Summary: a large chunk of the history of Western philosophy is about finding out by what kinds of less conscious algorithms does the human mind arrive to certain intuitions.

In Plato's Republic, Socrates runs around Athens talking with people, trying to find an answer to the question: "What is justice?" Two and half thousands of years later we still don't have a truly definitive answer. We can spend another thousand year or two pondering it, but I suspect it would be better to reformulate the question in a more answerable way. So let's look at what Socrates is trying to do here, what his method is and what is actual question is!

It is not an empirical, scientific question that can be answered by observing something whose existence is independent of the human mind. Rather the question is about a feature of the human mind, not of a feature of the external reality out there.

However Socrates is not simply conducting an opinion survey. He is not content simply finding 74% of Athenians think justice means obeying laws. Socrates also argues against definitions of justice he considers _wrong_.



So, apparently, justice in this question relates to something that does not exist outside the human mind, but we can still have wrong opinions about it.

The method Socrates is employing is the following. He assumes when people see an actual action, they can intuitively judge it just or unjust and that judgement will be seen as _correct_. Well, not always, but at least when they are dispassionate, and have no vested interest either. So according to Socrates, any definition of justice can be tested by thought experiments that are sufficiently dispassionate and disinterested for the audience that they will actually use their Justice Sensors to form a judgement about them, and not, say, their passion like anger or greed, or their interests.

What Socrates is doing here, then, is asking people to make an algorithm that predicts what acts will a dispassionate and disinterested observer find just or unjust.

Example: "I think justice is paying debts." "Okay dude, but what if you borrowed a sword from a friend and now you see he is really mad at people and wants to go on a murderous rampage. Would it be just / righteous / correct to pay the debt and return the sword now?" "Uh, no."

This means: "I propose this algorithm." "This algorithm predicts you would find hypothetical situation X just. Would you?" "Uh, no."

The big question: is he looking for any algorithm that _happens_ to predict human intuitions of justice, or looking for the algorithm the human brain _actually_ uses? Well, they probably did not know much about algorithms back then, and they considered the brain an organ for cooling the blood but from our own angle, since we know the brain uses algorithms, any algorithm that predicts really well what another algorithm does is more or less the same algorithm.

So, "What is justice?" roughly means this: "What algorithm does our brain use when we intuitively consider something just or unjust?"

I am not claiming you can reduce all of philosophy to this, but apparently a significant chunk of Western philosophy ("footnotes to Plato") you can.

If we see philosophy this, we can also see better how does it overlap with yet why is it distinct from science. The basic ideas are the same: propose hypotheses, test them with (thought) experiments. The difference is that science is focused on looking outward, on the observable reality outside the mind. When science wants to learn about the brain, it invariably treats it as an external object and manipulates and observes it so, for example, looking at what areas of neurons light up under an fMRI scan.

Philosophy is, apparently, a form of cognitive science, a way of learning about the brain that looks inward, not outward, here the experimenters observes his own brain from the inside, and generally tries to consciously notice the subconscious algorithms his brain works with.



This is also why philosophy can feel so "truthy" on the gut level. You can have these kinds of "I knew it! I knew it all along, dammit, just did not connect the dots!" types of euphoric heureka experiences (or: "how could I have been so stupid" types of experiences) far more often in philosophy or math than in the empirical sciences such a biology, because here you study how your own brain works and you study it from the inside. It is about one part of your brain learning how the other part works. (OK, phyiscs is empirical enough and yet it happens. But the point is, it does not really happen in the empirical part of physics like measuring the weight of a particle. It happens in the mathemathical parts of physics.)