alluding to in the current context may be the study of "Knowledge" which, correct me if I'm wrong, is Ontology. I.e. what is the actual theoretical limit of possible knowledge (ontology), as opposed to "is it knowledge or not" (epistemology)?
Of-course neither are "synonymous" with logic as logic is part of the toolkit required to perform the aforementioned investigation(s).
Or are you suggesting that all truth and knowledge can ultimately be arrived at through a process consisting purely of conditional branching (logic)?
