If philosophy is the rational investigation of truth, how is it different from science or mathematics? Is philosophy based at some level on a subjective feeling? If so, how is it different from religion or spirituality in this respect?
I would suggest that religion is an application of philosophy to a given faith or history. And science itself is at root the religion that arises from a faith in naturalism.
We do not disown theologies in philosophy, within their own cultural constraints they are valid philosophy. And all of our very early philosophies were very much associated directly to given quasi-religious notions.
We consider Platonism a philosophy, but beefed up just a little into Neo-Platonism, it is a religion. Was some specific addition between these two somehow the straw that broke the camel's back? No, Platonism is already a sort of personal religion. It just arose out of a single man's head, rather than a cultural tradition. And it is oddly compelling in a way that makes it easy to clip some corners and render it "consistent enough" with many other religions to make it worth keeping around.
Everything that happens does so in some historical tradition, with some basic set of ultimately un-analyzed assumptions. So in essence systematic philosophy is, as a whole, a collection of ad hoc theologies.
The constraints that separate where one or the other theology applies do not involve the whole religion, just its central principles or the observed 'facts' of its interpreted history. All the rest of any given religion is a collection of theologies, or involves more basic philosophy like logic, ethical analysis and ontological exploration applied within the frame of some theology of the religion. Even the raw experience of the religion in mysticism or personal investment is really an aesthetic engagement attached to a theology that shapes its details. The amalgam of all Hindu theology is Hinduism. The amalgam of all Christian theology is Christianity.
The basic facts cannot be analyzed philosophically, and make up the 'core faith' of the religion, which sets it apart from other religions. But even the process of analyzing and isolating that core is a philosophical endeavor. Not all Christians or Hindus take the same axiomatic base to their overall religion, and not all of those with disjoint core notions would exclude others from the 'big tent' of Christianity or Hinduism. So theologies can be tied together in complex ways and they can overlap or include large parts of one another.
Science is something that we seem to be able to share across most religions. But that is because all religions have to enclose a philosophy consistent with some contact with natural reality. If the religion just consistently disowns reality (like raw Buddhism), it can get along, but variants of it will arise that do not do so, and those who stick to the anti-realist standards will unconsciously adopt one of those variants to get through life, even while considering it ultimately incorrect.
But at root, there is no reason to have faith in our experience of nature. We just do, because we are animals and animals are natural beings. So the philosophical explorations that arise from that root faith are not in essence different that those of a 'real' religion. They are just much more likely to be consistent with some pocket in each other faith.
Science is a systematic method of increasing knowledge involving testable hypotheses and replicable methods.
Philosophy is sometimes known as the "mother of sciences," it considers questions outside the reach of currently accepted reliable scientific methods. Not all philosophies do involve the rational exploration of truth, which would better be described as a philosophical approach, rather than the philosophical approach. Philosophies can be highly ordered and elaborated, but they are not generally verifiable in an objective fashion (this does not mean they are worthless or wrong). Successful philosophical consideration of a realm of inquiry can produce a science (for example, physics, astronomy, logic, psychology), which is why the founding figures of various sciences were often considered philosophers in their day.
Religion is a set of rituals, practices, structures and beliefs, typically connected with a theology, which is a philosophy about God (although there are some non-theistic religions). If theology was a science, religion would be a technology.
The distinctions can be made in virtue of how much dogma and empirical evidence are involved, but philosophers have pointed out that the lines of demarcation are rather blurry, like the distinction between bald and not bald.
Philosophy involves very little dogma and very little empirical evidence; it is the art of rational conjecture. Philosophers seldom agree with each other because common premises are few and far between. In the realm of opinions freedom should be absolute because the opinion doomed by one philosopher may be perfectly acceptable by another philosopher. Bertrand Russell preferred a quarrelsome atmosphere in philosophy and refused to play the authoritative role at the height of his career; he was generous to his attackers and lavished compliments to anyone who demonstrated some understanding of his philosophy.
Science relies heavily on empirical evidence. Nevertheless philosophers have pointed out that there are hidden faiths in scientific knowledge; the empiricist creed that all knowledge is derived from sense-experience is itself a dogma. Because of these all-agreed-upon common criteria, scientific methods are widely accepted in scientific community, and peer review is a reliable procedure to ensure the quality of scientific work. Hidden faiths in empirical knowledge do not license other groundless faiths; empiricism too is not immune to doubt - this is what faith implies.
Both philosophy and science are highly tentative, subject to revision based on new evidence.
Religious pillars are dogmas. Paradoxically and by the same standard, scepticism can also be called a religion. The dogma that is fundamental to scepticism is this:
It is undesirable to believe a proposition when there is no ground whatever for supposing it true. (Russell. On the Value of Scepticism)
Bertrand Russell was the kind of philosopher who sifted through systems of beliefs and pointed out what were implicitly assumed a priori, then went on to reduce the number of postulates to bare minimum. This pattern of thinking recurred in his Critical Exposition of Philosophy of Leibniz, his mathematical philosophy and his theory of knowledge.
Science, or the scientific method, limits itself to removing unreasonable hypotheses based on meassurment and observation (direct perception).
Religion (theology) usually allows truth to be discovered not just through direct perception, but through inference, testimony of the wise, scriptures, prophecy etc. (religion as the social, economic, legal, historical etc aspects of a society through time, are not related).
Philosophy, or the philosophical method, is not much different to the scientific method, but it follows the laws of logic more than the laws of mathematics (which are related).. It usually states some perceived a-priori truth, whilst science is by definition a-posteriori.
Though in truth, any null hypothesis at the beginning of a scientific experiment parallels the a-priori thinking of the philosophical method, whilst the actual meassurement and analysis, the a-posteriori of the scientific method... Philosophy and Science are really two sides of one method.
(Philosophy provides more rigour than theology, but in the end whether Kant's categorical imperrative or Tawheed - tend to embrace the unverifiable and unfalsifiable, metaphysics (beyond physics, or beyond observation). Philosophy does tend to stray into metaphysics a lot more than science, but the latter is not bulletproof from that either (de-Broglie Bohm, Einstenian realism, string theory))
Faith & reason
To understand the difference between religion, ideology, philosophy and science, it is important to first distinguish between two fundamentally different approaches towards the interpretation and analysis of information : faith & reason.
Wikipedia uses the following definition :
Faith is confidence or trust in a person or thing; or the observance of an obligation from loyalty; or fidelity to a person, promise, engagement; or a belief not based on proof; or it may refer to a particular system of religious belief, such as in which faith is confidence based on some degree of warrant.
Faith is typically a subconscious process, that works through emotion. It is typically driven by processes at the instinctive or intuitive level that one is not consciously aware of.
Depending on who you talk to, being faithful is either considered a good thing or a bad thing :
I believe in Christianity as I believe that the sun has risen: not only because I see it, but because by it I see everything else.
― C.S. Lewis
Faith: not wanting to know what is true.
— Friedrich Nietzsche
When we blindly adopt a religion, a political system, a literary dogma, we become automatons. We cease to grow.
— Anais Nin
Wikipedia uses the following definition :
Reason is the capacity for consciously making sense of things, applying logic, establishing and verifying facts, and changing or justifying practices, institutions, and beliefs based on new or existing information. [...] The concept of reason is sometimes referred to as rationality.
Reason is a conscious process, that may or may not take emotions into account (albeit at a conscious level).
Some would argue that reason is higher than faith and that a great capacity for reason eliminates the need for faith :
The way to see by Faith is to shut the Eye of Reason.
— Benjamin Franklin
We may define ‘faith’ as the firm belief in something for which there is no evidence. Where there is evidence, no one speaks of "faith." We do not speak of faith that two and two are four or that the earth is round. We only speak of faith when we wish to substitute emotion for evidence.
— Bertrand Russell
All our knowledge begins with the senses, proceeds then to the understanding, and ends with reason. There is nothing higher than reason.
— Immanuel Kant
Others would argue that faith and reason are complementary. They would argue that faith can (and should) be used wherever reason does not provide us with answers :
Faith consists in believing when it is beyond the power of reason to believe.
Reason is our Soules left hand, Faith is her right, …
— John Donne
Faith certainly tells us what the senses do not, but not the contrary of what they see; it is above, not against them.
— Blaise Pascal
Religion, ideology, philosophy, science & pseudoscience
Religion, ideology, philosophy and science are different but related approaches to understanding the universe around us. Herebelow, I try to explain the difference, as well as the difference between what qualifies as science and what qualifies as pseudoscience.
Religions are humanity's first approach to understanding the universe. They typically start with a charismatic guru-type figure, like Zoroaster, Moses, Gautama Buddha, Jesus Christ, Muhammad, Joseph Smith and Bahá'u'lláh. Typically, these individuals were known for their great wisdom and were responsible for a major social overhaul that improved the lives of thousands (if not millions) of people in just one generation.
By becoming known as "saviors" during an era of great despair, subsequent generations started relying on words of their "savior", which was usually first past orally and later past in written form. Because it helped them survive and/or achieve social status, the words of the "savior" defined how people lived their lives.
Some religions allow for constant interpretation and re-interpretation of the words of the "savior". A typicaly example would be Judaism, where generations upon generations of rabbis have added their own interpretations of Judaic law to refine it or modify is for more "modern" times. As such, the original 10 commandments of Moses evolved into the 613 mitzvot, first mentioned in a sermon by 3rd century Rabbi Simlai, recorded in Talmud Makkot 23b. And even then, Judaic lore kept evolving with each generation of rabbis, with the most traditional form of European Judaism drawing heavily on the 16th century Lurianic Kabbalah.
Other religions allow little interpretation. One of the more extreme examples are Biblical literalists, who consider every word of the Bible as the literal word of the Christian God. Biblical literalism is mostly popular among Evangelical Christians, which is rather unpopular in Europe but very strong in the US. According to a 2011 Gallup survey reports, about 33% of the American population belongs in this category.
By heavily relying on the "revelations" of one or more charismatic figure, religions are meta-frameworks strongly rooted in faith. However, they can and often do involve reason to refine and update those revelations for later generations.
The "savior" upon which a religion is grounded can be deified by followers of that religion, but this isn't the care per se. Not all religions involve a "savior" figure that "supernatural" powers are attributed to.
Like religions, ideologies typically start with a charismatic guru-type figure : think of Karl Marx, Adolf Hitler, Mao Zedong or Kim Il-sung. Like religions, ideologies draw heavily on the words of those charismatic leaders. And like religions, ideologies are strongly rooted in faith.
So what's the difference between religions and ideologies? Some might argue that the only real difference between both, is that ideologies are secular. Ideologies do not presume the existence of magic or divine authority. Ideologies do not usually presume any correlation with supernatural.
However, this distinction is rather arbitrary and there are many shades of grey. For example, Hitler believed to be divinely inspired and the way Kim Il-sung is venerated and mythologised in North-Korea today can hardly be distinguished from the way Jesus or Muḥammad are venerated in their respective religion. So ideology could be just be the initial phase that every religion passes before it becomes a religion.
Philosophy is different from religion in the sense that it is not so much rooted in faith as it is in reason. While philosophy neither excludes nor requires faith, philosophy is an approach to understanding that focuses on reason.
While philosophy still approaches many charismatic figures from the past as authorative figures, those figures aren't given the same dogmatic treatment given to the charismatic founders of religious movements. Men like Aristotle, Kant or Stirner are treated more as sources of inspiration rather than authorities that are not to be questioned. This, in turn, makes philosophy more open to dissenting views and data that contradicts dearly held views.
Consistent logic is the very foundation of all philosophy.
Science takes the approach of philosophy a step further by rejecting all faith as a valid approach to the establishment of truth. Where philosophy only requires consistent logic, science adds to these requirements the need for empirical evidence and interpretation in accordance with the scientific method.
A claim is not scientific if it is not (1) supported by a consistent and logical interpretation in accordance with the scientific method, (2) either explicitly suggested or at least supported by empirical evidence as well as (3) consistent with the body of evidence established in accorandance with the first two principes.
If a scientist makes a claim that happens to be consistent with the first two principes but not with the third, he must first point out errors in the the body of evidence established in accorandance with the first two principes and correct those errors in a manner so his new claim is no longer incompatible with the third principle. By these means, science is self-correcting, which allows for the scientific body of evidence to be gradually improved.
It is important to distinguish science from pseudoscience, which involves any claim, belief, or practice presented as scientific, but which does not adhere to the scientific method. A field, practice, or body of knowledge can reasonably be called pseudoscientific when it is presented as consistent with the norms of scientific research, but it demonstrably fails to meet these norms.
To put it differently : pseudoscience is the disguise of ideology, religion or plain nonsense as science. Pseudoscience can be fringe, but it doesn't need to per se. Pseudoscience can be totally mainstream and it's possible for a claim to be both pseudoscientific and for it to be supported by the majority of the population.
For a claim to be pseudoscientific, it neither needs to be unpopular nor false. All it takes for a claim to be pseudoscientific, is for it not to adhere to the three principles (see above) that scientific claims need to adhere to. As a consequence, pseudoscience isn't always obvious to distinguish from real science, even by scientists.
Peer review is a popular mechanism scientists used to distinguish actual science from pseudoscience, but it is a flawed mechanism, because a lot of modern science involves a highly detailed and highly technical expertise only a few people in the world possess. As a consequence, many scientists actually lack the knowledgeto qualify as the peers of the (pseudo)scientists whoes work they're expected to judge. Also, the purposeful falsification of data often isn't obvious to detect without repeating the exact same experiments. For both reasons, some pseudoscience manages to succesfully pass for actual science even among scientists.
With pseudoscience passing for science, it should not surprise anyone that the lines between religion and science aren't obvious to everyone. However, it should be noted that any any actual science ( = purged from pseudoscientific claims) is totally distinct from religion due to its total lack of reliance on faith whatsoever.
Western philosophy as we understand it was created when Thales tried to explain the universe without relying on 'The gods did it/willed it to happen' in his answer. However, the 'philosophers' of his time, and for the next long while, were called "fysikós" or physicist. They did not think of themselves as philosophers, but as scientists who performed tests and experiments in much the same way we do, but with different tools, and as their tools were limited many had to be done in their minds. We as a society have taken what is only possible to be done in your mind to be philosophy, and what can be done physically as science. Take the question about free will, there is currently a philosophical debate about whether or not we actually have free will, or if our lives are purely cause and effect relationships that could not possibly turn out differently. There is currently no way to measure this physically, we are certainly not impartial about it, so it stays in the realm of the mind. Once we have a way of measuring this, it will become a science once the physical experiments begin.
The mathematics that we got from the Greeks came from the people we now call Philosophers in their attempt to rationally explain the world around them. Pythagoras who gave us the wonderful Pythagorean Theorem was trying to use numbers and triangle to describe perfection. Perfection is indeed a subjective feeling, so much of philosophy became trying to rationally explain what is subjective, which leads to arguments as people do not all feel the same about what perfection is or it represents.
Philosophy differs from Religion and Spirituality in that it began as mankind's attempt to understand the world without leaning on religion to do it. It does not imply that religion or spirituality are wrong or should be discounted completely. Instead of relying on 'Zeus made the thunder come' philosophy asks 'by what mechanism does thunder come?' If Zeus is indeed present making the thunder come, how does he do it? If he is not there, what makes it happen? Showing that they were trying to separate the world from the requirement of the gods, not trying to say anything about the gods one way or the other.
So in general, Philosophy is asking questions, trying to understand that which we cannot yet measure, attempting to make rational that which is abstract and unknown. Science and Math are questions to which we can apply direct principles to and test how they work physically in the real world. While religion and spirituality would explain the 'why' to science and philosophy's 'how.'
Neither philosophy, nor science, nor religion are "things" which can have objectives (like truth). Only people can have objectives, the philosophers, the scientists and the religious leaders. The subject matters are the deterministic result of all the collected motives of the people doing the work in each field. Other join the field they think most closely resemble to work they want to do, but as other also leave the field it's definition will slightly change because it's definition is entirely constructed from the objectives of the people within it.
Philosophers, scientists and religious leaders might well be motivated by a desire to find some truth, but they will equally be motivated by greed, pride, confirmation bias, laziness, groupthink, social pressures and just about every other bias one can think of. These collectively will affect the emergent "objective" of the filed they go to make up.
So, in order to determine what might be different about those fields, despite the fact that all three claim to be ostensibly about the search for truth, it would be enlightening to ask what motivations other than a search for truth might cause a person to work in one field as opposed to another. Considering that different fields will satisfy different motivations, one could reasonably conclude that their differences were made up entirely of those motivations other than the search for truth (which is common to them all).
For example, science requires a more frequent altering of basic facts using far more apparatus than either philosophy, or religion (which do not change their basic facts very rapidly). So one might argue that people motivated somewhat by laziness would be less likely to pursue truth through science and this in turn will affect the process of philosophy and religion.
Science relies on certain axioms which it does not question, so people motivated to any extent by avoidance of cognitive dissonance might be more attracted to science or religion, where the nature of reality is simply taken for granted, than by philosophy, where it is questioned.
Taking the most pessimistic (realistic) view, none of the disciplines are searching for truth. Science is searching for a controversial theory which will be doubted at first but finally vindicated by experiment, Philosophy is looking for a justification for whatever belief system the philosopher has been cultural reared to believe in regardless, and religion is looking for a set of doctrines sufficiently restrictive to alleviate guilt, but attractive enough to draw a crowd of followers.
Philosophy is a general term that can include all of science. In fact, the two were the same until the 19th century. Before that science was referred to as 'natural philosophy.' This is easy to see if you consider that both are trying to understand how the world is. Mathematics can be derived from logic and can thus be considered a subset of logic, which has also traditionally been a branch of philosophy as well. Therefore, both science and mathematics can be considered subsets or parts of philosophy.
How do science and math differ? In physics, the distinction can be confusing and sometimes people think that physics (and possibly engineering) is applied math. I don't think this is the best way to think about it. While physics (and science, in general) does use math as a tool, science (including physics) is concerned with understanding empirical truths, while math is concerned with numerical relations and the relations that result from their abstraction. Therefore, while scientists and mathematicians can engage in identical tasks, their aim is quite different.
This leaves religion, which is slightly harder to put into relation with philosophy (and by extension math and science). The first problem that arises from trying to differentiate philosophy from religion is that there are too many different things that are called religion. Therefore, a clean (analytical) distinction is not possible. A couple general comments: There is a lot of overlap between philosophy and religion. I think it would be possible for someone to successfully defend a position that orthodox theology was a subset of philosophy. I don't share this view, but think it could be easily defended. This is due to the fact that many religions come with rich philosophical systems. But, I think most religions come with other things that are not usually considered philosophy, like social hierocracies (although, there are schools of thought and journals and organizational structure in philosophy too!). In the end, I think the best way to think about it is to note that many religions contain philosophical systems, but also include things like social hierarchies, which are not usually considered part of philosophy.
In religion there's no "rational" at all but a dogmatic issue about feith.
Regarding science, mathematics and philosophy, I think there's a main difference related to the method. Science uses the scientific method; mathematics uses, let's say, a couple of axioms, a lot of theorems and the strict rule of inference; but in philosophy there's no such unique thing (although many philosophers tried to achieve the "philosophic method").
Both science and mathemathics just can't go beyond their own methods because they are necessary to prove the truth. In philosophy, there's no other way to prove the truth but by providing enough rational arguments in favor of a hypothesis.
For example, science can't answer "Is there a God?" because the method itself requires sensitive experience, and God is anything but sensitive. Philosophy can, at least, make an approach.
However, the question "What is philosophy?" is itself a philosophical problem, in my opinion, far from being resolved.
So that's my grain of sand, I'm sure other users can do it better than just a philosophy enthusiast like me :).
There is very simple and accurate relations on knowledge.
Knowledge or Thought is developed or progressed by these steps.
Dogma > Common Sense > Science > Philosophy > Religion.
Philosophy : ethics
Science : knowledge
Common sense : information
Upper stage may not be explained by lower stage.
Both ends have similar appearance : Dogma and Religion, Common sense and Philosophy.
Then what can be difference ? Overcome science or not.
This theory is not mine. I heard it is suggested by Auguste Comte. However there is not a page in the world who told 1st. Even no one talked this 5 step model.