theory to demonstrate its shortcomings. In order to present the arguments for sense datum theory, it is first necessary to define sense data and its structure and show the principles the position commits to, in doing this the arguments will flow naturally [rivers and blood flows. Arguments don’t. Try to avoid metaphors]. We will explore three arguments in support of sense data and then we will evaluate it [it or them?] to see to what extent it [?] is a credible theory and where it’s weaknesses lie.
Sense data are to be thought of as nonphysical objects of awareness which are logically exclusive to a single subject, the experiencer  . It is also suggested that they do actually possess qualities such as shape, colour and loudness but they do not possess any intrinsic intentionality [what’s that? Explain]. In this way when we undergo a visual experience we assume these sense data are out in the external world through the customs of our own cognitive processing. In fact, sense data possess qualities which do not depict anything outside themselves, they are not representational of the actual world [why not?]. Sense datum theories first begin by accepting the Phenomenal Principle. The Phenomenal Principle claims that if there sensibly appears to a subject to be something which possesses a particular sensible quality then there is something of which the subject is aware which does posses [spelling] that quality. The phenomenal principle when applied to misleading cases of perception is the first argument for sense datum theory.
Let us first take hallucinations. In hallucination there appears to a subject to be something with at least one quality, for instance; a gold car. For the subject, it sensibly appears to be the case that something has the quality of being gold and according to the phenomenal principle if this is the case, then there really is something with the quality of being gold. As a hallucination, however, the thing that possesses this goldness cannot reside in the real world  . Even though in the case of illusory experience there is an experienced object, it is not dissimilar in its support for sense data [not clear. Rewrite]; the subject experiences something that possesses a quality when it in fact does not have that quality  . In the car example, if the car which is in fact red looks gold to the subject then, according to the phenomenal principle, there is something of which the subject is aware which possesses the quality of goldness, even if it is not the car. If were [grammar] to formalise the arguments from misleading experiences it [plural or singular? grammar] would run as follows:
P1: If there appears to a subject to be something which possesses a particular quality then there is something of which the subject is aware which does possess that quality.
P2: In hallucination there appears to a subject to be something which possesses a particular quality when there is no object present in the external world. In illusion there appears to a subject to be something which possesses a particular quality when there is no object that possesses that particular quality.
C: In both hallucination and illusion, the thing that the subject is directly aware of is not an object in the external world.
If the objects are not in the external world and clearly there is nothing which possesses qualities such as goldness in the subjects [grammar, genitive] brain, the subject (for the sense data theorist at least) is experiencing is the non physical sense data [I don’t understand. Rewrite].
There is a second principle that the sense data theorist endorses and uses to argue for sense datum’s existence and that is the common factor principle; Phenomenologically [why do you capitalize the term here?] indiscriminable perceptions, hallucinations,
and illusions have an underlying mental state in common (the state of being aware of sense data [why is that? How do you get that they have something on common to the view that this commonality is awareness of sense data? Explain]. The common factor principle takes the conclusion of the phenomenological principle and builds one further step; that what we are aware of in veridical perception is also sense data. It utilises the notion of indiscriminability and claims that in both Hallucination [spelling] and illusion we have experiences which are indiscriminable from those we undergo in perceptions and thus if the first two are thought to be products of sense data, then there is no tangible reason to say that perception isn’t. This portion of the argument is extended further by A.D Smith; Smith contends that our perceptions and illusory experiences will interchange quite regularly  (when I view a colour in deceiving light and then in true light). The point being made is that on this grounding it would be less than satisfactory to suggest that we are experiencing one type of awareness in the illusory case and another, distinct type in the perceptual case [why?].
The third and final argument we will explore here is the time lag argument  and it works in a different manner to the aforementioned claims. It looks to use align [grammar] the phenomenal principle and the premise that in time lag cases, there appears to a subject to be something which possesses a particular quality when the object in the external world either no longer exists or has changed its qualities. The strength of this premise can be derived from science in that we know that where distant objects are concerned, light from those objects takes a finite time to reach us. For instance, light from a star ten million light years away has taken, by definition, ten million years to reach us, and by this time (the time at which we experience it) it has either changed or even ceased to exist [what’s the referent of ‘it’? Write clearly.]. The argument is clear then; if we are not experiencing the object itself, we must be experiencing sense data.
To this point we have presented the three most prevalent arguments for sense data and now, as there are grounds to do so, we shall critically engage the theory.
The first concern comes from both epistemological concerns and from our intuitional concerns [is that a ‘first concern’ or several ‘concerns’?]. Sense data theory appears to open the chasm of external world scepticism. If we can only be aware of purely non physical sense data then on what grounds can we believe anything physical really exists? Jackson retorts by claiming that although we cannot validly deduce the existence of physical things from our sense data, we might infer the existence of physical things non demonstratively [not clear. Explain. Flesh out the point.]  . To take a Humean view, however, all non demonstrative reasoning employs inductive reasoning [why?], generalisations from our past experiences. In this way we still cannot infer the existence of physical objects because the entirety of our past experiences are comprised of sense data; it is only of sense data that we may then generalise.
A second and more substantial objection is the argument from indeterminacy. As we have seen, sense data are suppose [spelling] to have those properties that we experience in perception. If I experience goldness then I have a gold sense datum and, in the same fashion, if I do not experience goldness, I do not have a gold sense datum. The issue, then, is that in some cases it is indeterminate which properties an object appears to have, for instance, an object might appear to have stripes but one could not determine exactly how many stripes one saw. The same is of objects that are far away, we have an inability to say exactly how far away they are, and in the case of words, we have an inability to read far away words. If the apparent properties of objects of perception are sometimes indeterminate, then the sense data would also have to be indeterminate, that is, they would have to actually lack definite characteristics [andâ€¦why is that problematic?]. Ayer’s response to this criticism is to suggest that in cases where it is indeterminate, say, how many stripes something has, the sense datum does not have any definite number of stripes. It is with some confidence that I suggest this could not be so and that Ayer should revise this position, an object could not have stripes but no definite number of stripes, it could not bear goldness but no definite shade of gold; this is absurd.[right. Say this earlier or connect things better.] If sense data theorists are to continue to analyse experiences in such a way that there is thought to always be an actual object that really does bear the properties that the subject experiences, then this issue of indeterminacy will continue to plague them.
The theory of sense data is an interesting and appealing theory, it is well supported [by what?] but only insofar as it has been built around observations, rather than these observations overtly pointing to the existence of sense data.
Just two of it’s [spelling] more interesting shortcomings have been explored in this essay but this is not to say it has no others. It falls prey to physicalism [how?], to other epistemic objections and to the intuitional question; where do sense data reside? Unfortunately we cannot enlarge upon these objections here. What can be said is that whilst the danger of scepticism seems enough to want to reject sense data, it is the vague and indeterminate nature of our experiences that poses the more fatal objection, one that has yet to be satisfactorily dealt with by the sense data theorist.
[General comments: I think you have a good grasp of the argument for sense data, and you mention two major