1. The role of the Common Sense in Metaphysics

2. There are two kinds of people:
the ones who look up at the stars and the ones who look at their feet.
According to the Thales’ anecdote, humanity can be divided in two tribes: philosophers (who try to reach a deeper knowledge of reality) and common run of mankind (who has its common sense beliefs).
Historically, they don’t trust each other.

3. The Rediscovery of Common Sense Philosophy by Stephen Boulter
Every Thing must go by James Ladyman and Don Ross

4. The Rediscovery of Common Sense Philosophy - Stephen Boulter
The Aim of Philosophy
The main goal of Western Philosophy seems to be the providing a general description of the nature of the Universe and the place human beings should take in it. Philosophy deals with the “Big Questions”: therefore philosophical problems regard matters that are out of any specific scientific study area.

5. The Metaphilosophy of Common Sense
The Rediscovery of Common Sense Philosophy - Stephen Boulter
The Metaphilosophy of Common Sense
The author follows the Common Sense Philosophy tradition (Thomas Reid, G.E. Moore…). This philosophical trend has two main features:
Reaction to the Cartesian assumption about reality (that is only thoughts can be self-evident and true while everything else is contingent): Reid claims that philosophy should not discuss on initial data because they belong to sciences’ domain. Philosophical problems are about coordination;
Preference for common sense beliefs (unconscious principles that are obvious for the most of people) than for abstract theories: these philosophers give to the initial data the benefit of doubt while they put the burden of proof upon philosophers’ shoulders. Common sense beliefs have to be accepted until proven otherwise.

6. The debate and the external arbiter
The Rediscovery of Common Sense Philosophy - Stephen Boulter
The debate and the external arbiter
Why should common sense beliefs be taken as default positions? Of course many philosophers disagree with this assumption (Hume, for example, retains that common sense beliefs are only the results of our habits). The fact that we are certain about something does not prove that we are right.
It seems that the debate cannot go further unless an external arbiter adds some other arguments.

7. The Evolutionary Argument and its objections
The Rediscovery of Common Sense Philosophy - Stephen Boulter
The Evolutionary Argument and its objections
Boulter suggests this scientific argument as external arbiter: our common sense beliefs are adaptations that natural selection approves as the best for us and, for this reason, we should not reject them. Common sense beliefs have a very specific sphere of competence (actions environment/practical circumstance): this means that sciences and common sense should rarely clash each other.
It is important to underline that EA does not establish a logical connection between adaptivity and truth, but only a statistical one.

8. The Rediscovery of Common Sense Philosophy - Stephen Boulter
Conclusions
The aim of common sense philosophy is to provide a general picture of the Universe, but according with common sense beliefs;
Common sense beliefs have an ecological/social import while sciences and philosophical theories usually regard the deeper structure of the reality (the competence fields are different);
The difference between science and philosophy is about the verification method: scientists can recognize their errors and they can prove their results.

9. The Rediscovery of Common Sense Philosophy by Stephen Boulter
Every Thing must go by James Ladyman and Don Ross

10. Every thing must go - James Ladyman and Don Ross
The Aim of Philosophy
The authors claim that the only justified metaphysics is the naturalistic one. Quoting Sellars, they suggest that the aim of metaphysics has to be only building bridges between specific areas of scientific knowledge: psychological or cultural familiarity with this explanations is not a value to defend against the objective truth.

11. Naturalistic Metaphysics and Common Sense
Every thing must go - James Ladyman and Don Ross
Naturalistic Metaphysics and Common Sense
What people find intuitive is not innate but a developmental achievement of natural selection: common sense beliefs guide us in our everyday life.
But these natural intuitions do not say anything to us about scientific or metaphysical arguments: this because our common sense image of the world is really limited, both in space and in time and it has got a lot of divergences with contemporary science’s theories. Naturalists are not concerning with preserving these beliefs at all.

12. Naturalism and its principles
Every thing must go - James Ladyman and Don Ross
Naturalism and its principles
According to naturalists, metaphysics should provide a relatively unified picture of the world through a critical research of networks across the sciences. This means that:
The hypothesis should be never beyond our scientific research capacity;
A serious metaphysical proposal should show how two or more scientific (actually accepted) hypothesis could be explained better together: the aim is to find some common argument patterns;
There is a primacy of physics constraint: at least one of these hypothesis has to regard fundamental physics.

13. Naturalism, Reductionism and Scientism
Every thing must go - James Ladyman and Don Ross
Naturalism, Reductionism and Scientism
The primacy of physics’ principle suggests that there are a kind of common fundamental laws at the basis of every science. If every science theory can be reduce to another and more fundamental theory, we can say that all the scientific knowledge can be unified, and this is the basic idea of reductionism. The philosophical stance of the two authors is the result of the fusion between the naturalistic principles and this kind of reductionism: “the only justified metaphysics is an articulation of a unified world-view derived from the details of scientific research.”

14. A «practical» example…
The Privileged Present: defending an A-Theory of time - by Dean Zimmerman

15. Summary of Zimmerman’s Essay
The Privileged Present: defending an A-Theory of time - by Dean Zimmerman
Summary of Zimmerman’s Essay
In this short essay, Zimmerman introduce the McTaggart’s terminology about time theories (a-properties and b-relations) and then he explains the main contemporary A-theories about time:
Presentism (only present events/things exist);
Moving spotlight theory (any event/thing exists as “furniture of the world”);
Growing block theory (only past events/things exist: present is the cutting edge of a growing universe spread in 4 dimensions).

16. Zimmerman’s position and objections
The Privileged Present: defending an A-Theory of time - by Dean Zimmerman
Zimmerman’s position and objections
Zimmerman supports presentism and he retains this philosophical position as the more reasonable one. He answers to the two main objections to presentism: the claim to truthmakers (he suggests a sort of backward-looking properties belonging to present events/things) and the Relativity based objection (he tries to add a special status to one way of slicing the manifold of space-time without undermining the all relativity theory).

17. What does a metaphilosopher of common sense think about this theory?
The Privileged Present: defending an A-Theory of time - by Dean Zimmerman
What does a metaphilosopher of common sense think about this theory?
And what a scientist philosopher?

18. A common sense philosopher would say…
The Rediscovery of Common Sense Philosophy - Stephen Boulter
A common sense philosopher would say…
Presentism should be accepted for its agreement with the common sense belief that past and future things and events are less real than the present ones;
Until the Relativity theory does not provide some strong proves against the presentism, the latter remains the best option;
It seems that about the nature of time, common sense and science are actually fighting each other, despite Boulter’s statement about their different “fields of competence”.

19. What do a metaphilosopher of common sense think about this theory?
The Privileged Present: defending an A-Theory of time - by Dean Zimmerman
What do a metaphilosopher of common sense think about this theory?
And what a scientist philosopher?

20. A scientist philosopher would say…
Every thing must go - James Ladyman and Don Ross
A scientist philosopher would say…
The aim of philosophy should be the connection between different parts of the scientific actual research and not the philosophical interpretation of some scientific theories;
The presentism, as many other philosophical theories, seems to go very beyond our actual capacity of scientific prove and, for this reason, it results useless for a scientist philosopher;
Furthermore, the fact that the presentism agree with some common sense beliefs is absolutely irrelevant to the metaphysics’ enterprise.

21. Thank You for your attention