What is Logical Positivism?

"Logical positivism" is a school of thought in philosophy that reached its peak in the 1930s, and subsequently faded due to significant objections to its central tenets. However, even if it did not succeed in its entirety, it did articulate some important ideas that have remained deservedly influential in philosophy.

Logical positivism was originally most associated with Germany and Austria, but it soon had its proponents in the English-speaking world as well.

Prominent logical positivists included A.J. Ayer, Rudolf Carnap, Otto Neurath, and Moritz Schlick.

The main element of logical positivism is what is known as the "verifiability theory of meaning." According to this principle, every claim, every declarative sentence, falls into one of three categories: Either it is true or false by logic or definition alone, or it is an empirical claim that is in principle verifiable or falsifiable via empirical observation, or it is meaningless. (Or it could be reducible to one of these, or be a combination of these.) Let's look at each of the three a little more closely.

Examples of sentences that are true or false by logic or definition alone would be:

* "That bachelor is married."

* "All triangles have three sides."

* "Fred is from the planet Epticon and it is not the case that Fred is from the planet Epticon."

The first is false by virtue of the definition of "bachelor." The second is true by virtue of the definition of "triangle." The third is false by virtue of the law of logic that any sentence of the form "p and not-p" is false.

(It's always assumed in cases like this that you're not "cheating" through equivocation or other "tricks." For instance, "I named my dog 'Triangle,' and he doesn't have three sides," or "What if we're talking about two different Freds?" don't count as valid counterexamples.)

For empirical claims to be verifiable or falsifiable in principle, they need not be verifiable or falsifiable in practice, but we need to know what would constitute verification or falsification. "Julius Caesar weighed more at noon twelve days after his 22nd birthday than he did at noon thirteen days after his 22nd birthday," is something we'll never be able to establish, because no one kept records of Caesar's weight every single day of his life, even assuming there were any scales precise enough to make measurements we could be confident of to settle this matter. But it's still a meaningful empirical claim, in that we know what kind of evidence it would take to verify or falsify it, even though we don't have that evidence or ever expect to. We don't know if it's true or false, but we know what it would mean for it to be true and how that could be established in principle, and we know what it would mean for it to be false and how that could be established in principle.

Which brings us to the third type of sentence, which is meaningless. Consider the claim "Tuesday weighs more than the square root of 3." The problem here isn't a practical one. It's not that Tuesday is absent now and we're no longer in a position to weigh it, nor that the square root of 3 is awkward to fit on a scale, nor that they're so close in weight that technology hasn't yet produced a scale that can make sufficiently precise measurements to say which is heavier. The problem is the sentence doesn't mean anything. It sort of looks like it does from its form, but days and numbers don't have weights-there's nothing even in principle that could be done to determine which one weighs more.

Logical positivism turned out to be quite radical in its way. For it didn't simply argue against certain claims, but it asserted that they were literally meaningless. In fact, much of philosophy, much of religion, for that matter plenty of the beliefs of lay people were, according to logical positivism, not just false, not just mistaken, not just incomplete, but basically gibberish.

For instance, if you were to say to a logical positivist "Everything that happens is God's will," he would likely ask you to explain what you mean by that by specifying what would have to happen to verify it and what would have to happen to falsify it. How can it, in principle at least, be tested? If it turns out that not even in principle is there anything empirically observable that would count as falsifying it, then the logical positivist's response would be "OK, then in effect you're saying nothing at all when you claim that."

Logical positivists delighted in going through the works of speculative philosophers and mystics and such from throughout history, and picking out sentences that have no discernible meaning because they are not logically, definitionally, or empirically true or false, even in principle. Like "The world is an unfolding of infinite thought," or "The nothing nothings," or "The Essential exists outside Time." Unless these turn out to be, say, metaphors that can be translated into sentences that can in principle be verified or falsified by logic, definition, or empirical observation, they're gibberish. They're no different from somebody saying "Bibbity, bibbity, bibbity, bibbity."

For that matter, things like morality and aesthetics are out the window, again unless their claims can be converted to something meaningful according to the logical positivist criteria. Either "abortion is wrong" and "the Mona Lisa is beautiful" turn out to be shorthand ways of expressing empirical claims or sets of claims, or they say nothing.

Substantively they're gibberish, that is. They might still have some emotive or other function, but they have no content. Just like murmuring "Bibbity, bibbity, bibbity, bibbity" in a soothing voice may have some emotional effect, but it's not making a literal claim that even in principle could be true or false.

Alas for the logical positivists, they were seemingly tripped up by their own rules. Consider the sentence: "Every claim is either logically or definitionally true or false, or empirically verifiable or falsifiable, or meaningless." Is that sentence itself true by definition? Is it a logical tautology true by virtue of its structure alone? Is it something that one can in principle gather empirical evidence for or against to show whether it's true or false? The answer to all three questions arguably is "no."

So by the process of elimination, is the verifiability theory of meaning itself just an empty, meaningless string of words?

This and other concerns influenced most philosophers away from any kind of pure logical positivism. However, it's central message, that much of the time we think we're asserting meaningful claims, we're likely doing nothing of the sort, is almost certainly accurate. With things like religious claims, metaphysical claims, alternative medicine claims, etc., as often as not the most relevant question to ask isn't "Is that true or false?" but "Does that even mean anything?"

If you believe something, but you really can't identify any way the world would be different if it were true versus if it were false, there's a pretty good chance there's nothing to your belief beyond maybe some pretty words that make you feel good to claim to believe.